Chapter 1 – Environmental Health

Que. 1. What are the constituents of cultural environment?

Ans. 1. Important constituents of Cultural Environment are Knowledge, attitude, beliefs, practices, culture, customs, traditions and habits.

Que. 2. What are the merits of the ground water?

Ans. 2. The merits of ground water are as follows – 

1. It is free from pathogenic micro-organisms and harmful chemical substances
2. It does not require purification especially if drained below the first impervious layer of the ground
3. Available even during summer season especially if deep well water.

Que. 3. What are the demerits of ground water?

Ans. 3. The demerits of ground water include – 

1. Mineral content is high making it hard water
2. Requires certain arrangements for lifting the water above ground level e.g. pump.

Que. 4. What do you mean by cone of filtration?

Ans. 4. The area from where pollutants and pathogens are drained to a particular well, especially shallow one, is called cone of filtration. It is represented by an inverted cone, apex being bottom of well and base being surface of earth.

Que. 5. Enumerate the components of environment?

Ans. 5. Four components – physical environment, biological environment, social environment and cultural environment.

Que. 6. What do you mean by artesian well?

Ans. 6. It is a type of deep well, in which water table is at a higher level than the surface of the earth, because of the slope of the impervious layer. Therefore, water is held under pressure between the two impervious layers. When a bore taps the water, water comes out as fountain. These wells are not common in India.

Que. 7. What is the effect of hardness of water on cardio-vascular diseases?

Ans. 7. Hardness of water have a beneficial effect on cardio-vascular diseases. Soft water leads to cardio-vascular diseases.

Que. 8. What do you mean by water-washed diseases?

Ans. 8. Diseases transmitted by inadequate use of water are called Water-washed diseases e.g. Trachoma, conjunctivitis, shigellosis & scabies. 

Que. 9. When was slow sand filter or biological filter used for the first time?

Ans. 9. In England in 1804.

Que. 10. Which component of slow sand filter does measure loss of hydraulic head?

Ans. 10. Venturimeter.

Que. 11. What do you mean by loss of hydraulic head?

Ans. 11. It is the frictional resistance offered by the vital layer and the sand bed of the filter.

Que. 12. What do you mean by term filter run?

Ans. 12. It is the period during which the filter is run continuously without scrapping of sand bed is called as filter-run. This period is 3 weeks to 3 months in slow sand filter, depending upon the quality of water.

Que. 13. What are the advantages of slow sand filter?

Ans. 13. The advantages of slow sand filter are – 

1. Simple to construct & easy to operate
2. Less costly than rapid sand filter
3. Physical, chemical, biological quality of filtered water is very high (99.9% bacteria are removed).

Que. 14. What are the disadvantages of slow sand filter?

Ans. 14. The disadvantages of slow sand filter are as follows – 

1. Large area required to construct.
2. Slow rate of filtration
3. Not very effective in removing colloidal matter and colour
4. Long period, around 18 hours, required for filtration of water.

Que. 15. What are the disadvantages of rapid sand filter?

Ans. 15. The disadvantages og rapid sand filter are as follows – 

1. The water requires preliminary treatment.
2. Requires the services of skilled persons
3. Formation of mud balls lead to cracking of filters.

Que. 16. Who did initiate the use of chlorine compounds for disinfecting water?

Ans. 16. G A Johnson (1908).

Que. 17. Roughly how much bleaching powder is required to disinfect 1000 litres of water?

Ans. 17. Around 2.5 gram.

Que. 18. Which equipment is used to determine the amount of bleaching powder required to disinfect the water?

Ans. 18. Horrock’s Apparatus.

Que. 19. What are the roles of bleaching powder in environment health?

Ans. 19. Following are the roles of bleaching powder – 

1. Disinfection of water
2. Disinfection of saliva, sputum & excreta of the infected patient (50 gm of 8% strength chlorine of bleaching powder is required to for 1 litre of faeces & urine).

Que. 20. What do you mean by stabilized bleach?

Ans. 20. Addition of excess of lime to the bleaching powder in the ratio of 4:1, stabilizes the chlorine content of the bleaching powder. This stable form is called Stabilized Bleach which retains its potency up to 1 year.

Que. 21. Which is the test used to measure the free chlorine in the water?

Ans. 21. Orthotolidine test. The apparatus used for the purpose is called CHLOROSCOPE.

Que. 22. What do you mean by hard water?

Ans. 22. Hardness does not readily form lather with soap.

Que. 23. What are the causes of hardness of water?

Ans. 23. Temporary hardness is due to the presence of carbonates & bicarbonates of calcium & magnesium while permanent hardness is due to the presence of sulphates, chlorides and nitrates of calcium and magnesium.

Que. 24. How will you grade the hardness of water?

Ans. 24. The hardness of water can be graded as – 

1. Less than 1 meq/L (i.e. <50 ppm) – SOFT WATER
2. 1-3 meq/L (50-150 ppm) – MODERATELY HARD WATER
3. 3-6 meq/L (150-300 ppm) – HARD WATER
4. More than 6 meq/L (>300 ppm) – VERY HARD WATER

Que. 25. What should be the level of hardness of drinking water?

Ans. 25. It should be moderately hard.

Que. 26. What are the disadvantages of hard water?

Ans. 26. The disadvantages of hard water are as follows – 

1. It causes wastage of soap.
2. Affects cooking adversely
3. Causes irritation of skin & GIT
4. Reduces the life of clothes washed with soap in hard water
5. Forms scales in the boilers.

Que. 27. What is the advantage of hard water?

Ans. 27. It is cardio-protective. Population consuming hard water has low cardiovascular mortality rates.

Que. 28. How will you remove temporary hardness?

Ans. 28. By boiling of water, addition of lime, addition of sodium carbonate & permutit process.

Que. 29. How will you remove permanent hardness of water?

Ans. 29. By two processes – by adding sodium carbonate & by permutit process.

Que. 30. What sort of examinations are included in the lab examination of water?

Ans. 30. Various types of examinations included are – 

1. Physical Examination
2. Chemical Examination
3. Biological Examination
4. Bacteriological examination
5. Radiological Examination
6. Virological Examination

Que. 31. How is turbidity of water measured?

Ans. 31. By Jackson Candle Turbidimeter.

Que. 32. How is colour of water determined?

Ans. 32. Instrument used to determine the colour of water is called COLORIMETER.

Que. 33. Which are the methods recommended for estimation of fluorides in water?

Ans. 33. Methods recommended are – 

1. Colorimetric method, using zirconium-alizarin reagent
2. Electrochemical method using orion electrode
3. SPANDS –colorimetric method

Que. 34. How will you interpret the results of bacteriological examination of disinfected water?

Ans. 34. May interpret in following way – 

1. No coliforms in 100 cc of water – EXCELLENT WATER
2. 1-3 coliforms in 100 cc of water – SATISFACTORY WATER
3. 4-10 coliforms in 100 cc of water – SUSPICIOUS WATER
4. > 10 coliforms in 100 cc of water – UNSATISFACTORY WATER

Que. 35. Enumerate the name of tests used to detect faecal streptococci & Cl. Perfringens?

Ans. 35. For detection of faecal streptococci –

1. By using glucose-azide broth
2. By using BAGG medium
3. Membrane filtration technique

For detection of Cl. Perfringens – 

1. By using DRC medium.

Que. 36. What is the upper limit fixed by WHO for viruses per litre of water?

Ans. 36. 1 PFU (Plaque forming unit).

Que. 37. What do you mean by comfort zone?

Ans. 37. It is the range of corrected effective temperature in which the individual or worker in a factory, feels comfortable. The criteria are – 

1. Corrected effective temperature – 25 to 27 degree C (77-80 degree F)
2. Relative humidity – 30-65%
3. Dry Kata – 6 & above
4. Wet Kata – 20 & above
5. Predicted 4 hour sweat rate (P4SR) – 1-3 litres

P4SR is applicable only in that situation where sweating occurs.

Que. 38. Which are the major sources of air pollution?

Ans. 38. Major sources of air pollution are – 

1. Domestic sources
2. Industrial sources
3. Vehicular sources
4. Agricultural sources
5. Miscellaneous – Smoking, forest-fire, burning of refuse, dust storm etc.

Que. 39. What are the hazards of air pollution?

Ans. 39. The hazards of air pollution are as follows – 

1. ACUTE EFFECTS 

1. Irritation of conjunctiva, nose, throat & respiratory mucous membrane
2. Conjunctivitis
3. Allergic rhinitis
4. Acute pharyngitis
5. Acute bronchitis
6. Episodes of bronchial asthma

1. CHRONIC EFFECTS

1. Chronic bronchitis
2. Bronchiectasis
3. COPD
4. Bronchial Asthma
5. Lung Carcinoma

Que. 40. What do you mean by global warming?

Ans. 40. Global warming is the phenomenon of gradual increase in the average temperature of the earth. It is caused by release of greenhouse gases e.g. Carbon dioxide, methane, CFCs etc.

Que. 41. What are the causes of global warming?

Ans. 41. The causes of global warming are as follows – 

1. Deforestation
2. Use of vehicles
3. Chlorofluorocarbons (CFCs) due to excessive use of ACs and refrigerators
4. Industrial development
5. Agriculture
6. Overpopulation
7. Forest blazes
8. Volcano eruptions etc.

Que. 42. What are the effects of global warming?

Ans. 42. The effects of global warming are – 

1. Increase in dryness of the climate
2. Reduction in world food production
3. Melting of polar icecaps
4. Increase in sea level resulting in floods
5. Smog formation
6. Increased incidence of skin cancer and cataract
7. Spread of tropical diseases to temperate regions

Que. 43. What is the greenhouse effect?

Ans. 43. The greenhouse effect is the process through which heat is trapped near earth’s surface by substances known as greenhouse gases. The process is called greenhouse effect because the exchange of incoming and outgoing radiation that warms the planet works in a similar way to a greenhouse. The greenhouse gases include carbon dioxide, methane, nitrous oxide, hydro-fluorocarbons, perfluorocarbons, sulphur hexachloride & nitrogen trifluoride.

Que. 44. What are the causes of greenhouse effect?

Ans. 44. The causes of greenhouse effect are – 

1. Burning of fossil fuels e.g. coal, oil, gas & peat in the industries
2. Carbon emissions from car exhausts
3. Methane & nitrous oxide emissions from agriculture
4. Extensive use of refrigerators and ACs
5. Deforestation and
6. Rapid urbanization

Que. 45. What are the effects of depletion of ozone layer around the earth?

Ans. 45. The effects of depletion of ozone layer are – 

1. Inhibition of photosynthesis
2. Disruption of marine food chain
3. Impairment of human immune mechanism, pre-disposing for infections
4. Ocular damage like cataract
5. Skin Cancers
6. Damage to building like old monuments etc.

Que. 46. Name the indicators of air pollution used for its monitoring?

Ans. 46. Indicators used for air pollution monitoring are – 

1. Sulphur dioxide index
2. Smoke (soiling) index
3. Suspended particles
4. Coefficient of haze
5. Other parameters e.g. lead, CO etc.

Que. 47. How many types of artificial or mechanical ventilation do you know?

Ans. 47. 4 types – 

1. Vacuum System
2. Plenum system
3. Balanced system
4. Air-conditioning

Que. 48. When will you call lighting adequate in a room?

Ans. 48. When in the darkest corner of the room, a person is able to read at a distance of 25 cm.

Que. 49. What do you mean by noise pollution?

Ans. 49. It signifies the cacophony of sounds that are being produced in the modern life, leading to health hazards.

Que. 50. Which instrument is used to measure the intensity of sound in decibels (dB)?

Ans. 50. Sound level meter.

Que. 51. Which instrument does indicate whether the intensity of sound is high pitched or low pitched?

Ans. 51. Octave band frequency analyser.

Que. 52. What does audiometer measure?

Ans. 52. It measures the hearing ability. Zero line at the top of audiogram represents normal hearing.

Que. 53. Name the drugs that increases the susceptibility to radiations.

Ans. 53. Metronidazole & brom-uridane.

Que. 54. Enumerate the important factors on which radiation hazards do depend.

Ans. 54. Important factors are – 

1. Intensity of the radiation
2. Duration of exposure
3. Individual susceptibility

Que. 55. Which level of exposure of radiation for a short period does result in acute radiation syndrome?

Ans. 55. 1-9 Gy.

Que. 56. What do you mean by terrestrial radiations?

Ans. 56. These are the radiations that originate from radioactive substances such as ores of radium, uranium & thorium present in the earth’s crust or rocks or buildings.

Que. 57. What are the types of radiations?

Ans. 57. Two types of radiations – 

1. Non-ionizing radiations 

• U-V rays
• Visible light
• Infrared rays
• Microwaves
• Radiofrequency waves
• Laser radiations

1. Ionizing radiations 

1. Electromagnetic radiations (Photon radiations) e.g. X-ray, Gamma rays
2. Corpuscular (Particulate) radiations e.g. Alpha particles, Beta particles, Neutrons.

Que. 58. What are the health hazards of improper solid waste/refuse disposal?

Ans. 58. Health hazards of improper solid waste disposal are as follows – 

1. Pollution of water & soil.
2. Contamination of food & drinks through dust & flies
3. Decomposed waste favours propagation of houseflies
4. Attracts rodents & vermin.
5. Nuisance by sight & smell.

Que. 59. Which is the most insanitary method of solid waste disposal?

Ans. 59. Dumping.

Que. 60. Which method of solid waste disposal is used to dispose refuse along with the night soil or sewage?

Ans. 60. Composting.

Que. 61. Which is the most sanitary method of solid waste disposal?

Ans. 61. Incineration. Feasible where suitable land for sanitary landfill is not available.

Que. 62. What are the important features of an incinerator?

Ans. 62. Important features of an incinerator are – 

1. A furnace or combustion chamber lined with fire bricks where the fire is built with firewood or electricity.
2. A platform for tipping the refuse.
3. Stokers to bring the refuse together for burning completely.
4. A baffle plate to drive of all the fumes.

Que. 63. What is the sullage?

Ans. 63. Sullage is the waste water coming out from kitchen & bathroom.

Que. 64. How will you dispose of sullage?

Ans. 64. Sullage can be disposed of by – 

1. Pervious pit such as soakage pit
2. Impervious pits or non-soakage pits such as septic tank
3. Surface irrigation such as kitchen garden
4. Underground drainage or sewerage system

Que. 65. What are the objectives of sewage treatment?

Ans. 65. The objectives of sewage treatment are as follows – 

1. Protection of water source from contamination
2. Prevention of nuisance by sight & smell
3. Protection of soil from contamination
4. Protection of fish & aquatic lives
5. Protection of human foods
6. Protection of hazards to live-stocks.

Que. 66. What are the health hazards of improper excreta disposal?

Ans. 66. It causes pollution of the physical environment such as food, water & soil and results in many diseases e.g. Typhoid, Paratyphoid, diarrhoeal diseases, dysenteries, Amoebiasis, ascariasis, viral hepatitis, polio myelitis, ankylostomiasis etc. all resulting in increased morbidity & mortality in a community.

Que. 67. Who did introduce bore-hole latrine for the first time?

Ans. 67. ROCKFELLER FOUNDATION during 1930’s to combat hookworm infestation.

Que. 68. What are the disadvantages of bore-hole latrine?

Ans. 68. The disadvantages of a bore-hole latrine are – 

1. Fills up rapidly because of small capacity
2. The special equipment Auger may not be easily available
3. Difficult to construct if soil is loose.

Que. 69. When was dug well or pit latrine first introduced?

Ans. 69. In 1949 in Singur, West Bengal.

Que. 70. What do you mean by water seal type of latrines?

Ans. 70. These are the latrines having a bend pipe (trap) below the squatting plate, always holding some amount of water providing water seal.

Que. 71. What is the water seal?

Ans. 71. Water seal is the distance between the level of water in the trap and the lowest point on the concave upper part of the trap.

Que. 72. What are the advantages of water seal?

Ans. 72. It prevents the access of flies and also prevents foul smell and nuisance.

Que. 73. Which is the most acceptable type of water seal latrine?

Ans. 73. RCA type.

Que. 74. What do you mean by septic tank latrine?

Ans. 74. It is an ideal sanitary water seal latrine which can meet the requirements of families in towns and cities having piped water supply but no sewerage system. It is not recommended for large communities.

Que. 75. What are the requirements of a septic tank installation?

Ans. 75. Following are the requirements of a septic tank installation – 

1. There must be sufficient water supply to flush out the excreta to the tank
2. Detergents and disinfectants should not be used in the tank
3. There must be sufficient gap between the fluid level and the cover to accommodate the scum and the gases.
4. There should be a ventilator pipe to let off the foul gases.
5. Desludging should be done periodically.

Que. 76. Which is the recommended sanitary temporary latrines for fair, mela & camp?

Ans. 76. Shallow & deep trench latrines.

Que. 77. Which is the recommended sanitary latrine for isolated houses, boats & aircrafts?

Ans. 77. Chemical closet.

Que. 78. Name the chemicals used in chemical closet?

Ans. 78. A solution of caustic soda & phenol and covered with a layer of crude oil.

Que. 79. What are the merits of biogas plant?

Ans. 79. The merits of biogas plant are as follows – 

1. Both human & animal excreta disposed of simultaneously
2. Good source of energy at a low cost
3. Refuse also can be disposed of
4. Provides an organic manure
5. Eco-friendly
6. Involves active community participation
7. May be installed at the family or community level

Que. 80. What are the elements of sewerage system?

Ans. 80. The elements of sewerage system are as follows – 

1. House drainage 

• Water closet
• Soil pipes
• House drain

1. Public sewer
2. Sewer appurtenances

• Inspection chamber
• Intercepting trap

Que. 81. What do you mean by sewage farming?

Ans. 81. Disposal of sewage in porous acres of land. Generally an acre of land would be required for sewage disposal of 300 persons.

Chapter 2 – DEMOGRAPHY & FAMILY PLANNING

Que. 82. What do you mean by High stationary stage of demographic cycle?

Ans. 82. It is the first stage and is characterized by high birth & death rates which cancel each other and population remains stationary e.g. India prior to 1920.

Que. 83. What do you mean by 2nd stage, early expanding stage of demographic cycle?

Ans. 83. Death rate starts declining but birth rate remains unchanged resulting in increase in population e.g. many countries in Africa & South Asia.

Que. 84. What do you mean by 3rd stage, late expanding stage of demographic cycle?

Ans. 84. Death rate declines further& birth rate starts falling resulting in increase in population e.g. India, China, and Singapore etc.

Que. 85. What do you mean by 4th stage, low stationary stage of demographic cycle?

Ans. 85. It is characterized by a low birth and death rate resulting in stationary population e.g. Austria.

Que. 86. What do you mean by 5th stage, declining stage of demographic cycle?

Ans. 86. It is characterized by low birth rate in comparison to death rate resulting in declining population e.g. Germany & Hungary.

Que. 87. Enumerate the demographic processes.

Ans. 87. Fertility, Mortality, Marriage, Migration & Social Mobility.

Que. 88. At which rate world’s population is growing?

Ans. 88. 1.1% (UN 2022).

Que. 89. What are the key factors responsible for decline in fertility globally?

Ans. 89. The key factors responsible are – 

1. Changes in government’s attitude
2. Spread of education
3. Increased availability of contraception
4. Extension of services offered through Family Planning programs
5. Changes in marriage pattern.

Que. 90. Globally what are the important reasons for marked reduction in infant and child mortality?

Ans. 90. Important reasons are – 

1. Political will
2. Improvement in maternal & child health services
3. Successful Expanded program on immunization
4. Successful implementation of diarrheal diseases & ARI control programs
5. Control of other infectious services
6. Improvement in feeding practices of infants and children.

Que. 91. What do you mean by growth rate?

Ans. 91. When the Crude death rate (CDR) is subtracted from the Crude birth rate (CBR), the net residual is the current growth rate (exclusive of migration).

Que. 92. What do you mean by demographic dividend?

Ans. 92. When population of working ages (25-64 years) is growing faster than in old age groups, it provides an opportunity for accelerated economic growth. This phenomenon is called demographic dividend.

Que. 93. What does vital statistics measure?

Ans. 93. Birth rate, Death rate, Natural Growth Rate, Life expectancy at birth, mortality & fertility rates.

Que. 94. What is the role of demographic indicators?

Ans. 94. They help in identifying areas that need policy & programmed interventions, setting near & far term goals and deciding priorities, besides understanding them in an integrated structure.

Que. 95. What do you mean by total dependency ratio?

Ans. 95. The ratio of combined age groups 0-14 years plus 65 years and above the 15-65 years age group is referred to as total dependency ratio.

Que. 96. What do you mean by demographic bonus?

Ans. 96. The term indicates the period when the dependency ratio in a population declines because of decline in fertility, until it starts to rise again because of increasing longevity.

Que. 97. What does a low sex ratio indicate?

Ans. 97. A low sex ratio indicates – 

• Strong male child preference

• Gender inequities

• Neglect of the girl child

• High mortality at younger age

• Female infanticide

• Female foeticide

• High maternal mortality

• Male bias in enumeration of population

Que. 98. What do you mean by the term demographic burden?

Ans. 98. Demographic burden reflects the increase in total dependency ratio during any period of time, mostly caused by increased old age dependency ratio. This is the consequence of demographic transition that every country has to face sooner or later.

Que. 99. What do you mean by family size?

Ans. 99. It means the total number of the children a woman has borne at a given point in time. Total fertility rate (TFR) denotes the approximate magnitude of completed family size.

Que. 100. Which are the factors that affect the family size?

Ans. 100. The factors that affect the family size are as follows – 

1. Duration of marriage
2. Early marriage
3. Education of the couple
4. Number of live births and living children
5. Preference of male child
6. Desired family size
7. Limited use of contraceptives
8. Universality of marriage.

Que. 101. What should be ideal spacing between children?

Ans. 101. Three years (Birth to birth).

Que. 102. What do you mean by family planning?

Ans. 102. Family planning refers to practices that help individuals or couples to attain certain objectives – 

1. To avoid unwanted births
2. To bring about wanted births
3. To regulate the intervals between pregnancies
4. To control the time at which birth occurs in relation to ages of parents
5. To determine the number of children in the family.

Que. 103. What are the advantages of family planning in relation to maternal health?

Ans. 103. The advantages of family planning in relation to maternal health are – 

1. Reduces maternal mortality & morbidity
2. Improves nutritional status (Haemoglobin etc.)
3. Prevents complications of pregnancy & abortion.

Que. 104. What do you mean by eligible couples?

Ans. 104. Eligible couple is a couple wherein the wife is in reproductive age (15-40 years), who is eligible and in need of family planning services.

Que. 105. Where is an eligible couple recorded by the health worker?

Ans. 105. Eligible couple register & this register is updated regularly.

Que. 106. What is the magnitude of eligible couples in India?

Ans. 106. 150-180 eligible couples per 1 lakh population.

Que. 107. What do you mean by Couple Protection Rate?

Ans. 107. The percentage of eligible couples effectively protected against child birth by one or the other method of contraception.

Que. 108. What do you mean by target couples?

Ans. 108. Target couples are those couples who have had 2 or 3 living children thus constituting priority group for uptake of terminal or permanent methods.

Que. 109. What do you mean by unmet need for family planning?

Ans. 109. Currently married women who are not using any contraceptive methods but want to use them to avoid further pregnancies are defined as having an unmet need for family planning.

Que. 110. What is the current unmet need of family planning in India?

Ans. 110. Total unmet need – 9.4.

                  Unmet need for spacing – 4.0 (NFHS-5, 2019-21)

Que. 111. What is the current couple protection rate in India?

Ans. 111. Any methods – 66.7%; Modern methods – 56.5% (NFHS-5, 2019-21)

Que. 112. What is the current total fertility rate (TFR) of India?

Ans. 112. 2.0 (NFHS – 5, 2019-21)

Que. 113. What do you mean by an ideal contraceptive method?

Ans. 113. It is the one, who is safe, effective, acceptable, inexpensive, reliable, reversible, simple, and long lasting, independent of coitus and requires less medical supervision. 

Que. 114. Whether it is necessary to remove air from the teat end of condom before use?

Ans. 114. Yes, otherwise condom may tear due to force of ejaculation.

Que. 115. What are the demerits of condom?

Ans. 115. The demerits of condom are as follows – 

1. If not properly used, it may slip off or tear during sex act
2. It interferes with sex sensation
3. Rarely allergic reaction can occur to latex
4. Becomes weak if stored for long time
5. It cannot be used more than once.

Que. 116. What are the indications for removal of IUD?

Ans. 116. The indications are as follows – 

1. Major bleeding or severe pain
2. Occurrence of pregnancy
3. Development of pelvic inflammatory disease (PID)
4. Partial expulsion of IUD
5. Perforation of uterus
6. When lifespan of IUD has reached or women reach menopause.

Que. 117. Who is an ideal IUD candidate?

Ans. 117. She is a woman in reproductive age group, has given birth to a child, not having any PID and not having multiple sex partners.

Que. 118. What is the ideal time of IUD insertion?

Ans. 118. Can be inserted into the uterus at any time during menstrual period. However ideal time is after 5th day and before 10th day of menstrual cycle. This is called intermenstrual insertion.

Que. 119. What do you mean by post placental insertion of IUD?

Ans. 119. This means insertion of IUD immediately (within 10 minutes) following delivery of the placenta, on the same delivery table.

Que. 120. What do you mean by immediate post-partum insertion of IUD?

Ans. 120. This means insertion of IUD within 48 hours of delivery of baby. Done by Kelley’s forceps.

Que. 121. What do you mean by post-coital insertion of IUD?

Ans. 121. This means insertion of IUD within 3 to 5 days of unprotected intercourse, to provide post-coital contraception. This is also one of the methods of emergency contraception.

Que. 122. What do you mean by post abortion insertion of IUD?

Ans. 122. In this, IUD is inserted as early as possible after abortion especially when bleeding stops.

Que. 123. What is the most common & serious side effect of IUD?

Ans. 123. Vaginal bleeding.

Que. 124. What do you mean by Yuzpe method?

Ans. 124. This method consists of consuming either 8 low dose COC pills (MALA D)(4 as soon as possible followed by another 4 after 12 hours) or 4 standard dose combined pills (MALA N) (2 pills followed by another 2 pills after 12 hours).

Que. 125. What are the demerits of Yuzpe method?

Ans. 125. Once implantation of ovum has occurred, it is not effective. Failure rate is 0.2 to 2%.

Que. 126. When DMPA can be given in a lactating woman?

Ans. 126. 6 weeks after childbirth.

Que. 127. When DMPA can be given after abortion?

Ans. 127. Within 7 days.

Que. 128. When does the fertility return after stoppage of DMPA?

Ans. 129. 6-7 months.

Que. 129. What is the failure rate of DMPA?

Ans. 129. About 0.3 pregnancies per 100 women years.

Que. 130. What are the contraindications of DMPA?

Ans. 130. The contraindications of DMPA are as follows – 

1. Pregnancy
2. Early postpartum period (within 6 weeks of delivery)
3. Suspected malignancy
4. PID
5. Bleeding disorders

Que. 131. How will you insert Norplant?

Ans. 131. He capsules are inserted subcutaneously, by a small incision under local anaesthesia in the upper arm of the women. After all capsules are inserted, the incision is closed with an adhesive bandage. Stitches are not necessary.

Que. 132. What is the effectiveness of Norplant?

Ans. 132. Effective for 5 years.

Que. 133. What is the failure rate of Norplant?

Ans. 133. The 1-6 pregnancies per 100 women years.

Que. 134. Name important post-conceptional methods.

Ans. 134. Different post-conceptional methods are as follows – 

1. Menstrual Regulation
2. Menstrual induction
3. Induction of abortion.

Que. 135. What do you mean by Menstrual Regulation (MR)?

Ans. 135. It means regularizing the menstrual cycle in a woman, who had her cycles regularly previously but now missed and delayed by 1-2 weeks, before any pregnancy test can confirm whether she is pregnant or not. The Menstrual Regulation (MR) consists of evacuation of the contents of the uterus.

Que. 136. Which are the instruments used for menstrual regulation?

Ans. 136. Karmann cannula & Menstrual Regulation (MR) syringe.

Que. 137. How do menstrual regulation differ from early abortion?

Ans. 137. Menstrual Regulation differs from early abortion by the following – 

1. There is no certainty that she is pregnant
2. There is no legal restrictions
3. There is increased safety of the early procedure.

Que. 138. How is menstrual induction carried out?

Ans. 138. By intrauterine application of 2.5 to 5 micro gm solution of prostaglandin F2 under sedation. 

Que. 139. What is the most important demerit of menstrual regulation?

Ans. 139. Uterine perforation.

Que. 140. What is the nature’s method of birth control?

Ans. 140. Spontaneous abortion.

Que. 141. What are the complications of abortion?

Ans. 141. Haemorrhage, shock, perforation of uterus, thrombo-embolism & the late complications are infertility, ectopic pregnancy, maternal mortality and morbidity.

Que. 142. What do you mean by medical methods of abortion (MMA)?

Ans. 142. It is a non-surgical intervention to terminate unintended, early pregnancies, based on proven regimen combining two drugs – Mifepristone & Misoprostol.

Que. 143. What is the contribution of unsafe abortion in the maternal mortality ratio (MMR)?

Ans. 143. Responsible for 8% of maternal deaths.

Que. 144. What are the social factors contributing to unsafe abortion?

Ans. 144. The social factors contributing to unsafe abortion are as follows – 

1. Lack of information that abortion is legal & is available in the health facilities.
2. Belief of killing a life is woven around abortion & there is social stigma related to abortions.
3. Gender discrimination and the low status of women in the society
4. The safety of a woman is further jeopardised by the involvement of multiple decision makers around her
5. Ignorance about contraception and the lack of male participation in preventing unintended pregnancy
6. Women do not go to male service providers.

Que. 145. What are the policy factors impacting access to safe abortion services?

Ans. 145. The policy factors are – 

1. Scarcity of qualified providers for safe abortion services
2. Inadequate equipment & supplies essential for providing services
3. Insisting on acceptance of a particular contraceptive method during abortion care
4. Weak referral linkages.

Que. 146. What are the economic factors contributing to unsafe abortion?

Ans. 146. The economic factors contributing to unsafe abortion are as follows – 

1. Loss of wages affect the individual’s decision to seek health care.
2. Private providers charge high fees for abortion services.

Que. 147. What are the broad categories of policies for safe abortion care?

Ans. 147. The broad categories of policies for safe abortion care are as follows – 

1. Integrated strategic approach under RMNCH+A
2. Establishing Comprehensive Abortion Care (CAC) service delivery
3. Generating awareness.

Que. 148. Under RMNCH+A, what is the strategic approach formulated for safe abortion services?

Ans. 148. To integrate the early detection of pregnancy, safe abortion care services & contraceptive counselling / services to address unintended pregnancies & abortion.

Que. 149. What is the approach adopted in CAC service delivery?

Ans. 149. Woman – Centred Approach.

Que. 150. When was Medical Termination of Pregnancy (MTP) Act, enacted?

Ans. 150. 1971.

Que. 151. Up to which period of gestation, generally medical methods of abortion (MMA) can be prescribed?

Ans. 151. 7 weeks of gestation.

Que. 152. When will you call an abortion legal?

Ans. 152. An abortion is called legal when it fulfils the following conditions – 

1. If performed by registered medical practitioner, who is allowed to terminate the pregnancy, as defined by the MTP Act.
2. If it is performed at a place that has been approved to terminate pregnancy under the MTP Act. For medical methods of abortion (MMA), up to 7 weeks of gestation, drugs can be prescribed in OPD with an established referral linkage to an MTP approved site.
3. If the other requirements of the act such as gestation period, consent, opinion of RMP, RECORD keeping and reporting are fulfilled.

Que. 153. What are the norms of consent requirement in MTP act?

Ans. 153. Only consent of the woman is required to terminate the pregnancy. In case of a minor or mentally ill women, the consent of the guardian is required.

Que. 154. When was the Protection of Children against Sexual Offence Act launched?

Ans. 154. 2012.

Que. 155. As per MTP Act, Who can perform termination of pregnancy up to 12 weeks of gestation?

Ans. 155. A practitioner who has assisted a registered medical practitioner in the performance of 25 cases of MTP of which at least 5 have been done independently in a hospital that have been established or maintained by the government or at a training institute approved for this purpose by the government.

Que. 156. As per MTP Act, who can perform termination of pregnancy up to 20 weeks of gestation?

Ans. 156. Following can perform termination of pregnancy up to 20 weeks of gestation – 

1. A practitioner having post graduate degree or diploma in Obstetrics & Gynaecology.
2. A practitioner who has completed 6 months of house surgency in Obstetrics & Gynaecology.
3. A practitioner who has at least 1 year of experience in the practice of Obs & Gynae at any hospital that has all the facilities. 

Que. 157. What is the norm under MTP act regarding termination of the pregnancy that exceeds 12 weeks but less than 20 weeks?

Ans. 157. The opinion of two registered medical practitioners are required.

Que. 158. What are the indication of termination of pregnancy under MTP Act?

Ans. 158. The indications of termination of pregnancy are as follows – 

1. The continuation of pregnancy involves a risk of the life of the pregnant woman or causes a grave injury to her physical or mental health
2. Rape or incest
3. Failure of contraceptive devices
4. There is a substantial risk that, if child was born, s/he would suffer from such physical or mental abnormality as to be seriously handicapped.

Que. 159. Under MTP Act, where can a pregnancy be terminated?

Ans. 159. MTP can be performed at the following places – 

1. A hospital established or maintained by the government
2. A place approved by the government or district level committee (DLC).

Que. 160. What is the importance of pre-procedure counselling?

Ans. 160. The importance of pre-procedure counselling are followings –

1. It helps woman to decide about the termination of pregnancy
2. It helps woman to choose the method of termination
3. It ensures that the consent of the procedure is given after receiving complete information about the procedure & understanding its implications.
4. It helps a woman to adopt a contraceptive method after the procedure.

Que. 161. When is the return of fertility occur post abortion?

Ans. 161. 11 – 14 days. 

Roughly 75% women ovulate & 6% conceive within 2-6 weeks after abortion, if they are not using contraception.

Que. 162. Which permanent method of contraception is suitable up to 1st trimester abortion?

Ans. 162. Laparoscopic ligation.

Que. 163. Which permanent method of contraception is suitable for all types of abortion?

Ans. 163. Tubectomy (Mini-lap).

Que. 164. When will you prefer to insert Post Abortion IUCD (PAIUCD)?

Ans. 164. Immediately or up to 12 days after confirmation of a completed abortion using the surgical method. With MMA, inserted around day 15 of the process, provided complete POC expulsion is confirmed and risk of infection & other contraindication is ruled out.

Que. 165. What are the importance of post-procedure counselling?

Ans. 165. Following are the importance of post-procedure counselling – 

1. It ensures that the woman has understood the precautions & care needed during the post abortion period & the actions needed in case of complications.
2. It provides an opportunity to counsel for contraception in cases where the woman is not sure about accepting a contraceptive method.
3. It reinforces the need for continuing the use of contraceptive method chosen.

Que. 166. In which cases, establishing the period of gestation may be difficult?

Ans. 166. Establishing the period of gestation may be difficult in the followings – 

1. Woman does not remember the dates of LMP.
2. Conception occurred during lactational amenorrhoea
3. Wrong dates provided by the woman intentionally
4. Missed or incomplete abortions

Que. 167. What are the elements of universal precautions in case of medical termination of pregnancy?

Ans. 167. The elements are – 

1. Handwashing
2. Person protective barriers
3. Aseptic techniques
4. Handling of sharp items
5. Instrument processing
6. Waste disposal.

Que. 168. What is the gestational limit for medical termination of pregnancy by vacuum aspiration?

Ans. 168. Up to 12 weeks.

Que. 169. What is the success rate of vacuum aspiration?

Ans. 169. In first trimester abortions up to 98%.

Que. 170. What are the indications for using vacuum aspiration?

Ans. 170. The indications of vacuum aspiration are followings – 

1. Induced abortion up to 12 weeks gestation
2. Incomplete abortion of up to 12 weeks gestation
3. Missed abortion
4. Hydatidiform mole of up to 12 weeks gestation
5. Removal of decidua with surgical management of an ectopic pregnancy.

Que. 171. What are the contraindications for vacuum aspiration?

Ans. 171. The contraindications are as follows – 

1. Presence of acute cervical, vaginal or pelvic infection
2. Suspicion of uterine perforation
3. Suspicion of ectopic pregnancy.

Que. 172. What is the gestational limit for medical methods of abortion (MMA)?

Ans. 172. Up to 7 weeks (49 days) of LMP.

Que. 173. How many types of vacuum aspiration are in practice?

Ans. 173. 2 types – Manual & Electrical Vacuum Aspiration (MVA & EVA).

Que. 174. What are the advantages of medical methods of abortion (MMA)?

Ans. 174. The advantages of MMA are as follows – 

1. Safe procedure with high success rate in early pregnancy
2. Offers more privacy
3. Feasible with minimum technical assistance
4. Less complications
5. No instrument or anaesthesia required
6. No effect on further fertility if SOP followed.

Que. 175. What are the limitations of MMA?

Ans. 175. Following are the limitations of MMA – 

1. Generally 3 visits required
2. Whole process is a bit longer
3. Duration of bleeding may be 8-13 days which ceases on POC expulsion
4. Drugs used may have side effects
5. Potential risk of foetal malformations if pregnancy continues.

Que. 176. What are the indications of MMA?

Ans. 176. All women with an intrauterine pregnancy, who wish to get their pregnancy terminated within 7 weeks of LMP and are – 

• Willing to pay 3 visits
• Ready for surgical evacuation in case of failure
• Within accessible limit of the facility providing emergency care (CHC/FRU/DH).

Que. 177. What are the contraindications of MMA?

Ans. 177. The contraindications of MMA are – 

1. Confirmed or suspected ectopic pregnancy
2. Moderate to severe anaemia
3. Uncontrolled Hypertension BP > 160/110 mm of Hg
4. Chronic adrenal failure
5. Severe renal, liver or respiratory diseases
6. Uncontrolled seizure disorders 
7. Inherited porphyria
8. Glaucoma
9. Allergy to mifepristone or misoprostol

Que. 178. What is the procedure of the MMA?

Ans. 178. Day 1 – (Day of mifepristone administration)

• Mifepristone (200 mg) administered orally
• Anti-D (50 micro gram) given to Rh negative women.

Day 3 – (Day of Misoprostol administration)

• Administer misoprostol 400 mcg sublingual/buccal/vaginal/ oral route for gestation period up to 7 weeks.
• OR, 800 mcg misoprostol sublingual/buccal/vaginal/oral route for gestation period up to 9 weeks.

Day 15 – (Day of follow up)

• • A clinical H/O women is taken and a pelvic examination is done to ensure the complete expulsion of the products of conception.

• USG is required if the history & examination do not confirm expulsion of POCs. 

Que. 179. What are the different surgical methods of 2nd trimester pregnancy termination?

Ans. 179. Different surgical methods of 2nd trimester abortion are – 

1. Dilatation & Evacuation (D & E)
2. Hysterotomy

Que. 180. What are the steps of medical methods in 2nd trimester abortion?

Ans. 180. Steps are – 

1. Cervical priming
2. Inducing uterine contraction

In India, medical methods for 2nd trimester abortion are not approved by the Government of India.

Que. 181. Name the diseases or health conditions prevented by the use of oral combined contraceptive pills.

Ans. 181. Health conditions prevented are – 

1. Iron deficiency anaemia 
2. Ectopic pregnancies
3. Ovarian cysts & cancers
4. Endometrial cancer
5. PID
6. Benign fibrocystic disease & fibro adenoma of breast

Chapter – 3 – General Epidemiology

Que. 182. What do you mean by term population at risk?

Ans. 182. It is the proportion of population that is susceptible to a disease. It can be defined on the basis of demographic or environmental factors.

Que. 183. What do you mean by point prevalence?

Ans. 183. It measures the frequency of disease at a given point in time. It applies when the data has been collected at one point in time. 

Point prevalence = C/N

Where C is the number of observed cases at time t & N is population size at time t.

Que. 184. What do you mean by period prevalence?

Ans. 184. It measures the frequency of disease over some time. It applies when the data has been collected over a period of time.

Period Prevalence = C+I /N

Where C is the number of observed cases at the beginning of the time period, I is the no. of incident cases that develop during the time period & N is the Size of the population for the same time period.

Que. 185. What are the factors that influence the prevalence?

Ans. 185. The factors that influence the prevalence are – 

1. Number of new cases
2. Duration of illnesses

• If the disease is short, prevalence is reduced.
• If the disease is long, prevalence is increased.

Que. 186. What are the uses of the prevalence data?

Ans. 186. Uses of prevalence data are as follows – 

1. Study chronic diseases
2. Assess health care needs
3. Planning health services
4. Measure occurrence of conditions with gradual onset.

Que. 187. What do you mean by incidence?

Ans. 187. It is the number of new cases of a given disease or health condition in a given period in a specified population. Incidence measures the rapidity with which new cases are occurring. It can be expressed in absolute numbers or in terms of cumulative incidence or incidence density.

Que. 188. What is the other name of incidence density?

Ans. 188. Incidence rate.

Que. 189. What is the other name of cumulative incidence?

Ans. 188. Attack rate.

Que. 190. How will you calculate cumulative incidence (CI)?

Ans. 190. CI = No. of new cases/Population at risk at the beginning * 1000 or 10000 or 1 lakh

Assumes that the entire population at risk at the beginning was followed-up for the time- period of observation.

Que. 191. How will you calculate the incidence rate?

Ans. 191. Incidence rate = No. of new cases/Total person time of observation* 1000 or 10000 or 1 lakh.

Que. 192. What are the uses of incidence data?

Ans. 192. Following are the uses of the incidence data – 

1. Describe trends in disease
2. Evaluate the impact of primary preventive programs.

Que. 193. What is the relation between prevalence and incidence?

Ans. 193. Prevalence (P) = Incidence (I) * duration (D).

Que. 194. What do you mean by case fatality rate?

Ans. 194. It is the ratio of numbers of deaths from a disease to the no. of cases due to that disease. Case fatality rate reflects severity of the disease.

Que. 195. What are the types of the descriptive studies?

Ans. 195. The types of descriptive studies are as follows – 

1. Case report
2. Case series
3. Ecological studies
4. Cross-sectional study

Que. 196. What do you mean by case reports?

Ans. 196. Case reports include detailed presentation of a single case of new or unfamiliar diseases or with rare manifestations. Case reports may be used to generate hypothesis regarding patho-physiological mechanism.

Que. 197. What do you mean by case series?

Ans. 197. It is the study of large group of patients (i.e. >10) with a particular disease.

Que. 198. What are the advantages of case series?

Ans. 198. The advantages of case series are – 

1. Larger number of cases may allow the investigator to assess the play of chance.
2. It is a common way of delineating the clinical pictures of a disease.

Que. 199. What is the disadvantage of case series?

Ans. 199. Do not have a comparison group.

Que. 200. What is the unit of study or analysis in an ecological study?

Ans. 200. Group or population. No individual level information is gathered on the distribution of exposure & disease.

Que. 201. What does an ecological study relate?

Ans. 201. It relates whether populations with high rates of the disease also have high frequency of the suspected exposure.

Que. 202. What is the unit of observation or analysis in a cross-sectional study?

Ans. 202. The individual.

Que. 203. What do you mean by cross-sectional study?

Ans. 203. It is the observation of a cross-section of a population at a single point in time. Unit of observation or analysis being an individual. It collects information about disease burden, therefore also called PREVALENCE STUDIES. Observation is made for the presence of one or more outcomes or one or more exposures.

Que. 204. What are the uses of cross-sectional study?

Ans. 204. Followings are the uses of cross-sectional study – 

1. Estimates prevalence of disease or their risk factors
2. Study distribution of health problem by time, place and person
3. Sets priorities for disease control
4. Generates hypothesis 
5. Estimates evolving trends of health problems.

Que. 205. What are the advantages of cross-sectional study?

Ans. 205. The advantages of cross-sectional study are as follows – 

1. Fairly quick & easy to perform.
2. Less expensive.

Que. 206. What are the limitations of cross-sectional study?

Ans. 206. The limitations of cross-sectional study are as follows – 

1. Not useful to study disease etiology.
2. Not suitable for the study of rare diseases
3. Identifies both new and old cases.

Que. 206. In which epidemiological study, exposure and outcome are examined at the same time?

Ans. 206. Cross-sectional study.

Que. 207. Which epidemiological study is useful to measure the burden or magnitude of a disease or risk factor?

Ans. 207. Cross-sectional study.

Que. 208. Which epidemiological study design does not employ comparison group to answer the primary study objectives?

Ans. 208. Cross-sectional study.

Que. 209. Risk factors of the study cannot be assessed by which epidemiological study?

Ans. 209. Descriptive study.

Que. 210. Which study design does provide group exposure & group response/outcome without knowing the individual exposure and response for a specific health problem?

Ans. 210. Ecological study.

Que. 211. Which type of study is a population census?

Ans. 211. Cross-sectional survey.

Que. 212. Which are the characteristics of analytical studies?

Ans. 212. The characteristics of analytical studies are – 

1. Investigator does not assign the exposure
2. There is invariably a comparison group.

Que. 213. What do you mean by Cohort?

Ans. 213. Group of people sharing common characteristics called cohort e.g. birth cohort.

Que. 214. What are the types of cohort study?

Ans. 214. The types of cohort study are as follows – 

1. Prospective cohort study
2. Retrospective cohort study
3. Ambispective cohort study

Que. 215. What are the elements of cohort study?

Ans. 215. The elements of cohort study are as follows – 

1. Selection of study populations
2. Gathering baseline information
3. Follow up
4. Analysis

Que. 216. What are the choices of comparison group in cohort study?

Ans. 216. The choices of comparison group in cohort study are as follows – 

1. Internal comparison group e.g. unexposed persons in the population
2. External comparison group when internal comparison group is not available.

Que. 217. How will you calculate Relative Risk?

Ans. 217. RR = Incidence of disease among exposed/ Incidence of disease in unexposed.

                       = (a/a+b) /(c/c+d).

Que. 218. What interpretation will you make if RR <1?

Ans. 218. Incidence in exposed is lower than in unexposed, meaning that exposure is negatively associated with the disease.

Que. 219. What interpretation will you make if RR = 1?

Ans. 219. Incidence in exposed and unexposed is equal, meaning that exposure is not associated with the disease.

Que. 220. What interpretation will you make if RR >1?

Ans. 220. Incidence in exposed is greater than that in unexposed, meaning that exposure is positively associated with the disease.

Que. 221. How is the progression of a cohort study?

Ans. 221. From Cause/exposure to effect or outcome.

Que. 222. What are the strengths of cohort study?

Ans. 222. Followings are the strength of cohort study – 

1. Incidence can be calculated
2. Examines multiple outcomes for a single exposure
3. Clarity of temporal sequence
4. Good for investigating rare exposures.

Que. 223. What are the weaknesses of cohort study?

Ans. 223. Followings are the weaknesses of a cohort study – 

1. Expensive & time consuming
2. Not good for rare disease
3. Not good for diseases with a long latency
4. Differential loss to follow up can introduce bias.

Que. 224. How is the progression of a case control study?

Ans. 224. From effect/outcome to cause/exposure. It is a backward study.

Que. 225. What are the elements of a case control study?

Ans. 225. The elements of a case control study are – 

• Selection of cases

• Selection of controls

• Information on exposure

• Analysis.

Que. 226. What are the strengths of a case control study?

Ans. 226. Following are the strengths of a case control study – 

• Good for examining rare diseases or diseases with a long latency

• Quick to conduct and inexpensive

• Requires comparatively few subjects

• Multiple exposures or risk factors can be examined.

Que. 227. What are the weaknesses of case control study?

Ans. 227. Following are the weaknesses of case control study – 

1. 1. Susceptible to recall bias
   2. Selection of an appropriate comparison group may be difficult

• Relates of disease in exposed and unexposed individuals cannot be determined.

Que. 228. In which epidemiological studies, exposure is not assigned by the investigator?

Ans. 228. Descriptive & Analytical studies.

Que. 229. In which epidemiological studies, exposure is assigned by the investigator?

Ans. 229. Experimental study.

Que. 230. What do you mean by randomized controlled clinical trials?

Ans. 230. A randomized controlled clinical trial is a planned experiment designed to assess the efficacy of prophylactic/diagnostic/therapeutic agents, devices, regimens, procedures etc. applied to human subject.

It essentially involves comparing the outcomes in a group of patients treated with a test treatment with those observed in a comparable group of patients receiving a control treatment where patients in both groups are enrolled in a prospective study treated or exposed to intervention and followed over same period.

Que. 231. What are the objectives of clinical trials?

Ans. 231. These are generally conducted to evaluate new forms of therapy, diagnostic procedures or preventive methods.

Que. 232. Which is the heart of the randomized controlled clinical trials?

Ans. 232. Randomization. 

Que. 233. What do you mean by randomization?

Ans. 233. Randomization ensures that participants have an equal chance to be assigned to one of two or more groups.

Que. 234. Mention the types of blinding.

Ans. 234. The types of blinding are – 

1. Participants (Single blinding)
2. Participants & Investigator (double blinding) & 
3. Participants, Investigators & Analysts (Triple blinding).

Que. 235. What are the objectives of phase I to phase IV clinical trials?

Ans. 235. The objectives of phase I-IV clinical trials are as follows – 

Que. 236. What are the sample size & participants of phase I – IV clinical trials?

Ans. 236. The sample size & participants of phase I-IV clinical trials are as follows – 

Que. 237. What are the advantages of RCTs?

Ans. 237. Following are the advantages of RCTs – 

1. The only effective method to control selection bias
2. Controls confounding bias without adjustment
3. Facilitate effective blinding
4. Maintains advantages of cohort studies.

Que. 238. What are the disadvantages of RCTs?

Ans. 238. Following are the disadvantages of RCTs – 

1. Complex & expensive
2. Lack representativeness – volunteers differ from population of interest
3. Immense ethical challenge.

Que. 239. What do you mean by Placebo?

Ans. 239. A pharmacologically inactive agent that the investigators administer to participants in control group of a trial is called Placebo.

Que. 240. What is the purpose of double blinding in a RCT?

Ans. 240. To avoid observer & participants bias.

Que. 241. What do you mean by external validity?

Ans. 241. Obtaining an estimate that is generalizable to relevant study population in an epidemiological study is called external validity.

Que. 242. What do you understand by term bias?

Ans. 242. Any process that tends to produce results that depart systemically from the values in an epidemiological study.

Que. 243. Which type of bias does result when systematic selection of more number of exposed participants with high risk of outcome in a cohort study will be done?

Ans. 243. Selection bias.

Que. 244. What do you mean by confounding?

Ans. 244. The effect of the exposure of interest on the outcome is distorted because of the effect of extraneous factors that are related to both the exposure and outcome. This phenomenon is called confounding.

Que. 245. Biases can occur during which stage of epidemiological study?

Ans. 245. At any stage from study design to analysis.

Que. 246. How will you minimize the information bias?

Ans. 246. The information bias may be minimized by – 

• Precise operational definitions of variables

• Detailed measurement protocols

• Repeated measurement on key variables

• Training, certification & recertification

• Data audits

• Data cleaning

• Re-running all analysis prior to all publication.

Que. 247. What do you mean by Chance?

Ans. 247. Variability in estimation due to unknown or uncontrollable factors is called chance.

Que. 248. Which are the methods used to alleviate confounding during data analysis in an epidemiological study?

Ans. 248. Stratification & Multivariate analysis.

Que. 249. What do you mean by Internal Validity?

Ans. 249. Obtaining an accurate estimate of disease frequency and effect of exposure on health outcome in study population is known as Internal Validity.

Que. 250. Which type of biases are prevented by blinding in an epidemiological study?

Ans. 250. Selection bias & Information bias.

Que. 251. What do you mean by term validity?

Ans. 251. The ability of a tool to correctly measure what it is supposed to measure is called validity.

Que. 252. Which methods are used to address for known confounders at the designing stage of a study?

Ans. 252. Restriction, Matching & Randomization.

Que. 253. What do you mean by term prevarication?

Ans. 253. Systematic distortion of the truth by study subject is called prevarication.

Que. 254. What are the effects of confounding in epidemiological studies?

Ans. 254. The effects of confounding are – 

1. May simulate an association that does not exist
2. May hide an association that does exist
3. May change the direction of an effect
4. May increase or decrease the strength of association.

Que. 255. How will you deal with selection bias during designing stage of a study?

Ans. 255. Selection bias during designing stage of a study can be dealt with – 

1. Use of incident cases, not prevalent cases
2. In Case Control studies – 

• Use population based design
• Apply same eligibility criteria for selecting cases and controls
• Both cases and controls undergo the same diagnostic procedures & intensity of disease surveillance.

Que. 256. How will you deal with selection bias during data collection stage of the study?

Ans. 256. The selection bias during data collection stage of the study may be dealt with – 

1. Minimize the non-response, non-participation and loss to follow up (Cohort studies)
2. Keep a record on all losses and collect baseline data on them.
3. Make sure that diagnosis of disease is not affected by exposure status (Blinding).

Que. 257. How will you deal with selection bias during analysis stage of study?

Ans. 257. The selection bias during analysis stage of the study may be dealt with – 

1. Compare non-responders/dropouts with responders/non-dropouts with respect to baseline variables
2. Use study results and external information to deduce the direction of biases and assess magnitude of biases.

Que. 258. What are the important features of Random Error?

Ans. 258. In random error,

1. No sample is likely to give us results which are exactly the same as the truth in local population.
2. No two samples drawn from the same population are likely to give us the same results
3. It will not occur if we study the entire population.

Que. 259. What do you mean by Precision?

Ans. 259. The ability of a measurement process to diagnose correctly as positive those who really have the disease.

Que. 260. What is the other name of randomization?

Ans. 260. Random allocation.

Que. 261. In which type of epidemiological study, loss to follow up or attrition is a problem?

Ans. 261. Cohort studies.

Que. 262. In which type of study design, it is sometimes difficult to establish temporal association?

Ans. 262. Cross-sectional study.

Que. 263. Which is the most likely reason for failure to establish a cause –effect relationship with small sample size?

Ans. 263. Beta error or type II error.

Que. 264. Which is indicative of the strength of association in a cause effect relationship?

Ans. 264. The magnitude of OR/RR.

Que. 265. If OR/RR=1, what does it indicate?

Ans. 265. There is no cause effect relationship.

Que. 266. What do you mean by Berkson’s bias?

Ans. 266. This is the bias due to different rates of admission to hospitals for those who have more than one disease.

Que. 267. What does cross sectional study give as a measure of risk?

Ans. 267. Prevalence odds ratio.

Que. 268. What are the disadvantages of cross-sectional vs. case control study?

Ans. 268. Huge logistics & large sample size.

Que. 269. What is the tool for the control of confounder in experimental design?

Ans. 269. Randomization.

Que. 270. What is the measure of risk in a cohort study?

Ans. 270. Relative risk.

Que. 271. Prevalence will affect the ______________________ of a test?

Ans. 271. Predictive value.

Que. 272. What is plotted along the Y axis in ROC curve?

Ans. 272. Sensitivity.

Suggested Further Readings – 

• K. Park; Park’s textbook of Preventive & Social Medicine, 27th edition, 2023

• Shah A M; Basic course in Biomedical Research –review, ICMR NME.

• R. Bhalwar; textbook of Public health & Community Medicine, AFMC-WHO, 1st  edition, 2009

• AH Suryakantha; Community Medicine with Recent Advances, 3rd Edition.

• Mahajan & Gupta; Textbook of Preventive & Social Medicine; 4th edition