20 High Yield PSM Flashcards NEET PG 2026

Flashcard 1

Tools of Measurement in Epidemiology 

• Rate
• Ratio
• Proportion
  • To express the frequencies
  • Each of these has a numerator and a denominator.
• In rate - the numerator is part of the denominator.
  • Multipliers can be 1000 or 10,000 or one lakh.
• Proportion - numerator is part of the denominator.
  • Multiplier in proportion is always 100.
• Ratio - numerator is not a part of the denominator.
  • Sex ratio = Number of females per 1000 number of males
  • So, the numerator is not a part of the denominator.

Flashcard 2

Incidence Vs Prevalence

Flashcard 3

Types of Cohort Study 

• Prospective cohort study
  • Concurrent - moving forward with time.
• Retrospective cohort study
  • Non- concurrent study.
  • We are moving at the opposite time.
• Mixed cohort study
  • Both retrospective + prospective.
• A group of nurses who do not have Cancer or CVD - cohort.
• A cohort study always compares exposed with non-exposed.
• Obesity is exposed – a high-risk factor.
• Lean - non-exposed
• The study is going forward → This is a prospective cohort study.

Flashcard 4

The measure of Strength of the Association of Cohort Study

1. Relative risk (Risk Ratio)
2. Attributable risk
3. Population Attributable Risk - PAR

Relative risk

• Association between smoking and CVD
• 2*2 table
• Relative risk or risk ratio = incidence among exposed / incidence among non-exposed.
  • Incidence among exposed = a / a+b
  • Incidence among non-exposed = c / c+d

Interpretation of relative risk

• Relative risk
  • > 1 - positive association (risk factor)
  • = 1 - no association
  • < 1 - negative association
• Suppose the relative risk is 4.5 - that means those who smoke are at 4.5 times higher risk of developing CVD.
• Positive association means it is a risk factor.
• Negative association means an inverse association, or it is a protective factor.
• In a study, the association between herbal tea and diabetes was studied, and the risk ratio was found to be 0.8. RR < 1 → This means herbal tea is a protective factor for diabetes.

Attributable risk 

AR = (incidence among exposed - incidence among non-exposed) / incidence among exposed * 100

• Expressed as a percentage.
• Suppose AR is 75% in a study of smoking and lung cancer, that means 75% of lung cancers are attributed to smoking.
• Of use to epidemiologists

Population Attributable Risk - PAR

PAR = incidence among the total population - incidence among exposed / incidence among total population * 100

• Total population = a+b+c+d
• incidence among total population = a +c / a+b+c+d
• incidence among non-exposed = c / c+d

PAR = [(a+c/a+b+c+d)-(c/c+d)]/(a +c/a+b+c+d)* 100

Flashcard 5

Case-Control Study 

• Type - observational analytical study.
• Basic design: comparison between diseased vs non-diseased.
• Start at present time
• Cases - diseased
• Controls - non- diseased
• Study proceeds retrospectively i.e. backward
• In the retrospective cohort study also, we start at the present time and move backward, but there, we were comparing exposed and nonexposed.
• In case-control, study is started at present time, compare diseased v/s non diseased at present time

Flashcard 6

Measure of Strength of Association of Case-Control Study 

• Odds ratio or cross-product ratio

Odds ratio = ad/bc

• > 1 - positive association (risk factor)
• = 1 - no association
• < 1 - negative association (protective factor)

Example

• Odds ratio = ad/bc = 30*30/ 20*20 = 9/4 = 2.5
• Here, odds ratio = 2.5 which is > 1, so positive association
• OR : provides an estimate of relative risk.

Flashcard 7

Meta-analysis

• One step ahead and perform quantitative analysis: Meta-Analysis.
• It is a quantitative approach for systematically combining previous research to arrive at conclusions about the body of research.

Steps of Systematic review

Step 1 Defining the review question and eligibility criteria

Step 2 Searching for studies

Step 3 Selecting the studies

Step 4 Data extraction

Step 5 Data synthesis

Step 6 Interpretation of the results

Steps of Meta-Analysis

Flashcard 8

Errors

Flashcard 9

Types of Blinding

Flashcard 10

Steps of investigation of an epidemic

• Verification of diagnosis
  • Most important step
• Confirmation of the existence of an epidemic
• Define the population at risk.
• Rapid search for all cases and their characteristics
• Data analysis
• Formulation of hypothesis
  • Work of descriptive epidemiology
• Testing of hypothesis
  • Analytical study
    • All of those who have suffered have become the cases and compare them with those who have not become the cases to answer why and how.
• Evaluation of etiological factors
• Further investigation of the population at risk
• Writing a report

Flashcard 11

Isolation vs Quarantine

Modified quarantine: partial limitation in freedom of movement. Exclusion of children from school. Health authorities can also apply the term quarantine for any ship or vehicle supposed to be the carrier of a disease.

Flashcard 12

Difference between PQLI and HDI

Flashcard 13

Iceberg Phenomenon of Disease

Flashcard 14

Live Vaccine

• A live organism is injected into the body in attenuated form.
• Attenuated form: Reduced the organism's virulence (killing power), but antigenicity (antibody-producing capacity) is maintained.
• Single vaccine doses are sufficient to produce the required immunity. Except for the Oral polio vaccine. In OPV other than primary, booster doses are required to produce sufficient immunity.

Killed Vaccine

• Organisms are injected in killed forms
• Killed by
  • Heat
  • Chemicals (formalin)
• Major antigen persists, minor antigen destroyed.
• Given as multiple doses, booster doses

Flashcard 15

Open Vial Policy 

It states that vaccine vials opened in session sites can be used in more than one immunization session upto 4 weeks/ 28 days. Four conditions needed to be fulfilled:

1. The Expiry date has not passed
2. Vaccines are stored strictly under an appropriate temperature (+2 to +8°C) range during transportation and storage at cold chain point
3. Aseptic technique has been used to withdraw all doses.
4. Vaccine vial monitor has not reached the discard point
5. Vaccine vial septum is not contaminated

Vaccines following Open Vial Policy: All are Liquid vaccines (All t series vaccine + PIO + Jenvac)

• Hepatitis B
• DPT
• Pentavalent
• Td, Tt
• Rotavac
• PCV
• IPV
• OPV
• Jenvac – killed JE

Vaccines that do not follow open vial policy are known as reconstituted vaccines.

• BCG, Measles, MR, JE (Live), Yellow fever, covid vaccine

Flashcard 16

Storage of Vaccines in Cold Chain 

• The vaccines must be maintained at proper temperatures and conditions from the point of manufacture to the point of use.
• Cold chain temperature in India is +2° to +8°
• OPV (long-term storage) and yellow fever vaccine in freezing conditions: –15° to – 25°
• The maximum chance of failure of the cold chain is seen at the subcenter and Village levels; thus, vaccines are not stored.

Flashcard 17

• Ring Immunization: Any suspected case in the center, vaccine the susceptible children within a 100-yard radius of the infected case
• Herd Immunity: Break in the chain of disease transmission.
• Threshold cut off: Measles, Pertussis, Chickenpox >90%
• Polio, Mumps: 80-85%
• No role of herd immunity in tetanus and rabies.
• Fully immunized: A child who has completed all due vaccines till 1 year of age among 12-23 months
• Completely immunized: A child who has completed all due vaccines till 2 years of age among 5-year-olds.
• BCG: No protection from pulmonary TB
• Measles:
  • >90% with one dose
  • >99% with two doses (India adopted the 2 doses of measles vaccine strategy called Accelerated Measles Mortality Reduction Strategy)
• Rubella >95% (Vaccine with highest efficacy with single dose)

Flashcard 18

First Generation IUD

First generation IUD (Non medicated): Inert - No longer used.

Second Generation IUDs

• Second generation IUDs (medicated)
• Copper-containing IUDs
• CuT 380 A or Ag, NOVA T, multiload (ML-Cu-250, ML-Cu-375)

The two copper devices that are freely available under the National Family Welfare Programme: CuT 380 A and CuT 375. 380, 375 means the area of copper wire that is wound around the stem in mm². 

Flashcard 19

DIFFERENCE BETWEEN COW’S MILK, BUFFALO MILK AND BREAST MILK

WHO Classification of Xerophthalmia

• Chlorine also oxidizes Iron, Manganese and Hydrogen sulfide and controls algae, slime organisms, and AIDS coagulation.
• Most common presenting symptom: Night blindness.
• Most common presenting manifestation: Night blindness.
• First symptom of vitamin A deficiency: Night blindness.
• Most common indicator for Vitamin A deficiency: Bitot's spots
• Most common clinical sign for screening: Bitot's spots
• Most sensitive screening test: Serum Retinol level
• First clinical sign: Conjunctival xerosis
• Most specific presentation: Bitot spot
• Reversible till which stage: X2
• Irreversible stage: X3A and X3B

Flashcard 20

Ariboflavinosis Triad 

As in the first image, the Magenta red Tongue is seen in vitamin B2 Deficiency. Also known as Geographical Tongue/Glossitis. As in the second image, it also presents cheilosis. As in the third image, it also presents Angular Stomatitis. This is the most specific presentation. This is Vitamin B3 deficiency (Niacin deficiency). Niacin deficiency presents with Pellagra

6 D's

• Diarrhea
• Dermatitis
• Dementia
• Depression
• Delirium
• Death

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