INI-CET 2025 - Community Medicine PYQs Practice Questions

Q: In a village of 100 children, 10 children have a past history of measles (i.e., they are not at risk now), 20 new cases of measles were reported this year. What is the incidence of measles in this population for the year?

22.22 %. ***22.22 %*** - Incidence is calculated as the ratio of **new cases** (20) to the **population at risk** (susceptible population) over the specified period. - The **population at risk** is the total population (100) minus those who are already immune (10), making the denominator 90. Incidence = (20/90) × 100 = **22.22 %**. *20 %* - This result is obtained by incorrectly using the **total population** (100) as the denominator (20/100 × 100), ignoring the already immune group. - Using the total population in the denominator leads to an underestimate of the true **attack rate** or incidence among the susceptible group. *10 %* - This figure represents the proportion of children who had suffered from measles in the past (10/100), reflecting a form of **past prevalence**, not incidence. - Incidence focuses exclusively on the **new cases** that developed within the year. *30 %* - This percentage represents the **cumulative prevalence** at the end of the year, including both old (10) and new (20) cases, divided by the total population (30/100). - Incidence requires the denominator to be the **population at risk** (those who could develop the disease), not the total population. [Practice more Community Medicine PYQs on OnCourse]

Q: According to WHO, which rapid molecular test is recommended as the initial diagnostic investigation for tuberculosis (TB) spine?

CBNAAT. ***CBNAAT*** - The **WHO** strongly recommends **CBNAAT (GeneXpert or Truenat)** as the **initial rapid molecular diagnostic test** for extrapulmonary TB (EPTB), including **TB spine (Pott's disease)**, due to its rapid turnaround time and high sensitivity. - CBNAAT simultaneously detects **Mycobacterium tuberculosis** DNA and identifies resistance to **Rifampicin**, providing critical information for prompt treatment initiation, typically within 2 hours. - This rapid molecular test is preferred over traditional methods for initial diagnosis to enable early treatment decisions. *Incorrect: X-ray* - X-rays are imaging studies useful for detecting features like **vertebral destruction**, **paraspinal shadow**, and collapse leading to **gibbus deformity**, but they are not molecular diagnostic tests. - While X-rays are included in the diagnostic workup, they cannot confirm the presence of the organism or detect drug resistance, which is why they are not the WHO-recommended initial molecular test. *Incorrect: CT scan* - CT scans offer superior visualization of subtle bony changes, extent of destruction, and delineating **paraspinal cold abscesses**, often used for staging and guiding intervention. - Like X-ray, CT is an **imaging modality** that assists in identifying structural changes but is not a molecular diagnostic test and cannot provide microbiological confirmation or drug resistance information. *Incorrect: Culture and sensitivity* - **Culture (e.g., Lowenstein-Jensen, MGIT)** is considered the **gold standard** for definitive diagnosis and comprehensive Drug Susceptibility Testing (DST). - However, culture results are slow (taking 4–8 weeks), which delays crucial management decisions, leading the WHO to prioritize **rapid molecular tests** like CBNAAT for **initial diagnosis** over culture, though culture remains important for comprehensive DST. [Practice more Community Medicine PYQs on OnCourse]

Q: In a given population: - less than 15 years: 6000 - 15 to 64 years: 12000 - 65 years and above: 2000 Calculate the dependency ratio.

66 %. ***66 %*** - The **Dependency Ratio** measures the ratio of the economically dependent population to the economically productive population, usually expressed as a percentage. - **Dependent Population** (aged < 15 and ≥ 65): 6000 + 2000 = **8000** - **Productive Population** (aged 15-64): **12000** - **Dependency Ratio**: (8000 / 12000) × 100 = **66.67%** (rounded to 66%) *Incorrect: 33 %* - This figure is significantly lower than the true ratio and results from calculating the ratio of the dependent population to the **total population**, which is not the standard definition of the Dependency Ratio. - 33.3% represents the dependent population (8000) as a proportion of the total population (20000), not the dependency burden on the working population. *Incorrect: 50 %* - This result is obtained if only the young dependent group is used in the numerator (Young Dependency Ratio = 6000 / 12000 = **50%**). - However, the total Dependency Ratio must account for **both young and old dependents** to accurately reflect the economic burden. *Incorrect: 75 %* - Obtaining 75% would require the dependent population to be 9000 (i.e., 9000 / 12000), which is higher than the actual 8000 dependents. - This option represents an overestimation of the dependent burden on the working population. [Practice more Community Medicine PYQs on OnCourse]

Q: In a study done in a hospital, patients were categorized into three groups based on disease prevalence (Low, Medium, High), and individuals were then randomly selected from each group. What type of sampling is this?

Stratified random sampling. ***Correct: Stratified random sampling*** - This method involves dividing the population into non-overlapping subgroups (**strata**) based on a characteristic (here, disease prevalence: Low, Medium, High). - Subsequently, a **simple random sample** is drawn from *each* stratum independently to ensure representation from all groups. - This ensures that each subgroup is adequately represented in the final sample, making it ideal when the population has distinct subgroups. *Incorrect: Simple random sampling* - Every individual in the entire population has an equal and independent chance of being selected. - It does not involve dividing the population into specific subgroups or categories before selection. - This method may underrepresent or overrepresent certain subgroups by chance. *Incorrect: Systematic random sampling* - This involves selecting every *k*th element after a random start point, where *k* is the sampling interval (Population Size/Sample Size). - Like simple random sampling, it does not involve creating predefined strata based on characteristics like disease prevalence. - It's a simpler alternative to simple random sampling but doesn't ensure representation of specific subgroups. *Incorrect: Cluster random sampling* - The population is divided into natural groupings (**clusters**), such as geographical areas or schools. - Unlike stratification, entire clusters are randomly selected, and *all* individuals within the selected clusters (or a random sample thereof) are included in the study. - This differs from stratified sampling where we sample from ALL strata; in cluster sampling, we sample only SOME clusters. [Practice more Community Medicine PYQs on OnCourse]

Question 1

In a village of 100 children, 10 children have a past history of measles (i.e., they are not at risk now), 20 new cases of measles were reported this year. What is the incidence of measles in this population for the year?

Accepted Answer

22.22 %

Answer

10 %

Answer

30 %

Answer

20 %

Question 2

According to WHO, which rapid molecular test is recommended as the initial diagnostic investigation for tuberculosis (TB) spine?

Accepted Answer

CBNAAT

Answer

X-ray

Answer

CT scan

Answer

Culture and sensitivity

Question 3

According to NPCBVI, blindness is defined as:

Accepted Answer

Presenting visual acuity < 3/60 in better eye

Answer

Corrected visual acuity 6/60 in better eye

Answer

Corrected visual acuity 3/60 in better eye

Answer

Presenting visual acuity 6/60 in better eye

Question 4

In a given population:
- less than 15 years: 6000
- 15 to 64 years: 12000
- 65 years and above: 2000

Calculate the dependency ratio.

Accepted Answer

66 %

Answer

50 %

Answer

75 %

Answer

33 %

Question 5

In a study done in a hospital, patients were categorized into three groups based on disease prevalence (Low, Medium, High), and individuals were then randomly selected from each group. What type of sampling is this?

Accepted Answer

Stratified random sampling

Answer

Systematic random sampling

Answer

Cluster random sampling

Answer

Simple random sampling

Question 6

In statistics, centiles and quartiles are considered as:

Accepted Answer

Measures of location/position

Answer

Measures of dispersion

Answer

Measures of central tendency

Answer

Measures of correlation

Question 7

Which of the following is incorrectly matched with respect to the statistical parameter?

Accepted Answer

Mean, median - Dispersion

Answer

Moments - Skewness

Answer

Standard error - Variation

Answer

Correlation coefficient - Relationship

Question 8

In a Primary Health Centre (PHC), a study was done on diabetic patients. Mean weight was recorded before and after 6 months of dietary intervention. Which statistical test should be used to determine significance?

Accepted Answer

Paired t-test

Answer

Chi-square test

Answer

Unpaired t-test

Answer

ANOVA

Question 9

Which of the following is not classified under High-Risk Groups for HIV as per NACO guidelines?

Accepted Answer

Truck drivers

Answer

Men having sex with men (MSM)

Answer

Injecting drug users (IDUs)

Answer

Female sex workers (FSW)

Question 10

RMNCH+A is a strategy that provides comprehensive healthcare across all life stages. Which of the following is NOT included under RMNCH+A?

Accepted Answer

Geriatric population

Answer

Family planning

Answer

Adolescent health

Answer

Maternal and Child Health (MCH) care

INI-CET 2025 — Community Medicine