A cohort study was conducted among 200 men aged 20–30 years in Rampur village. Out of 200, 120 men were tobacco users and rest 80 didn’t take any form of tobacco. At the end of one year, 40 men among tobacco users and 10 men among non-tobacco users developed tuberculosis. The incidence of tuberculosis among tobacco users is:
The data regarding two exposures A and B, associated with a disease X in a community is given below: Which one of the following assertions and the reasons given is correct?
Which of the following types of study designs will be most appropriate to find out the association between mobile phone radiation exposure and cancer?
The villages A and B have the following age compositions: Which of the following is the best indicator for comparing the death rates of these two villages?
Which of the following is/are suggested by rising incidence rates of any disease? 1. Need for a new disease control programme 2. Improvement in reporting practices 3. Change in the etiology of the disease Select the correct answer using the codes given below:
What constitutes the denominator in ‘Total Dependency Ratio’?
By which one of the following studies can relative risk be best calculated?
Orthotolidine (OT) test is done for determining residual free chlorine quantitatively and qualitatively. What is the colour of the solution after adding OT which indicates presence of free chlorine?
Consider the following in respect of Navjyot Shishu Suraksha Karyakram (NSSK): 1. It is a programme aimed to train health personnel in basic newborn care and resuscitation 2. It addresses care at birth issues (i.e. prevention of hypothermia, prevention of infection, early initiation of breastfeeding and basic newborn resuscitation) 3. The objective is to have a trained health person in basic newborn care and resuscitation at every delivery point Which of the statements given above are correct?
The most important indicator for assessment of impact in Salt Iodization Programme is:
UPSC-CMS 2018 - Community Medicine UPSC-CMS Practice Questions and MCQs
Question 11: A cohort study was conducted among 200 men aged 20–30 years in Rampur village. Out of 200, 120 men were tobacco users and rest 80 didn’t take any form of tobacco. At the end of one year, 40 men among tobacco users and 10 men among non-tobacco users developed tuberculosis. The incidence of tuberculosis among tobacco users is:
- A. 33.3 per 100 men/ year (Correct Answer)
- B. 30.0 per 100 men/ year
- C. 12.5 per 100 men/ year
- D. 25.0 per 100 men / year
Explanation: ***33.3 per 100 men/year*** - **Incidence of tuberculosis among tobacco users** is calculated as (Number of new cases among tobacco users / Total number of tobacco users) × 100. - In this study, (40 / 120) × 100 = **33.3 per 100 men/year**. - This is the correct application of the **incidence rate formula** for the exposed group. *30.0 per 100 men/year* - This figure does not correspond to any standard epidemiological calculation for this study. - It may result from mathematical error or confusion with other rates. - The correct calculation for tobacco users yields 33.3, not 30.0. *12.5 per 100 men/year* - This value represents the **incidence among non-tobacco users** (10/80 × 100 = 12.5). - This answers a different question - the incidence in the unexposed group. - The question specifically asks for incidence among **tobacco users**, not non-users. *25.0 per 100 men/year* - This represents the **overall incidence** in the entire cohort: (40 + 10) / (120 + 80) × 100 = 50/200 × 100 = 25.0. - This is the total population incidence, not specific to tobacco users. - The question asks for incidence among tobacco users specifically, which requires using tobacco users as the denominator.
Question 12: The data regarding two exposures A and B, associated with a disease X in a community is given below: Which one of the following assertions and the reasons given is correct?
- A. Cannot decide, as the precedence of exposure in the community has not been mentioned
- B. Preference to control exposure A, because it has a higher population attributable risk (Correct Answer)
- C. Preference to control exposure B, because it has a higher attributable risk
- D. Preference to control exposure B as it has a higher relative risk
Explanation: ***Preference to control exposure A, because it has a higher population attributable risk*** - **Population Attributable Risk (PAR)** quantifies how much of the disease incidence in the *total population* can be attributed to a specific exposure. When deciding on public health interventions, controlling the exposure with the highest PAR will have the **greatest impact on reducing the disease burden** in the community. - In this case, exposure A has a PAR of 70%, meaning 70% of disease X cases in the community can be prevented by eliminating exposure A, while exposure B has a PAR of 50%. Therefore, prioritizing preventive measures for exposure A is more effective from a public health perspective. *Cannot decide, as the precedence of exposure in the community has not been mentioned* - The decision on which exposure to control is primarily based on its **potential impact on public health**, which is best reflected by the Population Attributable Risk (PAR). - The "precedence of exposure" (e.g., which exposure came first or is more fundamental) is not typically the primary factor for public health priority setting when quantitative measures like PAR are available. *Preference to control exposure B, because it has a higher attributable risk* - **Attributable Risk (AR)**, also known as the attributable fraction among the exposed, indicates the proportion of disease among *exposed individuals* that is due to the exposure. While B has a higher AR (90% vs. 80%), this metric does not account for the prevalence of the exposure in the overall population. - A high AR for an exposure that is rare in the population might have less overall public health impact than a lower AR for a very common exposure, which is why PAR is a better guide for population-level interventions. *Preference to control exposure B as it has a higher relative risk* - **Relative Risk (RR)** indicates the strength of the association between an exposure and a disease (i.e., how many times more likely exposed individuals are to develop the disease compared to unexposed individuals). Exposure B has a higher RR (10 vs. 5). - While a higher RR signifies a stronger association, it does not tell you the overall impact on the *community*. An exposure with a very high RR but low prevalence might contribute less to the total disease burden in the population than an exposure with a moderate RR but high prevalence, which is again why PAR is preferred for public health decision-making.
Question 13: Which of the following types of study designs will be most appropriate to find out the association between mobile phone radiation exposure and cancer?
- A. Cross-sectional
- B. Case-series
- C. Single-arm interventional
- D. Case-control (Correct Answer)
Explanation: ***Case-control*** - **Among the given options**, case-control studies are most appropriate for investigating the association between mobile phone radiation exposure and cancer. - **Case-control studies** are efficient for investigating rare outcomes like cancer, by comparing exposure histories between individuals with the disease (cases) and those without (controls). - This design allows for studying factors potentially linked to disease despite **long latency periods**. - However, note that **cohort studies** would be even more ideal for this research question as they better establish temporal relationships and minimize recall bias, which is why major studies like the INTERPHONE study used cohort designs. But cohort studies are not among the options provided. *Cross-sectional* - **Cross-sectional studies** assess exposure and outcome simultaneously, making it difficult to establish temporal relationship or causation. - They are suitable for estimating prevalence but not for investigating etiology of diseases with long latency periods like cancer. *Case-series* - A **case series** describes characteristics of a group of patients with a particular disease, but lacks a comparison group. - It cannot establish an association between exposure and outcome, as there is no control for confounding factors. *Single-arm interventional* - A **single-arm interventional study** involves administering an intervention to a single group and observing the outcome, primarily for evaluating efficacy or safety of new treatments. - It is not designed to investigate associations between environmental exposures (like mobile phone radiation) and disease, as it lacks a control group and focuses on interventions rather than observational epidemiology.
Question 14: The villages A and B have the following age compositions: Which of the following is the best indicator for comparing the death rates of these two villages?
- A. Crude death rate
- B. Specific death rate
- C. Proportional mortality rate
- D. Age standardized death rate (Correct Answer)
Explanation: ***Age standardized death rate*** - This method adjusts for differences in the **age structures** of the two populations, providing a more accurate comparison of underlying mortality risks. - Since the question clearly shows significant differences in the age compositions of Village A and Village B, age standardization is essential to avoid misleading conclusions drawn from crude rates. *Crude death rate* - The crude death rate is the total number of deaths in a period divided by the total population, which **does not account for age differences**. - Comparing crude death rates between populations with different age structures can be misleading because older populations naturally have higher death rates. *Specific death rate* - Specific death rates refer to death rates for particular **age groups, causes, or other characteristics**. - While useful for detailed analysis, it doesn't provide a single, summary measure for comparing the overall mortality burden between two populations with differing age structures. *Proportional mortality rate* - This rate indicates the **proportion of deaths due to a specific cause** out of all deaths. - It does not measure the risk of dying in a population and is not suitable for comparing overall mortality burden between two communities, especially when age structures vary significantly.
Question 15: Which of the following is/are suggested by rising incidence rates of any disease? 1. Need for a new disease control programme 2. Improvement in reporting practices 3. Change in the etiology of the disease Select the correct answer using the codes given below:
- A. 2 and 3 only
- B. 1, 2 and 3 (Correct Answer)
- C. 1 and 3 only
- D. 1 only
Explanation: ***1, 2 and 3*** - **Rising incidence rates** can suggest multiple scenarios in epidemiology: **Statement 1 - Need for a new disease control programme**: A true increase in incidence indicates rising disease burden, which may necessitate public health intervention through disease control programs, surveillance strengthening, or prevention strategies. **Statement 2 - Improvement in reporting practices**: Enhanced surveillance systems, better diagnostic capabilities, increased healthcare access, or improved physician awareness can lead to more cases being detected and reported. This creates an *apparent* rise in incidence without a true increase in disease occurrence (surveillance artifact). **Statement 3 - Change in the etiology of the disease**: While etiology (causation) itself typically doesn't change, this statement refers to changes in **risk factors, exposure patterns, environmental conditions, or pathogen characteristics** (such as emergence of more virulent strains, antimicrobial resistance, or vector behavior changes) that can genuinely increase disease incidence. All three statements represent valid interpretations of rising incidence rates in epidemiological practice. *2 and 3 only* - This incorrectly excludes the public health implication that rising incidence may warrant new disease control programs, which is a fundamental principle of public health response. *1 and 3 only* - This overlooks the critical role of **surveillance artifacts** where improved reporting practices can increase observed incidence without true disease increase—a common phenomenon in epidemiology. *1 only* - This is too restrictive, failing to recognize that rising incidence can result from multiple factors including improved detection systems and genuine changes in disease transmission dynamics or risk factor exposure.
Question 16: What constitutes the denominator in ‘Total Dependency Ratio’?
- A. Mid year population
- B. Population 15–45 years of age
- C. Population 15–64 years of age (Correct Answer)
- D. Population less than 14 and more than 65 years of age
Explanation: ***Population 15–64 years of age*** - The **total dependency ratio** is calculated by dividing the sum of the dependent population (ages 0-14 and 65+) by the **working-age population** (15-64 years). - This age group traditionally represents the population that is generally considered to be economically productive and supporting the dependent populations. *Mid year population* - The **mid-year population** is the total population count at the midpoint of a year, used as the denominator for many public health rates, but not specifically for the dependency ratio. - While it's the base for many demographic calculations, it does not specifically represent the **working-age group** for dependency calculations. *Population 15–45 years of age* - This age range defines a **subset of the working-age population** but is too narrow, as it excludes economically productive individuals between 46 and 64 years old. - Using this range would artificially **inflate the dependency ratio** by undercounting the contributing working population. *Population less than 14 and more than 65 years of age* - This age group represents the **dependent population** (young children and retirees) and forms the numerator of the total dependency ratio. - Including them in the denominator would be incorrect as they are the very groups whose **reliance on the working-age population** is being measured.
Question 17: By which one of the following studies can relative risk be best calculated?
- A. Correlation study
- B. Case-control study
- C. Randomised control trial
- D. Cohort study (Correct Answer)
Explanation: ***Cohort study*** - A cohort study directly follows groups of individuals (cohorts) over time to observe the **incidence of disease** in exposed versus unexposed groups. - This design allows for the direct calculation of **absolute risks** in each group, from which the **relative risk** can be easily derived. *Correlation study* - A correlation study examines the **relationship between variables** in a population, often using aggregated data, but does not follow individuals over time to assess incidence. - It can identify associations between exposures and outcomes but cannot calculate relative risk directly because it does not provide individual risk data. *Case-control study* - A case-control study compares individuals with a disease (cases) to individuals without the disease (controls) and looks back in time to determine past exposures. - While it can estimate the **odds ratio**, which approximates relative risk when the disease is rare, it cannot directly calculate relative risk because it does not provide the incidence of the disease in exposed versus unexposed populations. *Randomised control trial* - A randomized controlled trial (RCT) is an experimental study where participants are randomly assigned to an intervention or control group to assess the efficacy of an intervention. - While RCTs can calculate relative risk, they are primarily designed to establish **causality** and intervention effectiveness, not to investigate risk factors in naturally occurring populations in the same way a cohort study does for epidemiological insight.
Question 18: Orthotolidine (OT) test is done for determining residual free chlorine quantitatively and qualitatively. What is the colour of the solution after adding OT which indicates presence of free chlorine?
- A. Blue
- B. Green
- C. Yellow (Correct Answer)
- D. Red
Explanation: ***Yellow*** - The **Orthotolidine (OT) test** historically was used to detect and quantify residual **free chlorine** in water. - When Orthotolidine reagent is added to water containing free chlorine, it produces a **yellow color**, with the intensity of the yellow directly proportional to the amount of free chlorine present. - **Important Note:** The OT test has been **discontinued and is no longer recommended** due to orthotolidine being a **suspected carcinogen**. It has been replaced by safer methods like the **DPD (N,N-diethyl-p-phenylenediamine) test**, which also detects free chlorine but uses a safer reagent. *Blue* - A blue color is not associated with the Orthotolidine test for free chlorine. - Other water quality tests or reagents might yield a blue color for different parameters. *Green* - A green color does not indicate the presence of free chlorine in the Orthotolidine test. - It may suggest interference from other substances or mixed reactions. *Red* - A red color is not the characteristic indicator for free chlorine in the Orthotolidine test. - Red or pink colors are associated with the **DPD method** (the current standard test), which produces a pink/red color in the presence of free chlorine.
Question 19: Consider the following in respect of Navjyot Shishu Suraksha Karyakram (NSSK): 1. It is a programme aimed to train health personnel in basic newborn care and resuscitation 2. It addresses care at birth issues (i.e. prevention of hypothermia, prevention of infection, early initiation of breastfeeding and basic newborn resuscitation) 3. The objective is to have a trained health person in basic newborn care and resuscitation at every delivery point Which of the statements given above are correct?
- A. 1, 2 and 3 (Correct Answer)
- B. 1 and 2 only
- C. 2 and 3 only
- D. 1 and 3 only
Explanation: ***1, 2 and 3*** - The **Navjyot Shishu Suraksha Karyakram (NSSK)** focuses on training healthcare personnel in **basic newborn care and resuscitation** to reduce neonatal mortality. - It addresses critical **care at birth issues**, including preventing **hypothermia**, preventing **infections**, promoting **early breastfeeding initiation**, and providing **basic newborn resuscitation**. The overarching objective is to ensure that a trained health person is available at **every delivery point** to provide essential newborn care. *1 and 2 only* - This option incorrectly excludes the third statement regarding the objective of having a trained health person at every delivery point. - The target of ensuring trained personnel at every birth is a core component and objective of the NSSK. *2 and 3 only* - This option incorrectly excludes the first statement, which details the primary function of training health personnel. - The NSSK is fundamentally a training program designed to equip healthcare providers with the necessary skills. *1 and 3 only* - This option incorrectly excludes the second statement, which outlines the specific care at birth issues addressed by the program. - The identified issues such as preventing hypothermia, infection, and promoting breastfeeding are central to the effectiveness of the NSSK.
Question 20: The most important indicator for assessment of impact in Salt Iodization Programme is:
- A. Testing median urinary iodine excretion (Correct Answer)
- B. Testing Iodine content of salt at consumer level
- C. Testing iodine content of salt at production level
- D. Testing serum iodine levels
Explanation: ***Testing median urinary iodine excretion*** - **Urinary iodine excretion** is the most reliable biochemical indicator of recent **iodine intake** and is considered the best measure for assessing the iodine status of a population. - The **median urinary iodine concentration** is used to categorize a population's iodine nutrition status as deficient, adequate, or in excess, providing a direct measure of programme impact. *Testing iodine content of salt at consumer level* - While important for monitoring **salt iodization efforts**, this only reflects the availability of iodized salt, not necessarily the actual **iodine intake** or nutritional status of the consumers. - Salt content can degrade over time due to improper storage, heat, and humidity, leading to discrepancies between the salt's iodine content and the iodine actually consumed. *Testing iodine content of salt at production level* - This is crucial for **quality control** and ensuring compliance with iodization standards at the source. - However, it does not account for potential **iodine loss** during transport, storage, and household use, nor does it directly reflect the population's actual iodine status. *Testing serum iodine levels* - **Serum iodine levels** are primarily regulated by the thyroid gland and are not a sensitive indicator of a population's *recent iodine intake* or overall iodine nutrition status. - These levels are often maintained within a narrow range even with varying intake, making them less useful for monitoring large-scale intervention programmes like **salt iodization**.