A study conducted among 300 people 100 who are affected by lung cancer and 200 who are smokers not affected by lung cancer, what type of study design is represented here?

Appeared in: NORCET 3 - 2022 (Shift-2)

Explanation

The study starts by identifying two distinct groups: one with the disease (100 people with lung cancer - the 'cases') and one without the disease (200 people without lung cancer - the 'controls').
This design is known as a case-control study, which is fundamentally retrospective.
It proceeds 'backward' from the effect (disease) to the potential cause (exposure).
The goal is to compare the past exposure to a risk factor (e.g., smoking) between the cases and controls to determine if there is an association.

Why Other Options Were Wrong

Option A: A cohort study starts with an exposure (e.g., a group of smokers and a group of non-smokers) and follows them forward in time to see who develops the disease. The question describes starting with the disease, not the exposure.
Option B: A field trial is an experimental/interventional study, not an observational one. It involves applying a preventive measure to healthy individuals in the community to see if it prevents disease.
Option D: A cross-sectional study measures both exposure and disease at a single point in time (a 'snapshot'). It doesn't specifically select groups based on their disease status beforehand.

Related Visual

A flowchart illustrating the difference between case-control and cohort studies. The case-control branch starts with Disease and No Disease and points backward to Exposure...

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of epidemiological study designs as background academic context rather than a clinical decision trigger.
Understanding study designs is crucial for nurses to critically appraise research evidence and apply it to practice (Evidence-Based Practice).
A nurse reading a case-control study on a new risk factor for a hospital-acquired infection would understand its limitations (e.g., recall bias) and strengths (e.g., speed).
What if? If the study had selected 100 smokers and 200 non-smokers and then followed them for 10 years to record who developed lung cancer, the design would change from a case-control to a prospective cohort study.

How to Approach the Question

First, identify the core components of the study described in the question.
Ask: What is the starting point of the study? Is it the disease (outcome) or the exposure (risk factor)?
In this case, the study starts by identifying people with lung cancer (the disease/outcome). This is the key characteristic of a case-control study.
Next, determine the direction of inquiry. Is it looking forward in time (prospective) or backward (retrospective)? Since it starts with the disease, it must look backward to find the cause.
Compare this structure to the definitions of the options. A cohort study starts with exposure and looks forward. A cross-sectional study is a snapshot. A field trial is an intervention. Only the case-control design matches the description.

Concept Tested & Keywords

Concept Tested: Identification of epidemiological study designs
Stem keywords: study design, lung cancer, smokers, affected, not affected
Lead-in keywords: what type
Negative lead-in flag: false

Question ID

Q7OEcr_nK-dmw3acvix_MZ

Reference Book

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 64-66

E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) p. 2846-2848

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