Question

Research is being conducted to find the association between aniline dye exposure and bladder cancer in workers who have worked in the industry for > 20 years. Two groups were formed: one directly involved with dye handling and the other group consisting of office clerks not directly exposed to the dye. Years of occupation were noted from records. What type of study is being performed?

• A. Retrospective cohort study
• B. Prospective cohort study
• C. Case-control study
• D. Intervention and response

Answer 1

The Correct Option is A

The study described involves examining the relationship between aniline dye exposure and bladder cancer in workers who have been in the industry for more than 20 years, where data such as years of occupation are sourced from existing records. This suggests the study is observational in nature, focusing on the past exposure and its potential impact on health outcomes.

The types of epidemiological studies commonly discussed include:

• Retrospective cohort study: In this study, participants are selected based on past exposure and are followed in the present to study the outcome. It collects historical data, then looks forward from this point to see the effect of an exposure.
• Prospective cohort study: This involves selecting subjects in the present and following them into the future to examine the outcome. It starts with an exposure and follows to see if it develops into a particular outcome.
• Case-control study: Here, cases (with the outcome) and controls (without the outcome) are selected, and researchers look back retrospectively to determine exposure status.
• Intervention and response study: This type is experimental where participants are assigned to different interventions to directly measure response.

Given that the study is about reviewing past records to assess exposure and its relation to outcomes, it fits the framework of a Retrospective cohort study because:

• Participants are grouped based on past exposures (those who handled dye vs. clerks).
• Outcome (bladder cancer) is assessed in relation to these historical exposures.