Question

Many children from a particular community coming to a hospital were detected to have acute lymphoblastic leukemia (ALL). It was assumed that it is due to the presence of cytotoxic waste in the water of that community. If a case-control study has to be done to find whether the chemical and ALL are associated, what will be taken as the control?

• A. Children from the area exposed, but unaffected with the disease
• B. Children from the area not exposed and affected with the disease
• C. Children coming to your OPD, who do not have the disease
• D. All children with ALL irrespective of exposure status

Answer 1

The Correct Option is D

In a case-control study aimed at determining the association between cytotoxic waste exposure and acute lymphoblastic leukemia (ALL), the selection of controls is crucial. The correct control group should represent the population at risk that shares similar characteristics with the cases but do not have the disease. Here, the goal is to understand whether the presence of cytotoxic chemicals is associated with the occurrence of ALL. So, selecting the appropriate control group involves:

• Understanding the Study Objectives: The study aims to explore the relationship between an environmental exposure (cytotoxic waste) and a disease outcome (ALL).
• Selecting Controls: Controls should ideally have the same risk of being exposed to cytotoxic waste, without having developed ALL, to compare the exposure levels effectively.
• Review of Options: Let's evaluate the provided options for control groups:

Option	Evaluation
Children from the area exposed, but unaffected with the disease	These children represent the exposed group without the disease, suitable for exploring exposure-disease relation.
Children from the area not exposed and affected with the disease	This group has disease but not exposure, inappropriate as controls.
Children coming to your OPD, who do not have the disease	Controlled group from broader population without targeted exposure context.
All children with ALL irrespective of exposure status	Controls should not have the disease; this option is incorrect for a control group.

Thus, the most suitable control group is Children from the area exposed, but unaffected with the disease. This allows us to compare the exposed without disease against exposed with ALL to determine association.