A study reports a statistically significant association (p=0.03) between coffee consumption and pancreatic cancer. However, coffee drinkers also smoke more heavily, and smoking is a known risk factor for pancreatic cancer. The bias operating here is:
- A Information bias
- B Confounding ✓
- C Selection bias
- D Lead-time bias
Correct answer: B. Confounding
Explanation
Confounding occurs when a third variable (smoking) is associated with both the exposure (coffee) and the outcome (pancreatic cancer) and distorts the true relationship. A confounder must be associated with the exposure, be an independent risk factor for the disease, and not be on the causal pathway. Information bias involves errors in measurement, while selection bias involves non-representative sampling.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.