During a journal club, medical residents evaluate several recently published epidemiological studies. Each study contains a potential methodological vulnerability. Match each specific study scenario to the epidemiological term that best describes the dominant bias or flaw.
- A 5-year trial of a demanding behavioral weight-loss intervention reports significant BMI reduction, but 45% of the intervention group dropped out due to time constraints and were excluded from the final analysis.Attrition bias
- A case-control study shows that parents of children recently diagnosed with autism spectrum disorder are much more likely to intensely search their memory and report minor illnesses during early childhood compared to parents of healthy children.Recall bias
- A study on ward handwashing practices demonstrates a sharp, temporary increase in compliance rates while researchers are conspicuously present on the floor observing the nursing staff.Hawthorne effect
- An observational database review concludes that a novel biologic agent is associated with higher mortality than standard therapy; however, the novel agent is typically prescribed only to patients with refractory, severe disease.Confounding by indication
Answer
The dietary trial dropout matches with attrition bias, the parents' memory of illness matches with recall bias, the altered handwashing behavior matches with the Hawthorne effect, and the prescribing patterns based on disease severity match with confounding by indication.
Each scenario accurately depicts a classic epidemiological vulnerability. Attrition bias occurs through differential loss to follow-up; recall bias occurs through differential memory of past exposures; the Hawthorne effect occurs through subject awareness of observation; and confounding by indication occurs when treatment allocation is driven by baseline disease severity.
Step-by-Step Solution
Key Concept
Identification of specific biases and confounders in clinical research design.
Estimated Time:1m 30s