Patient Safety & Quality Improvement USMLE Step 1 Practice Question
A hospital implements daily 30-minute safety huddles in its ICU and tracks patient outcomes over 6 months. During analysis of mortality data, the team notes that sicker patients (higher APACHE II scores >25) are admitted more frequently during winter months, with higher baseline sepsis rates (40% vs 15% in summer). Fewer medication errors occur post-intervention, but seasonal admission acuity varies significantly. What is this variable called, and why must it be controlled for valid outcome assessment?
Answer choices
- AA confounder; it may explain observed outcome differences independent of the huddle interventionCorrect answer
- BA placebo effect; it artificially improves patient satisfaction
- CA covariate; it should be eliminated from the analysis entirely
- DA selection bias; it affects only the initial patient enrollment
- EA bias; it proves the huddle had no real effect on outcomes
- FAn interaction variable; it measures the combined effect of season and medication error rates on mortality
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