Hospital quality rankings do not always adjust for reliability

Many hospital quality-of-care rankings so not account for “statistical noise” when it comes to measuring mortality for vascular surgery, according to a study in the Journal of Vascular Surgery.   

For the study, researchers analyzed data for patients who underwent one of five common vascular procedures, including open and endovascular abdominal aortic aneurysm repair, carotid endarterectomy, lower extremity bypass, and aorto-femoral bypass.  The researchers examined the 30 day mortality rates for these patients, and then adjusted these estimates for statistical noise using a technique known as reliability adjustment. 

The results showed that adjustment for reliability had a dramatic effect on hospital rankings. Overall, 43% of hospitals were reclassified into either a higher or lower quartile of performance using traditional methods of risk-adjustment.   

The researchers recommend that reliability adjustment should be standard for comparing hospital quality for vascular procedures. 

(Sources: Journal of Vascular Surgery,, January, 2011; The Advisory Board Daily Briefing,, January 11, 2011)