Simpson's paradox: how performance measurement can fail even with perfect risk adjustment

Efforts to measure quality using patient outcomes—whether hospital mortality rates or major complication rates for individual surgery—often become mired in debates over the adequacy of adjustment for case-mix. Some hospitals take care of sicker patients than other hospitals. Some surgeons operate on patients whom other surgeons feel exceed their skill levels. We do not want to penalise hospitals or doctors who accept referrals for more complex patients. Yet, we also do not want to miss opportunities for improvement. Maybe a particular hospital that cares for sicker patients achieves worse outcomes than other hospitals with similar patient populations. This debate over the adequacy of case-mix adjustment dates back to Florence Nightingale's publication of league tables for mortality in 19th century English hospitals.1 We have made some progress. Some successes have involved supplementing the diagnostic codes and demographic information available in administrative data with a few key clinical variables.

Source: Quality and Safety in Health Care - August 12, 2014 Category: Health Management Authors: Marang-van de Mheen, P. J., Shojania, K. G. Tags: Editorials Source Type: research