Impact of risk-adjusting cesarean delivery rates when reporting hospital performance

Context.-Hospitals and health plans are often ranked on rates of cesarean delivery, under the assumption that lower rates reflect more appropriate, more efficient care. However, most rankings do not account for patient factors that affect the likelihood of cesarean delivery. Objective.-To compare hospital cesarean delivery rates before and after adjusting for clinical risk factors that increase the likelihood of cesarean delivery. Design.-Retrospective cohort study, Setting.-Twenty-one hospitals in northeast Ohio. Patients.-A total of 26 127 women without prior cesarean deliveries admitted for labor and delivery from January 1993 through June 1995. Main Outcome Measures.-Hospital rankings based on observed and risk-adjusted cesarean delivery rates. Results.-The overall cesarean delivery rate was 15.9% and varied (P<.001) from 6.3% to 26.5% in individual hospitals. Adjusted rates varied from 8.4% to 22.0%. The correlation between unadjusted and adjusted hospital rankings (ie, 1-21) was only modest (R=0.35, P=.12). Whereas 7 hospitals were classified as outliers tie, had rates higher or lower [P<.05] than overall rate) on the basis of both unadjusted and adjusted rates, outlier status changed for 5 hospitals (24%), including 2 that changed from outliers to nonoutliers, 2 that changed from nonoutliers to outliers, and 1 that changed from a high outlier to a low outlier. Conclusions.-Cesarean delivery rates varied across hospitals in a single metropolitan region. However, rankings that fail to account for clinical factors that increase the risk of cesarean delivery may be methodologically biased and misleading to the public.