Clinical case mix adjustment of cesarean delivery rates in U.S. military hospitals, 2002.
OBJECTIVE
To assess whether significant variations in observed cesarean rates in U.S. military hospitals may be attributed to differences in clinical case mix.


METHODS
Hospital discharge records for births in U.S. military hospitals in 2002 were grouped into mutually exclusive clinical strata to calculate predicted cesarean rates for subgroups defined by maternal race, health plan, hospital location, delivery volume, teaching status, and neonatal intensive care unit (NICU) status. The 95% confidence interval (CI) around each standardized ratio (SR) of the observed-to-predicted cesarean rate was used to assess statistical significance.


RESULTS
Observed cesarean rates were significantly higher than predicted rates for small hospitals (23.1% and 20.4%, respectively, SR 1.13, 95% CI 1.08-1.19), teaching hospitals (23.7% and 22.5%, respectively, SR 1.05, 95% CI 1.02-1.08), black women (25.1% and 22.8%, respectively, SR 1.10, 95% CI 1.05-1.14), and other minorities (22.7%, and 21.6%, respectively, SR 1.05, 95% CI 1.01-1.09). No significant differences between observed and predicted cesarean rates were found across hospital locations or NICU status. Significant differences found for non-managed care beneficiaries were attributed to teaching status of the hospitals in which they delivered.


CONCLUSIONS
Clinical case mix does not adequately account for the relatively high rates of cesarean delivery observed for small hospitals and teaching hospitals and among black women in the study population. Further study is recommended to identify additional clinical and nonclinical factors that should be considered when comparing performance across institutions, health plans, or individual providers.
Linton
Andrea
A
Center for Health Care Management Studies, Office of the Assistant Secretary of Defense, Health Affairs, TRICARE Management Activity, Falls Church, Virginia 22041-3206, USA.
Peterson
Michael R
MR
Williams
Thomas V
TV
D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data*; D036861:Delivery, Obstetric / Q000706:statistics & numerical data; D005260:Female; D006276:Health Facility Size; D006772:Hospitals, Military / Q000706:statistics & numerical data*; D006784:Hospitals, Teaching / Q000706:statistics & numerical data; D006801:Humans; D007363:Intensive Care Units, Neonatal; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D020379:Risk Adjustment; D014481:United States