Effect of severity of illness on cesarean delivery rates in Washington State

Admission severity-of-illness score is strongly associated with the primary term singleton vertex cesarean delivery rate among hospitals in Washington State. Approximately 50% of variation in hospital primary term singleton vertex cesarean delivery rates appeared to be related to admission severity of illness. This relationship persisted over time despite a statewide decrease in cesarean delivery, suggesting that patient acuity will likely continue to contribute to hospital variation in cesarean delivery rates despite perinatal quality improvement efforts. The major implication of this study is that patient acuity should be considered when determining optimal cesarean delivery rates. High-acuity hospitals are likely to have high cesarean rates because they provide a specific role in serving regional needs. To hold these centers to an arbitrary benchmark may jeopardize the funding necessary to support regional safety net institutions.