Association between rising professional liability insurance premiums and primary cesarean delivery rates.

OBJECTIVE: To estimate the association between changes in Illinois professional liability premiums for obstetrician-gynecologists and singleton primary cesarean delivery rates.
METHODS: Data from the National Center for Health Statistics were used to identify all singleton births between 37 weeks and 44 weeks of gestation occurring in Illinois from 1998 through 2003. Primary cesarean delivery rates for women delivered between 37 weeks and 44 weeks of gestation per 1,000 gravid women eligible to have a primary cesarean delivery were calculated for each Illinois county. The annual medical professional liability premium for each county in Illinois was represented by the reported professional liability insurance rate charges (adjusted to 2004 dollars) from the ISMIE Mutual Insurance Company. Separate analyses were conducted for nulliparous and multiparous women. The independent association between county-level primary cesarean delivery rates and the previous year's insurance premiums was evaluated using linear regression models.
RESULTS: During the study period, 817,521 women were eligible for inclusion in the analysis. The county-level mean primary cesarean delivery rate increased from 126 to 163 per 1,000 (P<.001) eligible women, whereas the mean annual medical professional liability insurance premiums also rose significantly (from $60,766 in 1997 to $83,167 in 2002, P<.001). Multivariable analyses demonstrated that for each annual $10,000 insurance premium increase, the primary cesarean delivery rate increased by 15.7 per 1,000 for nulliparous women. This association also was evident for multiparous women, who had an increase in cesarean deliveries of 4.7 per 1,000 for every $10,000 increase.
CONCLUSION: Higher rates of primary cesarean delivery are associated with increased medical professional liability premiums for obstetrician-gynecologists in Illinois. LEVEL OF EVIDENCE: II.