Estimation of an expected caesarean section rate taking into account the case mix of a maternity hospital. Analysis from the AUDIPOG Sentinelle Network (France)

Objective To provide maternity unit with an expected caesarean section rate , according to its case mix (i.e. women's characteristics associated with c aesarean section risk). Design Cohort study. Setting 149 maternity units in France. Sample 40,512 single births collected by the French Sentinelle Network, in January every year, from 1994 until 1998. Methods Univariate analysis was used to identify caesarean section risk fac tors, and multivariate analysis to adjust for the role of the maternity uni ts' characteristics, after taking into account the women's characteristics. A two-level logistic model was used to show that the caesarean section rat e varied according to maternity units' characteristics and to estimate ther efore expected caesarean section rates (before and during labour), for each maternity unit, according to its case mix. Main outcome caesarean section rates (before and during labour). Results Within the Sentinelle Network the caesarean section rate was 15.0% (7.6% were before labour). The joint effect of the size and juridical statu s on caesarean section risk was studied. The reference hospital was univers ity maternity units with more than 2000 deliveries/year. Community or priva te maternity units with more than 2000 deliveries/year carried out fewer pr ophylactic caesarean sections than the reference hospital (ORadj = 0.7 and 0.6, respectively). Conversely, private maternity units with fewer than 200 0 deliveries/year performed more prophylactic caesarean sections than the r eference hospital (ORadj = 1.7). The two-level logistic model showed that a maternity unit effect still existed after taking into consideration both w omen's characteristics and those of the maternity unit, and estimated expec ted caesarean section rates. Conclusion Knowledge of the expected caesarean section rate constitutes a p ersonal reference to which the maternity hospital can compare its observed caesarean section rate, and is thus likely to have a significant effect on delivery practices.