Variation in hospital caesarean section rates for women with at least one previous caesarean section: a population based cohort study

Abstract

Background: Internationally, repeat caesarean sections (Robson Classification Group 5) make the single largest contribution to overall caesarean section rates and hospital-to-hospital variation has been reported. It is unknown if case-mix and hospital factors explain variation in hospital rates of repeat caesarean sections and whether these rates are associated with maternal and neonatal morbidity. Methods: This population-based record linkage study utilised data from New South Wales, Australia between 2007 and 2011. The study population included all maternities with prior caesarean section that were singleton, cephalic and at term. Multilevel regression models were used with primary outcomes of ‘planned repeat caesarean section’ and ‘intra-partum caesarean section’. The associations between quintiles of risk-adjusted hospital rates of planned and intra-partum repeat caesarean sections and case-mix adjusted maternal and neonatal morbidity rates, postpartum haemorrhage rates and Apgar score below 7 at five minutes rates were also assessed. Results: Of 61894 maternities with a prior caesarean section in 81 hospitals, 82.1% resulted in a repeat caesarean section and 17.9% in vaginal birth. Of the caesarean sections, 72.7% were planned and 9.4% were unplanned intra-partum. Crude hospital rates of planned caesarean sections ranged from 50.7% to 98.4%. Overall 49.0% of between-hospital variation in planned repeat caesarean section rates was explained by patient characteristics (17.3%) and hospital factors (31.7%). Increased odds of planned caesarean section were associated with private hospital status and lower hospital propensity for vaginal birth after caesarean. There were no associations between quintiles of planned repeat caesarean section and adjusted morbidity rates. Crude rates of intra-partum caesarean section ranged from 12.9% to 71.9%. In total, 27.5% of between hospital variation in rates of intra-partum caesarean section was explained by patient (19.5%) and hospital factors (8.0%). The adjusted morbidity rates differed among quintiles of hospital intra-partum caesarean section rates, but were influenced by a few hospitals with outlying rates. 3 Conclusions: About half of the variation in hospital planned repeat caesarean section rates was explained and strategies aimed at modifying these rates should not affect morbidity rates. Intra-partum caesarean sections were associated with morbidity but not in a systematic manner