Do group practices have lower caesarean rates than solo practice obstetric clinics? Evidence from Taiwan

Objective: This study examined physicians' propensity for caesarean deliveries at solo versus group practice obstetrics/gynaecology (ob/gyn) clinics in Taiwan. Method: We used population-based (National Health Insurance) claims data covering all 253 618 singleton deliveries conducted at ob/gyn clinics, during 2000-02. The dependent variable, delivery mode, was treated as dichotomous [caesarean section (CS) = 1, vaginal delivery (VD) = 0]. The independent variable of interest was practice size, classified into four categories: 1, 2, 3 and 4+ physicians. Multilevel logistic regression modelling, accounting for clinic-level variation in CS rates, was used to examine CS likelihood by practice size, among the total delivery sample and among the sub-samples disaggregated by obstetric complication status. Results: Solo practices have 7% excess caesarean cases relative to large group practices. After controlling for patient's age, physician demographics, the clinic's geographic location and size of delivery service, and clinic-level random effect, solo practice physicians were 5.38 times as likely as 4+ physician practices to provide caesarean delivery (CI = 4.18 ∼ 6.93), 2-physician practices were 3.87 times (CI = 2.99 ∼ 5.01) and 3-physician practices 2.72 times (CI = 2.06 ∼ 3.59) as likely as 4+ physician practices to provide caesarean delivery. This effect is driven by higher CS propensity among solo and small groups among cases with obstetrically less salient complications and the 'no complications' subset of patients. Wide confidence intervals for odds ratios in these sub-samples also attest to wide variations in clinic-level CS rates among these patient groups. Conclusions: Solo physicians are the most likely to provide caesarean delivery, and CS likelihood decreases with increasing number of physicians in the practice. Group practice support may reduce the CS likelihood, when it is not clinically indicated. Policy makers should consider initiatives to limit full service delivery privileges to group practice obstetric clinics, in order to reduce unnecessary CS. Solo practice clinics should, at best, be licensed as birthing centres, required to transfer patients needing CS to a larger facility.