Bailit J L, Dooley S L, Peaceman A N
Department of Obstetrics and Gynecology, Northwestern University Medical School, Chicago, Illinois, USA.
Obstet Gynecol. 1999 Jun;93(6):1025-30. doi: 10.1016/s0029-7844(98)00536-5.
To create a method of controlling for case mix so that inferences could be made about variation in cesarean rates among hospitals.
A total of 160,753 births from 1991 Illinois birth certificate data were analyzed. A multivariate model of characteristics independently associated with cesarean delivery was developed from a random 25% sample, validated on the other 75%, and used to create a probability of cesarean delivery for each woman. The validated model was used to calculate a predicted primary cesarean delivery rate for the 154 hospitals in Illinois that did at least 100 deliveries per year.
The final model included both medical and sociodemographic risk factors and predicted primary cesarean rates accurately over a full range of rates. Thirty-five hospitals (23%) had actual rates that were higher than their individual predicted 95% confidence interval (CI). Eighty-nine hospitals (58%) had actual rates within predicted CIs. Thirty hospitals (20%) had actual rates that were lower than the predicted 95% CI. Twenty-three percent of hospitals with actual rates greater than predicted rates were not in the top quartile of actual rates. Twenty-seven percent of hospitals with actual rates in the top quartile were doing cesarean deliveries appropriate for the risk status of the population served.
Risk adjusting for hospital case mix more accurately identifies outlier hospitals than raw, unadjusted primary cesarean delivery rates. We believe that risk adjusting should be the first step in understanding variations in primary cesarean delivery rates.
创建一种病例组合控制方法，以便能够推断医院剖宫产率的差异。
分析了1991年伊利诺伊州出生证明数据中的160753例分娩。从随机抽取的25%样本中建立了与剖宫产独立相关特征的多变量模型，在另外75%的样本上进行验证，并用于计算每位女性的剖宫产概率。使用经过验证的模型计算伊利诺伊州每年至少进行100例分娩的154家医院的预测首次剖宫产率。
最终模型包括医学和社会人口统计学风险因素，并在整个剖宫产率范围内准确预测首次剖宫产率。35家医院（23%）的实际剖宫产率高于其各自预测的95%置信区间（CI）。89家医院（58%）的实际剖宫产率在预测的CI范围内。30家医院（20%）的实际剖宫产率低于预测的95%CI。实际剖宫产率高于预测率的医院中，23%不在实际剖宫产率最高的四分位数中。实际剖宫产率处于最高四分位数的医院中，27%进行的剖宫产手术与所服务人群的风险状况相符。
对医院病例组合进行风险调整比原始的、未经调整的首次剖宫产率更能准确识别出异常医院。我们认为，风险调整应是理解首次剖宫产率差异的第一步。
