Whitsel A I, Capeless E C, Abel D E, Stuart G S
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Vermont College of Medicine, Burlington, USA.
Am J Obstet Gynecol. 2000 Nov;183(5):1170-5. doi: 10.1067/mob.2000.108849.
Our objective was to determine whether case mix model adjustment would help to explain differences in cesarean delivery rates between community and university hospitals. We also wished to define a patient population in which the cesarean delivery rate would be more reflective of individual practice patterns than of obstetric or medical risk.
Established risk factors for cesarean delivery were identified by retrospective chart review at two community hospitals (designated A and B) and a university hospital. Each delivery was assigned exclusively to 1 of 6 risk categories: (1) multiple gestation, (2) fetal malpresentation, (3) delivery at <36 weeks' gestation, (4) not suitable for trial of labor, and (5) term delivery (> or =36 weeks' gestation) with medical complications, and (6) term delivery (> or =36 weeks' gestation) without medical complications. Parity and history of cesarean delivery further subdivided these categories into a total of 18 unique subgroups. Case mix was defined as the distribution of patients into each subgroup. Patients assigned to the categories of multiple gestation, fetal malpresentation, delivery at <36 weeks' gestation, and not eligible for trial of labor were considered to compose the group at high risk for cesarean delivery. The remaining patients composed the group at low risk for cesarean delivery. Observed cesarean delivery rates were calculated for each cell of the case mix grid within individual hospitals. Total, primary, and repeat cesarean delivery rates were determined for each hospital. The cesarean delivery rates for the low-risk populations were calculated. Data were evaluated both by chi(2) test and by direct standardization analysis with the university hospital case mix used as the standard population.
A total of 5705 delivery reports were reviewed (university hospital, n = 4538; hospital A, n = 531; hospital B, n = 636). The cesarean delivery rates were significantly different between hospitals (university hospital, 16. 9%; hospital A, 13.6%; hospital B, 12.0%; P =.002). The distributions of patients in the high-risk group were also significantly different between hospitals (university hospital, 16. 8%; hospital A, 5.8%; hospital B, 8.8%; P = .001). The percentage of medically complicated cases in the low risk for cesarean group was significantly higher at the university hospital (university hospital, 16.9%; hospital A, 8.8%; hospital B, 9.8%; P =.001). However, no statistical differences were detected between hospitals in either the observed cesarean delivery rates or the standardized rates for the low-risk groups.
The case mix model provides a more accurate method of comparing cesarean delivery rates between community and university hospitals. The low-risk group of patients discriminated in this model represents a population in which the cesarean delivery rate may be more reflective of individual practice patterns than of maternal or fetal risks.
我们的目的是确定病例组合模型调整是否有助于解释社区医院和大学医院剖宫产率的差异。我们还希望定义一个患者群体，在该群体中剖宫产率更能反映个体医疗实践模式，而非产科或医疗风险。
通过对两家社区医院（分别指定为A和B）以及一家大学医院的病历进行回顾性分析，确定已有的剖宫产风险因素。每次分娩仅被归入6个风险类别中的1个：（1）多胎妊娠；（2）胎位异常；（3）孕周<36周分娩；（4）不适合试产；（5）足月分娩（孕周≥36周）合并医疗并发症；（6）足月分娩（孕周≥36周）无医疗并发症。产次和剖宫产史进一步将这些类别细分为总共18个独特的亚组。病例组合定义为患者在每个亚组中的分布情况。被归入多胎妊娠、胎位异常、孕周<36周分娩以及不适合试产类别的患者被视为剖宫产高风险组。其余患者构成剖宫产低风险组。计算各医院病例组合网格中每个单元格的观察到的剖宫产率。确定每家医院的总剖宫产率、初次剖宫产率和再次剖宫产率。计算低风险人群的剖宫产率。数据通过卡方检验以及以大学医院病例组合作为标准人群的直接标准化分析进行评估。
共审查了5705份分娩报告（大学医院，n = 4538；医院A，n = 531；医院B，n = 636）。各医院之间的剖宫产率存在显著差异（大学医院，16.9%；医院A，13.6%；医院B，12.0%；P = 0.002）。高风险组患者在各医院之间的分布也存在显著差异（大学医院，16.8%；医院A，5.8%；医院B，8.8%；P = 0.001）。大学医院剖宫产低风险组中合并医疗并发症的病例百分比显著更高（大学医院，16.9%；医院A，8.8%；医院B，9.8%；P = 0.001）。然而，各医院在低风险组的观察到的剖宫产率或标准化率方面均未检测到统计学差异。
病例组合模型为比较社区医院和大学医院的剖宫产率提供了一种更准确的方法。该模型中区分出的低风险患者群体代表了一个剖宫产率可能更能反映个体医疗实践模式而非孕产妇或胎儿风险的人群。
