Norton E C, Garfinkel S A, McQuay L J, Heck D A, Wright J G, Dittus R, Lubitz R M
Department of Health Policy and Administration, School of Public Health, McGavran-Greenberg Hall, University of North Carolina, Chapel Hill 27599-7400, USA.
Health Serv Res. 1998 Dec;33(5 Pt 1):1191-210.
To examine the effect of hospital volume on in-hospital surgical outcomes for knee replacement using six years of Medicare claims data.
DATA SOURCES/STUDY SETTING: The data include inpatient claims for a 100 percent sample of Medicare patients who underwent primary knee replacement during 1985-1990. We supplemented these data with information from HCFA's denominator files, the Area Resource File, and the American Hospital Association survey files.
We estimated the probability that a patient has an in-hospital complication in the initial hospitalization for the first primary knee replacement, using a Logit model, for three definitions of complication. The models controlled for hospital volume, other hospital characteristics, patient demographics, and patient health status. We tested for the endogeneity of hospital volume.
DATA COLLECTION/EXTRACTION METHODS: A panel of two orthopaedic surgeons and two internists reviewed diagnosis codes to determine whether a complication was likely, possible, or due to anemia. After removing the few observations with bad or missing data, the final population has 295,473 observations.
The probability of a likely in-hospital complication declines rapidly from 53 through 107 operations per year, then levels off. Statistical tests imply that hospital volume is exogenous in this patient-level data. Complication rates increased steadily through the study period. Although obesity appeared to lower the probability of a complication, a counterintuitive result, further investigation revealed this to be an artifact of the claims data limit of listing no more than five diagnoses. Controlling for this restriction reversed the effect of obesity.
Rather than uncontrolled expansion of knee surgery to small hospitals, decentralization to regional centers where at least about 50, and preferably about 100, operations per year are assured appears to be the optimal policy to reduce in-hospital complications.
利用六年的医疗保险索赔数据，研究医院规模对膝关节置换术住院手术结果的影响。
数据来源/研究背景：数据包括1985 - 1990年间接受初次膝关节置换术的100%医疗保险患者的住院索赔。我们用来自医疗保健财务管理局（HCFA）的分母文件、地区资源文件和美国医院协会调查文件的信息对这些数据进行了补充。
我们使用Logit模型，针对三种并发症定义，估计患者在初次膝关节置换术首次住院期间发生院内并发症的概率。模型控制了医院规模、其他医院特征、患者人口统计学特征和患者健康状况。我们检验了医院规模的内生性。
数据收集/提取方法：由两名骨科外科医生和两名内科医生组成的小组审查诊断代码，以确定并发症是可能、很可能还是由贫血引起的。在去除少量数据质量差或缺失的数据观测值后，最终样本有295,473个观测值。
每年进行53至107例手术时，发生院内严重并发症的概率迅速下降，然后趋于平稳。统计检验表明，在这些患者层面的数据中，医院规模是外生的。在研究期间，并发症发生率稳步上升。尽管肥胖似乎降低了并发症的概率，这一结果有悖常理，但进一步调查发现这是索赔数据限制（最多列出五个诊断）造成的假象。控制这一限制后，肥胖的影响就逆转了。
为减少院内并发症，最佳政策似乎不是无节制地将膝关节手术扩展到小型医院，而是将手术分散到每年至少保证进行约50例、最好约100例手术的区域中心。
