Söderlund N, Gray A, Milne R, Raftery J
Department of Public Health and Primary Care, University of Oxford.
J Health Serv Res Policy. 1996 Jan;1(1):10-9. doi: 10.1177/135581969600100104.
The introduction of an internal market in the British National Health Service (NHS) has highlighted the importance of developing appropriate, valid and timely measures of hospital activity, both for the purposes of specifying and monitoring contracts and for evaluating the success of the NHS reforms in general. This paper compares the validity of five case mix methods (Diagnosis Related Groups (DRGs); Healthcare Resource Groups (HRGs) versions 1 and 2; specialty classification; a simple age categorization) in predicting resource use.
Two data sets were used to compare different case mix methods. A 3% random sample (n approximately equal to 300,000) of the 1992/3 Hospital Episodes Statistics was used to test their ability to predict variation in length of stay, and a second set of individually costed patient episodes from two hospitals (n approximately equal to 40,000) was used to test their ability to explain cost variation. Analysis of variance models were used to assess the fit of each of the case mix systems to test data and a simple significance test of differences in mean squared error between models was applied.
All case mix methods performed poorly on untrimmed data. When lengths of stay greater than 29 days were excluded, version 2 of HRGs explained 31% of total variance in length of stay and 25% of cost variation. DRGs explained less variance but performed better than HRGs version 1. For a typical hospital patient population consisting of a range of specialties, the difference in explanatory power between HRGs V2 and DRGs was statistically significant at the 5% level for sample sizes of approximately 2000 or greater. For individual specialties, the minimum sample size required for the difference between the groupers to be significant ranged from around 300 to over 2000.
The locally developed HRGs version 2 system appears to offer superior performance in terms of resource homogeneity to other currently available approaches. It is also more adaptable and cheaper than imported alternatives and has been formally endorsed by the UK medical Royal Colleges.
英国国家医疗服务体系（NHS）引入内部市场，凸显了制定适当、有效且及时的医院活动衡量标准的重要性，这既用于明确和监督合同，也用于总体评估NHS改革的成效。本文比较了五种病例组合方法（诊断相关分组（DRGs）；医疗资源分组（HRGs）第1版和第2版；专科分类；简单年龄分类）在预测资源使用方面的有效性。
使用两个数据集来比较不同的病例组合方法。1992/3年医院诊疗统计数据的3%随机样本（n约等于300,000）用于测试它们预测住院时间差异的能力，另一组来自两家医院的单独计算成本的患者诊疗记录（n约等于40,000）用于测试它们解释成本差异的能力。方差分析模型用于评估每种病例组合系统与测试数据的拟合度，并对模型之间的均方误差差异进行简单显著性检验。
所有病例组合方法在未修剪数据上表现不佳。当排除住院时间超过29天的情况后，HRGs第2版解释了住院时间总方差的31%和成本差异的25%。DRGs解释的方差较少，但表现优于HRGs第1版。对于包含一系列专科的典型医院患者群体，当样本量约为2000或更大时，HRGs V2和DRGs在解释力上的差异在5%水平上具有统计学显著性。对于个别专科，分组器之间差异具有显著性所需的最小样本量范围从约300到超过2000。
本地开发的HRGs第2版系统在资源同质性方面似乎比其他现有方法表现更优。它也比进口替代方案更具适应性且成本更低，并已得到英国医学皇家学院的正式认可。
