Blumberg M S
Kaiser Foundation Health Plan Inc., Oakland, CA 94612.
JAMA. 1991 Jun 12;265(22):2965-70.
This study examines whether the MedisGroups admission severity groups give unbiased estimates of 30-day mortality in 3037 Medicare-aged patients who were hospitalized in 1985 through 1986 with acute myocardial infarction. The average observed death rate for all acute myocardial infarction patients in the study who were in a given admission severity group was used to estimate the expected death probability for each case in a given group. (This is the same method used by the Pennsylvania Health Care Cost Containment Council for risk adjusting hospital mortality by diagnosis related groups in that state.) When compared with observed deaths, estimates of expected mortality were significantly biased for many patient attributes (eg, age, location of acute myocardial infarction, history of congestive heart failure, serum potassium level, serum urea nitrogen level, pulse rate, and blood pressure). These results are consistent with a conclusion that the MedisGroups scoring algorithm omits some important risk variables, inappropriately includes some other variables reflecting postadmission status, and gives the wrong weights to some appropriate risk variables. To the extent that these findings are also applicable to current MedisGroups scoring algorithms and to other conditions and procedures, MedisGroups admission severity groups cannot fairly adjust for interhospital case mix differences in outcome studies.
本研究调查了MedisGroups入院严重程度分组能否对1985年至1986年因急性心肌梗死住院的3037名老年医疗保险患者的30天死亡率给出无偏估计。研究中处于特定入院严重程度分组的所有急性心肌梗死患者的平均观察死亡率用于估计给定分组中每个病例的预期死亡概率。（这与宾夕法尼亚州医疗保健成本控制委员会在该州按诊断相关分组对医院死亡率进行风险调整时使用的方法相同。）与观察到的死亡情况相比，预期死亡率的估计在许多患者特征方面（如年龄、急性心肌梗死部位、充血性心力衰竭病史、血清钾水平、血清尿素氮水平、脉搏率和血压）存在显著偏差。这些结果支持以下结论：MedisGroups评分算法遗漏了一些重要的风险变量，不适当地纳入了一些反映入院后状况的其他变量，并且对一些适当的风险变量赋予了错误的权重。就这些发现也适用于当前的MedisGroups评分算法以及其他疾病和治疗程序而言，MedisGroups入院严重程度分组无法在结局研究中公平地调整医院间病例组合差异。
