Mohammed Mohammed A, Manktelow Bradley N, Hofer Timothy P
Primary Care Clinical Sciences, University of Birmingham, Birmingham, UK
Department of Health Sciences, University of Leicester, Leicester, UK.
Stat Methods Med Res. 2016 Apr;25(2):706-15. doi: 10.1177/0962280212465165. Epub 2012 Nov 6.
There is interest in deriving case-mix adjusted standardised mortality ratios so that comparisons between healthcare providers, such as hospitals, can be undertaken in the controversial belief that variability in standardised mortality ratios reflects quality of care. Typically standardised mortality ratios are derived using a fixed effects logistic regression model, without a hospital term in the model. This fails to account for the hierarchical structure of the data - patients nested within hospitals - and so a hierarchical logistic regression model is more appropriate. However, four methods have been advocated for deriving standardised mortality ratios from a hierarchical logistic regression model, but their agreement is not known and neither do we know which is to be preferred. We found significant differences between the four types of standardised mortality ratios because they reflect a range of underlying conceptual issues. The most subtle issue is the distinction between asking how an average patient fares in different hospitals versus how patients at a given hospital fare at an average hospital. Since the answers to these questions are not the same and since the choice between these two approaches is not obvious, the extent to which profiling hospitals on mortality can be undertaken safely and reliably, without resolving these methodological issues, remains questionable.
人们对于得出病例组合调整后的标准化死亡率很感兴趣，这样一来，就可以对医疗服务提供者（如医院）之间进行比较，基于一种存在争议的观点，即标准化死亡率的差异反映了医疗质量。通常，标准化死亡率是使用固定效应逻辑回归模型得出的，模型中没有医院项。这未能考虑到数据的层次结构——患者嵌套在医院之中——因此层次逻辑回归模型更为合适。然而，有四种方法被提倡用于从层次逻辑回归模型中得出标准化死亡率，但它们之间的一致性尚不清楚，我们也不知道哪种方法更可取。我们发现这四种类型的标准化死亡率之间存在显著差异，因为它们反映了一系列潜在的概念性问题。最微妙的问题是，询问普通患者在不同医院的情况与询问特定医院的患者在普通医院的情况之间的区别。由于这两个问题的答案不同，而且在这两种方法之间做出选择并不明显，在不解决这些方法学问题的情况下，在多大程度上能够安全可靠地对医院死亡率进行剖析仍然存在疑问。
