What is the probability of detecting poorly performing hospitals using funnel plots?
What is the probability of detecting poorly performing hospitals using funnel plots?
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DOI：
10.1136/bmjqs-2012-001689
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发表时间：
2013-10-01
影响因子：
5.4
通讯作者：
Manktelow, Bradley N.
中科院分区：
文献类型：
--
作者：
Seaton, Sarah E.;Barker, Lisa;Manktelow, Bradley N.
最近在英国备受瞩目的病例突出了临床结果报告对医疗保健提供者和患者的影响。非常重视使用统计方法来确定观察到的不良表现的医疗保健提供者。这些供应商被强调为潜在的离群值，并调查了可能的原因。因此，正确理解和解释用于识别离群值的方法至关重要。虽然患者、资助者、管理者和临床团队确实想知道提供者的真实基本表现，但这种真实表现通常无法直接知道，必须使用观察到的结果进行估计。然而，由于机会变化，真实性能和观察到的性能之间的差异可能会出现。临床结局通常通过标准化死亡率（SMR）报告，使用漏斗图显示。观察到的SMR福尔斯超出漏斗图控制限的供应商将被确定为潜在离群值。然而，虽然显然期望应当识别具有与预期不同的真实基本性能的医疗保健提供者，但是先前尚未描述将从观察到的SMR识别出它的实际概率。在这里，我们表明，当预期的事件数量很小时，应谨慎使用SMR的漏斗图，因为识别出真正表现不佳的供应商的概率可能很小。另一方面，当预期的事件数量很大时，必须小心，因为即使其分歧很小或没有临床重要性，也可能将提供者识别为离群值。
Recent high profile cases in the UK have highlighted the impact that the reporting of clinical outcomes can have for healthcare providers and patients. Great importance has been placed on the use of statistical methods to identify healthcare providers with observed poor performance. Such providers are highlighted as potential outliers and the possible causes investigated. It is crucial, therefore, that the methods used for identifying outliers are correctly understood and interpreted. While patients, funders, managers and clinical teams really want to know the true underlying performance of the provider, this true performance generally cannot be known directly and must be estimated using observed outcomes. However, differences between the true and observed performance are likely to arise due to chance variation. Clinical outcomes are often reported through the standardised mortality ratio (SMR), displayed using funnel plots. Providers whose observed SMR falls outside the funnel plot control limits will be identified as potential outliers. However, while it is obviously desirable that a healthcare provider with a true underlying performance different from that expected should be identified, the actual probability that it will be identified from observed SMRs has not previously been described. Here we show that funnel plots for the SMR should be used with caution when the expected number of events is small as the probability of identifying providers with true poor performance is likely to be small. On the other hand, when the expected number of events is large, care must be taken as a provider may be identified as an outlier even when its divergence is of little or no clinical importance.