Beck Dieter H, Smith Gary B, Pappachan John V, Millar Brian
Department of Anaesthesiology and Intensive Care, Charité Hospital, Humboldt University, Schumannstrasse 20-21, 10098 Berlin, Germany.
Intensive Care Med. 2003 Feb;29(2):249-56. doi: 10.1007/s00134-002-1607-9. Epub 2003 Jan 18.
External validation of three prognostic models in adult intensive care patients in South England. DESIGN. Prospective cohort study.
Seventeen intensive care units (ICU) in the South West Thames Region in South England.
Data of 16646 patients were analysed.
None.
We compared directly the predictive accuracy of three prognostic models (SAPS II, APACHE II and III), using formal tests of calibration and discrimination. The external validation showed a similar pattern for all three models tested: good discrimination, but imperfect calibration. The areas under the receiver operating characteristics (ROC) curves, used to test discrimination, were 0.835 and 0.867 for APACHE II and III, and 0.852 for the SAPS II model. Model calibration was assessed by Lemeshow-Hosmer C-statistics and was Chi(2 )=232.1 for APACHE II, Chi(2 )=443.3 for APACHE III and Chi(2 )=287.5 for SAPS II.
Disparity in case mix, a higher prevalence of outcome events and important unmeasured patient mix factors are possible sources for the decay of the models' predictive accuracy in our population. The lack of generalisability of standard prognostic models requires their validation and re-calibration before they can be applied with confidence to new populations. Customisation of existing models may become an important strategy to obtain authentic information on disease severity, which is a prerequisite for reliably measuring and comparing the quality and cost of intensive care.
对英格兰南部成年重症监护患者的三种预后模型进行外部验证。设计：前瞻性队列研究。
英格兰南部泰晤士河西南部地区的17个重症监护病房（ICU）。
分析了16646例患者的数据。
无。
我们使用校准和区分的正式测试，直接比较了三种预后模型（SAPS II、APACHE II和III）的预测准确性。外部验证显示，所测试的所有三种模型都有类似的模式：区分度良好，但校准不完善。用于测试区分度的受试者工作特征（ROC）曲线下面积，APACHE II和III分别为0.835和0.867，SAPS II模型为0.852。通过Lemeshow-Hosmer C统计量评估模型校准，APACHE II的卡方值为232.1，APACHE III为443.3，SAPS II为287.5。
病例组合的差异、结局事件的较高患病率以及重要的未测量患者混杂因素，可能是我们研究人群中模型预测准确性下降的原因。标准预后模型缺乏通用性，在能够自信地应用于新人群之前，需要对其进行验证和重新校准。定制现有模型可能成为获取疾病严重程度真实信息的重要策略，而这是可靠测量和比较重症监护质量与成本的前提条件。
