Department of Anaesthesia and Perioperative Medicine, Auckland City Hospital, Auckland, New Zealand.
Orion Health, North Shore Hospital, Auckland, New Zealand.
Br J Surg. 2019 Oct;106(11):1549-1557. doi: 10.1002/bjs.11232. Epub 2019 Aug 6.
Many multivariable models to calculate mortality risk after surgery are limited by insufficient sample size at development or by application to cohorts distinct from derivation populations. The aims of this study were to validate the Surgical Outcome Risk Tool (SORT) for a New Zealand population and to develop an extended NZRISK model to calculate 1-month, 1-year and 2-year mortality after non-cardiac surgery.
Data from the New Zealand National Minimum Data Set for patients having surgery between January 2013 and December 2014 were used to validate SORT. A random 75 per cent split of the data was used to develop the NZRISK model, which was validated in the other 25 per cent of the data set.
External validation of SORT in the 360 140 patients who underwent surgery in the study period showed good discrimination (area under the receiver operating characteristic curve (AUROC) value of 0·906) but poor calibration (McFadden's pseudo-R 0·137, calibration slope 5·32), indicating it was invalid in this national surgical population. Internal validation of the NZRISK model, which incorporates sex and ethnicity in addition to the variables used in SORT for 1-month, 1-year and 2-year outcomes, demonstrated excellent discrimination with AUROC values of 0·921, 0·904 and 0·895 respectively, and excellent calibration (McFadden's pseudo-R 0·275, 0·308 and 0·312 respectively). Calibration slopes were 1·12, 1·02 and 1·02 respectively.
The SORT performed poorly in this national population. However, inclusion of sex and ethnicity in the NZRISK model improved performance. Calculation of mortality risk beyond 30 days after surgery adds to the utility of this tool for shared decision-making.
许多用于计算手术后死亡率的多变量模型存在发展过程中样本量不足或应用于与推导人群不同的队列的局限性。本研究的目的是验证新西兰人群的外科手术风险工具（SORT），并开发一种扩展的 NZRISK 模型来计算非心脏手术后 1 个月、1 年和 2 年的死亡率。
使用新西兰国家最低数据集（New Zealand National Minimum Data Set）中 2013 年 1 月至 2014 年 12 月期间接受手术的患者的数据来验证 SORT。数据集的 75%随机分割用于开发 NZRISK 模型，然后在数据集的其余 25%中验证该模型。
在研究期间接受手术的 360140 例患者中对 SORT 进行外部验证表明，该模型具有良好的区分度（接受者操作特征曲线下面积（area under the receiver operating characteristic curve, AUROC）值为 0.906），但校准效果较差（McFadden 伪 R 为 0.137，校准斜率为 5.32），表明该模型在这个全国性的手术人群中是无效的。对 NZRISK 模型的内部验证，该模型除了在 SORT 中用于 1 个月、1 年和 2 年结果的变量外，还纳入了性别和种族，结果显示其具有极好的区分度，AUROC 值分别为 0.921、0.904 和 0.895，且校准效果极好（McFadden 伪 R 分别为 0.275、0.308 和 0.312）。校准斜率分别为 1.12、1.02 和 1.02。
SORT 在这个全国性人群中的表现不佳。然而，在 NZRISK 模型中纳入性别和种族可以提高模型的性能。计算手术后 30 天以上的死亡率增加了该工具在共同决策中的效用。
