Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
J Vasc Surg. 2011 Jan;53(1):1-5. doi: 10.1016/j.jvs.2010.08.031. Epub 2010 Nov 18.
Hospital quality in vascular surgery is often measured using mortality. We sought to determine whether adjusting mortality for statistical reliability changes hospital quality rankings for vascular surgery.
Patients undergoing five common vascular surgery procedures (open and endovascular abdominal aortic aneurysm repair, carotid endarterectomy, lower extremity bypass, and aorto-femoral bypass) in the National Surgical Quality Improvement Project (NSQIP) in 2007 were identified (n = 14,559). For each hospital, we first calculated a ratio of observed to expected mortality (O-E ratio) using standard NSQIP techniques. We then adjusted these estimates for statistical noise using empirical Bayes methods, a technique known as reliability adjustment. We then compared rankings based on the standard O-E ratio to the rankings after reliability adjustment.
A total of 172 hospitals reported an average adjusted mortality rate of 2.4% for the five procedures, varying from 0% to 17%. After adjusting for statistical noise using reliability adjustment, hospital mortality was greatly diminished, varying only from 1.7% to 4.1%. This adjustment for reliability had a dramatic effect on hospital rankings. Overall, 43% of hospitals were reclassified into either a higher or lower quartile of performance using traditional methods of risk-adjustment. Fifty-one percent all hospitals in the "best" quartile of performance according to traditional O-E ratios are not classified in the "best" quartile after adjusting for statistical noise. Twenty-six percent of hospitals in the "worst" quartile were no longer classified as such after adjusting for noise.
Adjusting mortality for reliability reduces statistical noise and provides more stable estimates of hospital quality. Reliability adjustment should be standard for comparing hospital quality.
血管外科的医院质量通常通过死亡率来衡量。我们试图确定，通过统计可靠性调整死亡率是否会改变血管外科的医院质量排名。
在 2007 年的国家外科质量改进计划（NSQIP）中，确定了接受五种常见血管外科手术（开放和血管内腹主动脉瘤修复、颈动脉内膜切除术、下肢旁路和主动脉-股旁路）的患者（n=14559）。对于每家医院，我们首先使用标准 NSQIP 技术计算观察到的与预期死亡率之比（O-E 比）。然后，我们使用经验贝叶斯方法（一种称为可靠性调整的技术）对这些估计值进行统计噪声调整。然后，我们比较了基于标准 O-E 比的排名和可靠性调整后的排名。
共有 172 家医院报告了这五种手术的平均调整后死亡率为 2.4%，从 0%到 17%不等。通过使用可靠性调整来调整统计噪声，医院死亡率大大降低，仅从 1.7%到 4.1%不等。这种对可靠性的调整对医院排名产生了巨大影响。总体而言，使用传统的风险调整方法，43%的医院重新分类为性能较高或较低的四分位数。根据传统 O-E 比，51%的所有医院都属于“最佳”四分位数，在调整统计噪声后，不再属于“最佳”四分位数。调整噪声后，26%的“最差”四分位医院不再被归类为最差。
通过可靠性调整死亡率可以减少统计噪声，并提供更稳定的医院质量估计。可靠性调整应成为比较医院质量的标准。
