Department of Surgery, University of Massachusetts Medical School, Worcester, Mass 01655, USA.
J Vasc Surg. 2011 Mar;53(3):591-599.e2. doi: 10.1016/j.jvs.2010.09.063. Epub 2010 Dec 8.
Studies analyzing the effects of volume on outcomes after abdominal aortic aneurysm (AAA) repair have primarily centered on institutional volume and not on individual surgeon volume. We sought to determine the relative effects of both surgeon and institution volume on mortality after open and endovascular aneurysm repair (EVAR) for intact AAAs.
The Nationwide Inpatient Sample (2003-2007) was queried to identify all patients undergoing open repair and EVAR for nonruptured AAAs. To calculate surgeon and institution volume, 11 participating states that record a unique physician identifier for each procedure were included. Surgeon and institution volume were defined as low (first quintile), medium (second, third, or fourth quintile), and high (fifth quintile). Stratification by institution volume and then by surgeon volume was performed to analyze the primary endpoint: in-hospital mortality. Multivariable models were used to evaluate the association of institution and surgeon volume with mortality for open repair and EVAR, controlling for potential confounders.
During the study period, 5972 open repairs and 8121 EVARs were performed. For open AAA repair, a significant mortality reduction was associated with both annual institution volume (low <7, medium 7-30, and high >30) and surgeon volume (low ≤ 2, medium 3-9, and high >9). High surgeon volume conferred a greater mortality reduction than did high institution volume. When low and medium volume institutions were stratified by surgeon volume, mortality after open AAA repair was inversely proportional to surgeon volume (8.7%, 3.6%, and 0%; P < .0001, for low, medium, and high-volume surgeons at low-volume institutions; and 6.7%, 4.8%, and 3.3%; P = .02, for low, medium, and high-volume surgeons at medium-volume institutions). High-volume institutions stratified by surgeon volume demonstrated the same trend (5.1%, 3.4%, and 2.8%), but this finding was not statistically significant (P = .57). Multivariable analysis was confirmatory: low surgeon volume independently predicted mortality (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.3-3.1; P < .001); low institution volume did not (P = .1). For EVAR, neither institution volume nor surgeon volume influenced mortality (univariate or multivariable).
The primary factor driving the mortality reduction associated with case volume after open AAA repair is surgeon volume, not institution volume. Regionalization of AAAs should focus on open repair, as EVAR outcomes are equivalent across volume levels. Payers may need to re-evaluate strategies that encourage open AAA repair at high-volume institutions if specific surgeon volume is not considered.
分析腹主动脉瘤（AAA）修复术后容量对结局影响的研究主要集中在机构容量上，而不是个体外科医生的容量上。我们旨在确定外科医生和机构容量对开放性和血管内动脉瘤修复术（EVAR）治疗完整 AAA 的死亡率的相对影响。
通过全美住院患者样本（2003-2007 年）查询所有接受非破裂性 AAA 开放修复和 EVAR 的患者。为了计算外科医生和机构的容量，纳入了记录每个手术唯一医生标识符的 11 个参与州。外科医生和机构的容量定义为低（第一五分位数）、中（第二、第三或第四五分位数）和高（第五五分位数）。通过机构容量分层，然后通过外科医生容量分层，分析主要终点：住院死亡率。使用多变量模型评估机构和外科医生容量与开放性修复术和 EVAR 死亡率之间的关联，同时控制潜在的混杂因素。
在研究期间，进行了 5972 例开放性修复术和 8121 例 EVAR。对于开放性 AAA 修复术，与每年机构容量（低<7、中 7-30 和高>30）和外科医生容量（低≤2、中 3-9 和高>9）均显著降低死亡率相关。高外科医生容量比高机构容量更能降低死亡率。当低和中容量机构按外科医生容量分层时，开放性 AAA 修复术后的死亡率与外科医生容量成反比（低容量机构中低、中、高容量外科医生分别为 8.7%、3.6%和 0%；P<0.0001；中容量机构中低、中、高容量外科医生分别为 6.7%、4.8%和 3.3%；P=0.02）。按外科医生容量分层的高容量机构也表现出相同的趋势（5.1%、3.4%和 2.8%），但这一发现没有统计学意义（P=0.57）。多变量分析是确认性的：低外科医生容量独立预测死亡率（比值比[OR]，2.0；95%置信区间[CI]，1.3-3.1；P<0.001）；低机构容量则没有（P=0.1）。对于 EVAR，机构容量或外科医生容量都没有影响死亡率（单变量或多变量）。
与开放性 AAA 修复术后容量相关的死亡率降低的主要因素是外科医生容量，而不是机构容量。AAA 的区域化应集中在开放性修复术上，因为 EVAR 的结果在容量水平上是等效的。如果不考虑特定外科医生的容量，支付者可能需要重新评估鼓励在高容量机构进行开放性 AAA 修复的策略。
