Hospital Volume and Social Determinants of Health Do Not Impact Outcomes in Fenestrated Visceral Segment Endovascular Aortic Repair for Patients Treated at VQI Centers

Abstract

Objective

The purpose of this study is to investigate the impact of social determinants of health on access to high volume centers and clinical outcomes in fenestrated abdominal aortic endografting. Further, the effect of center volume in fenestrated endografting on outcomes will be sought as this is ill defined. The data herein have the potential to affect referral patterns and locations of complex fenestrated aortic aneurysm care. If lower volume centers achieve equivalent outcomes to higher volume centers, then limiting access to a small number of centers may not be justified.

Methods

Vascular Quality Initiative (VQI) was utilized as the data source. Four adverse outcomes categories were investigated : (1) Lack of follow up data in the VQI database at 1 year postoperatively; (2) Thirty day operative mortality; (3) Composite perioperative adverse event outcome; and (4) Twelve month mortality. Social determinants of health exposure variables included rural status, non-metropolitan living area, highest and lowest decile and quintile area deprivation index, insurance status, and non-home living status. Designated categories were created for patients operated on in centers within the top 25% of case volume, centers in the bottom 25% of case volume, and in centers with less than 10 total fenestrated endograft cases. Univariable analyses were performed with Chi-squared testing for categorical variables and t test for comparison of means. Multivariable binary logistic regression was performed to identify risks for the composite adverse perioperative event.

Results

There was no statistically significant association with the composite adverse perioperative event category, 30-day mortality or 12-month mortality for any of the social determinants of health or center volume categories. Patients who live in rural areas (P = .029) and patients with Military/VA insurance (P < .001) were significantly more likely to be lost to follow up at their index VQI center at 1 year. When accounting for all standard co-morbidities, none of the following variables had any significant association with the composite adverse perioperative event on multivariable analysis: absolute center volume as an ordinal variable (P = .985); procedure at a bottom 25^th percentile volume center (P = .214); procedure at a center with less than 10 total fenestrated cases in the database (P = .521); rural home status (P = .622); remote from metropolitan home status (P = .619); highest 10% ADI (P = .903); highest 20% ADI (P = .219); Lowest 10% of ADI (P = .397). The variables that had a statistically significant multivariable association with the composite adverse event were 3 or 4 visceral vessels stented vs 2 vessels (P < .001), baseline renal insufficiency (P < .001), female sex (P < .001), ESRD on dialysis (P = .002), and history of coronary revasculizaiton (P = .047). There was noted to be a statistically significant (P < .01) increase in 30 day mortality, composite adverse perioperative event, and 12 month mortality in moving from 2 to 3 to 4 fenestrated stented vessels. However, amongst patients who were treated with 3 and 4 vessel fenestrated stenting, patients treated at bottom 25^th percentile centers and centers with less than 10 total cases did not experience a higher rate of composite adverse perioperative event, 30 day mortality, or 12 month mortality relative to top 25% volume centers indicating safety of these procedures in lower volume centers.

Conclusions

Social determinants of health and center volume do not impact outcomes in fenestrated visceral segment aortic endograft procedures performed at centers participating in the Vascular Quality Initiative. There is progressive morbidity and mortality in moving from 2 to 3 to 4 visceral stents and fenestrations, however lower volume centers within VQI achieve equivalent outcomes to high volume centers in performing 3 and 4 vessel visceral fenestrated stent cases. Female sex, ESRD, prior coronary revascularization, and baseline renal insufficiency portend an increased risk for perioperative morbidity for fenestrated visceral segment aortic endografting.