Pay Your Dues Members Only Area
Central Surgical Association

49th Annual Meeting

Back to 2022 Abstracts


Socioeconomic status but not race is associated with survival after combined AVR/CABG in Medicare Beneficiaries
Justin M. Schaffer1, John J. Squiers1, Emily Shih1, Jasjit Banwait2, *Sarah Hale2, *Katherine B. Harrington1, J. Michael DiMaio1
1Baylor Scott & White - The Heart Hospital, Plano, Plano, Texas, United States, 2Baylor Scott & White Research Institute, Plano, Texas, United States


Objective: Race and socioeconomic status (SES) have both been shown to correlate with health outcomes; the interaction between these terms and their impact on long-term survival in cardiac surgery remains under-evaluated. The area deprivation index (ADI) is a measure of SES comprised of 17 census indicators available at the census block-group level. Race and socioeconomic status were evaluated in a large cohort of Medicare patients undergoing combined aortic valve replacement (AVR) and coronary artery bypass grafting (CABG).
Methods: We evaluated Medicare beneficiaries undergoing AVR/CABG from 1999-2015. Patients receiving aortic valve repair, root enlargement/replacement, or other concomitant procedures at the time of AVR/CABG were excluded from the analysis. SES was ascertained by linking a patient’s 9-digit zip code to the ADI of that geographic location, and ADI was divided into quintiles (e.g. top 20% SES corresponded to the lowest 1-20% ADI). A Cox regression analysis evaluated predictors of survival, with cubic spline analysis of the effect of ADI on survival. Long-term hazard for mortality was assessed with Kaplan-Meier analysis among patients in the lowest and highest quintiles of SES, as well as of different races, before and after inverse-probability of treatment weighting (IPTW) to adjust for confounding.
Results: Among 188,141 beneficiaries undergoing AVR/CABG, 93.9% self-identified as Caucasian, 3.1% Black, 1.0% Hispanic, and 0.5% Asian. Only 12.8% of Caucasian and 7.3% of Asian beneficiaries were in the lowest quintile of SES, as compared to 41.5% of Black and 31.9% of Hispanic beneficiaries. Cox regression analysis confirmed an interaction between race and ADI (p=0.003). Cubic spline analysis demonstrated a strong relationship between ADI percentile and survival, with lower SES linearly increasing the hazard for mortality (Figure A). Before accounting for SES and interaction between SES and race in the Cox regression analysis, Hispanic and Asian patients were found have a small but statistically significant hazard for death after surgery; after accounting for SES and its interaction with race, race was no longer significantly associated with survival. After adjusting for confounders using IPTW, patients in the lowest SES quintile had demonstrably worse survival as compared to patients from the top SES quintile (Figure B).
Conclusions: There is a strong interaction between race and SES as measured by ADI. Studies analyzing the impact of race on outcomes of cardiac surgery that do not account for SES are susceptible to significant confounding. The significant magnitude of and near-linear relationship between lower SES and increasing mortality after AVR/CABG suggest ADI should be adopted in the STS risk calculator and that resources should be devoted to patients with low SES to help improve outcomes after AVR/CABG.


Back to 2022 Abstracts