J. Maxwell Chamberlain Paper for Perioperative and Critical Care: Insurance-Based Disparities in the Incidence of Cardiac Allograft Vasculopathy Following Heart Transplantation Are Mediated By Follow-Up Care at High Volume Centers

S. Sakowitz¹, S. Bakhtiyar², S. Mallick³, R. Shemin³, P. Benharash^4
1UCLA David Geffen School of Medicine, Los Angeles, California ²University of Colorado, Aurora, Colorado ³UCLA, Los Angeles, California ⁴UCLA Division of Cardiac Surgery, Los Angeles, California

Purpose: Individual and structural socioeconomic disadvantage are increasingly recognized to yield inferior patient and allograft outcomes following heart transplantation(HT). Importantly, some have hypothesized cardiac allograft vasculopathy (CAV) may contribute to such differences in long-term survival.[1-3] We sought to assess whether patient and community-level socioeconomic deprivation may shape CAV incidence and outcomes.

Methods: We considered all HT recipients≥18years within the 2004-2023 Organ Procurement and Transplantation Network(OPTN). Insurance was stratified as Private, Medicare, Medicaid, or Other (Veterans Affairs/other public insurance, free care, or self-pay). Neighborhood socioeconomic disadvantage was assessed using the Distressed Communities Index, a validated metric of community deprivation. CAV was defined as any evidence of angiographic coronary disease, as reported by transplant programs.[3] Institutional volume was computed, with hospitals in the highest tercile(N=55/161) considered High-Volume Centers(HVC).

We utilized Kaplan-Meier and Cox proportional-hazard models to evaluate CAV incidence. Covariates were automatically selected and included age, sex, race/ethnicity, body mass index, diabetes, smoking, OPTN status, transplant indication, immunosuppression, and allograft ischemia time, as well as donor age, sex, race, hypertension, and diabetes. To further adjust for potential confounders and baseline variation, we applied entropy balancing as a sensitivity analysis.

The primary endpoint was CAV at five-years following transplantation. We secondarily considered overall survival.

Results: Of 33,533 HT recipients, 20,899 (49%) were insured privately, 14,549 (34%) by Medicare, 5,583 (13%) Medicaid, and 1,522 (4%) other. On average, Medicaid patients were younger, more frequently of Black race, and more commonly diagnosed with dilated myopathy (Table).

Considering all patients, 10,505 (31%) developed CAV. Following comprehensive risk-adjustment for patient and neighborhood sociodemographic factors and clinical status, Medicaid insurance coverage was linked with significantly greater likelihood of developing CAV, relative to private insurance (Hazard Ratio[HR] 1.14, 95%Confidence Interval[CI] 1.03-1.27; FigureA). This remained true following entropy balancing (HR 1.13, CI 1.02-1.25). Neighborhood socioeconomic disadvantage was not independently associated with CAV hazard (HR 1.00, CI 0.99-1.00).

Upon analysis of overall outcomes over five-years, Medicaid remained independently linked with inferior patient (HR 1.32, CI 1.23-1.41; FigureB) and allograft survival (HR 1.31, CI 1.22-1.41).

We subsequently considered whether follow-up care at HVC might influence the association between Medicaid insurance and incidence of CAV. Notably, among patients receiving follow-up care at HVC, Medicaid insurance coverage was linked with similar likelihood of CAV development over five-years, compared to private insurance (HR 1.05, CI 0.60-1.85). Yet, considering those who had follow-up at non-HVC, Medicaid was associated with significantly greater CAV hazard (HR 1.28, CI 1.08-1.51).

Conclusion: Medicaid-insured recipients faced greater risk of CAV over five-years following heart transplantation, as well as inferior overall survival. This association persisted after adjustment for patient, donor, and transplant center characteristics, immunosuppression, and surrounding neighborhood disadvantage. However, follow-up care at high-volume transplantation programs, eliminated this insurance-based inequity in CAV incidence. This finding may suggest that high-quality follow-up care could allow for early identification and interventions against CAV risk factors. Altogether, our work underscores that socioeconomic factors should be considered as part of CAV risk stratification, and encourages closer follow-up and treatment for vulnerable populations in the months and years post-transplantation.

Identify the source of the funding for this research project: None