Mediators of Black-White inequities in cardiovascular mortality among survivors of 18 cancers in the USA

Abstract

Background: This study aims to quantify Black-White inequities in cardiovascular disease (CVD) mortality among US survivors of 18 adult-onset cancers and the extent to which these inequities are explained by differences in socio-economic and clinical factors.

Methods: Survivors of cancers diagnosed at ages 20-64 years during 2007-16 were identified from 17 Surveillance, Epidemiology and End Results registries. Associations between race and CVD mortality were examined using proportional hazards models. Mediation analyses were performed to quantify the contributions of potential mediators, including socio-economic [health insurance, neighbourhood socio-economic status (nSES), rurality] and clinical (stage, surgery, chemotherapy, radiotherapy) factors.

Results: Among 904 995 survivors, 10 701 CVD deaths occurred (median follow-up, 43 months). Black survivors were more likely than White survivors to die from CVD for all 18 cancers with hazard ratios ranging from 1.30 (95% CI = 1.15-1.47) for lung cancer to 4.04 for brain cancer (95% CI = 2.79-5.83). The total percentage mediations (indirect effects) ranged from 24.8% for brain (95% CI=-5.2-59.6%) to 99.8% for lung (95% CI = 61.0-167%) cancers. Neighbourhood SES was identified as the strongest mediator for 14 cancers with percentage mediations varying from 25.0% for kidney cancer (95% CI = 14.1-36.3%) to 63.5% for lung cancer (95% CI = 36.5-108.7%). Insurance ranked second for 12 cancers with percentage mediations ranging from 12.3% for leukaemia (95% CI = 0.7-46.7%) to 31.3% for thyroid cancer (95% CI = 10.4-82.7%).

Conclusions: Insurance and nSES explained substantial proportions of the excess CVD mortality among Black survivors. Mitigating the effects of unequal access to care and differing opportunities for healthy living among neighbourhoods could substantially reduce racial inequities in CVD mortality among cancer survivors.

Keywords: Cancer survivorship; cardio-oncology; cardiovascular mortality; health insurance; neighbourhood socio-economic status; racial inequity.