Medication adherence and contributing factors among cancer survivors with cardiovascular disease

Background Cardiovascular disease (CVD) is the leading cause of non-cancer mortality among cancer survivors. CVD incidence is about twice as high in cancer survivors as in the general population, likely driven by cardiotoxic cancer therapies and shared risk factors like smoking and obesity. Among those with known CVD, adherence to CVD medications often declines following a cancer diagnosis. Previous studies found higher non-adherence in younger ages, females, and those with high copayment insurance but reported mixed findings for other sociodemographic factors and comorbidity burden. This study investigates determinants of suboptimal adherence to CVD medications among cancer survivors with CVD. Method We used nationally representative data from the pooled 2010-2022 Medical Expenditure Panel Survey. The primary outcome was CVD medication adherence, defined as the proportion of days covered ([total days supplied ÷365]×100) of ≥80%. Logistic regression was used to estimate associations between medication adherence and individual sociodemographic, access to medication, and health-related factors, adjusting for potential confounders. Results Approximately 70% of cancer survivors aged ≥18 years had CVD (N=18,461). In adjusted models, CVD medication adherence among cancer survivors was lower in ages 18-44 (adjusted OR [AOR]=0.51, 95%CI=0.37,0.71) and 45-64 (AOR=0.79, 95%CI=0.70,0.90) than ages ≥65 years; females (AOR=0.79, 95%CI=0.70,0.88) than males; and those with a high school diploma (AOR=0.80, 95%CI=0.70,0.92), some college education (AOR=0.78, 95%CI=0.67,0.90), or a bachelor's or higher degree (AOR=0.72, 95%CI=0.62,0.84) than those with less than high school education. Adherence was also lower among cancer survivors who only used community pharmacies (AOR=0.82, 95%CI=0.69,0.98) than those who have ever used mail order or online pharmacies. Adherence was higher among cancer survivors in the Midwest (AOR=1.27, 95%CI=1.10,1.47) and South (AOR=1.23, 95%CI=1.08,1.40) than West; those with comorbidity score of 3 (AOR=1.23, 95%CI=1.02,1.48) than comorbidity score of zero; and those taking ≥5 medications (AOR=2.32, 95%CI=2.07,2.59) than taking <5 medications. Other factors including race and ethnicity, marital status, income, employment status, health insurance, activity limitation, self-reported health status, and type of cancer were not associated with adherence in adjusted models. Conclusions CVD medication adherence among cancer survivors was lower among young adults; women; individuals with higher education, multiple chronic conditions, limited access to mail-order or online pharmacies, or managing multiple medications; and in the Midwest and South regions. Targeted interventions are needed to improve cardiovascular medication adherence and long-term health outcomes in cancer survivors.