Abstract / Summary
Background: Medication adherence rates across diseases that require immunosuppression, including autoimmune diseases, are low. While cost barriers affect medication adherence, it is unknown whether adherence rates related to cost barriers differ between medically immunosuppressed patients and similar patients with other chronic diseases. The purpose of this study is to evaluate the influence of immunosuppression on cost-related medication non-adherence (CRMNA). Methods: We performed a cross-sectional study utilizing the National Health Interview Survey (NHIS). Multivariable logistic regression was used to evaluate the association between immunosuppression and CRMNA, accounting for sex, age, education, race, income, life satisfaction, insurance status and marital status. Predicted probabilities of CRMNA were estimated by age group, and a subgroup analysis was performed among people who described as having poor health. Results: In our unweighted sample of 17,394 adults, 54.3% were female, 12.8% self-identified as Black, 35.2% were publicly insured (Medicare and/or Medicaid), and 11.1% were below the federal poverty level. The prevalence of reporting CRMNA was 11% for patients with chronic diseases and no immunosuppression, 12.5% for patients with immunosuppression but no chronic disease, and 19.1% for patients with chronic disease and immunosuppression. In the multivariable model, participants with medical immunosuppression and chronic diseases were more likely to report CRMNA than participants with chronic diseases but no immunosuppression (OR 1.55, 95% CI [1.24, 1.94], p = 0.001). Participants with medical immunosuppression but no chronic disease did not differ significantly from the group with chronic diseases and no immunosuppression (OR 0.87, 95% CI [0.60, 1.29], p = 0.49). The predicted probability of CRMNA was highest for 30–49-year-old immunosuppressed individuals with one or more chronic diseases at 23%. CRMNA was similarly associated with immunosuppression status in patients with poor health. Conclusions: Medically immunosuppressed individuals with chronic disease experience greater CRMNA than individuals with chronic disease who are not immunosuppressed, particularly among individuals 30–49 years of age. Future studies aimed at reducing CRMNA in immunosuppressed individuals may consider interventions that target the role of chronic health conditions in non-adherence.