Medication cost concerns and disparities in patient-reported outcomes among a multiethnic cohort of patients with lupus

Objective: Concerns about the affordability of medications are common in systemic lupus erythematosus (SLE), but the relationship between medication cost concerns and health outcomes is poorly understood. We assessed the association of self-reported medication cost concerns and patient-reported outcomes (PROs) in a multiethnic lupus cohort.

Methods: The California Lupus Epidemiology Study is a cohort of individuals with physician-confirmed SLE. Medication cost concerns was defined as having difficulties affording lupus medications, skipping doses, delaying refills, requesting lower cost alternatives, purchasing medications outside the US, or applying for patient assistance programs. Linear regression and mixed effects models assessed the cross-sectional and longitudinal association of medication cost concerns and PROs, respectively, adjusting for age, sex, race and ethnicity, income, principal insurance, immunomodulatory medications, and organ damage.

Results: Of 334 participants, medication cost concerns were reported by 91 (27%). Medication cost concerns were associated with worse Systemic Lupus Erythematosus Activity Questionnaire (SLAQ, beta coefficient 5.9, 95% CI 4.3 to 7.6, P<0.001), Patient Health Questionnaire Depression Scale (PHQ-8, beta coefficient 2.7, 95% CI 1.4 to 4.0, P<0.001), and Patient-Reported Outcomes Measurement Information System (PROMIS, beta coefficient for physical function -4.6, 95% CI -6.7 to -2.4, P<0.001) scores after adjusting for covariates. Medication cost concerns were not associated with significant changes in PROs over two-year follow-up.

Conclusion: More than a quarter of participants reported at least one medication cost concern, which was associated with worse patient-reported outcomes. Our results reveal a potentially modifiable risk factor for poor outcomes rooted in the unaffordability of lupus care.