Association of Patient Cost-Sharing with Adherence to GLP-1a and Adverse Health Outcomes

Objective To examine the associations between patient out-of-pocket (OOP) costs and non-adherence to glucagon-like peptide-1 receptor agonists (GLP-1a), and the consequent impact on adverse outcomes including hospitalizations and emergency department (ED) visits. Research Design and Methods This retrospective cohort study utilized MarketScan® Commercial data (2016 - 2021). The cohort included non-pregnant adults aged 18–64 years with type 2 diabetes who initiated GLP-1a therapy. Participants were continuously enrolled in the same private insurance plan for six months before the prescription date and one year thereafter. Exposures included average first 30-day OOP costs for GLP-1a, categorized into quartiles (lowest [Q1] to highest [Q4]). Primary outcomes were the annual proportion of days covered (PDC) for GLP-1a and non-adherence, defined as PDC < 0.8. Secondary outcomes included diabetes-related and all-cause hospitalizations and ED visits one-year post-GLP-1a initiation. Results Among 61,907 adults initiated GLP-1a, higher 30-day OOP costs were associated with decreased adherence. Patients in the highest OOP cost quartile (Q4: $80–$3,375) had significantly higher odds of non-adherence (OR: 1.25; 95% CI: 1.19–1.31) compared to those in the lowest quartile (Q1: $0–$21). Non-adherence was linked to increased incidence rates of diabetes-related hospitalizations or ED visits (IRR: 1.86; 95% CI: 1.43–2.42), cumulative length of hospitalization (IRR: 1.56; 95% CI: 1.41–1.72), all-cause ED visits (IRR: 1.38; 95% CI: 1.32–1.45), and increased ED-related costs ($69.81, 95% CI: $53.54–$86.08). Conclusions Higher OOP costs for GLP-1a were associated with reduced adherence and increased rates of adverse outcomes among type 2 diabetes patients.