Association between medication adherence and non-drug healthcare utilisation and costs: a retrospective longitudinal cohort study among US women age 65 and older

Objectives To explore the association between hormone therapy (HT) adherence and non-drug healthcare utilisation and healthcare costs among patients with breast cancer. Design Retrospective longitudinal cohort study. Setting The US Medicare beneficiaries in the SEER-Medicare-linked database Participants Women aged >= 65 with hormone-receptor positive breast cancer from 2007 through mid-2009 in the USA. Interventions We examined the relationship between HT and adherence and outcomes of our interests. Primary and secondary outcome measures Our study cohort's HT adherence, non-drug healthcare utilisation and healthcare costs for the first year of HT and each year, thereafter, for a total of 5 years. Results 6045 eligible Medicare beneficiaries that met our selection criteria were included. We found that patients who were adherent to HT were associated with lower healthcare utilisation of all kinds (inpatient (0.35 vs 0.43, p<0.001), length of study during hospitalisation (4.19 vs 4.89, p<0.01), physician office visits (25.16 vs 26.17, p<0.001)), and significant reductions in many types of medical costs and neutral total healthcare costs despite the increased pharmacy costs. Half of the total medical cost reduction came from savings in hospitalisation costs. Conclusions Our study suggests that the added cost of HT adherence was all but offset by the reduced cost for other medical care. Our study provides evidence on the potential success of implementing value-based insurance design (VBID) plans among patients with breast cancer to improve their long-term oral medication adherence. Policymakers should consider adherence improvement strategies such as VBID plans, given that the costs likely will not surpass the total savings.