The association between cost sharing, prior authorization, and specialty drug utilization: A systematic review

BACKGROUND: Specialty drugs are identified by high monthly costs and complexity of administration. Payers use utilization management strategies, including prior authorization and separate tiers with higher cost sharing, to control spending. These strategies can negatively impact patients’ health outcomes through treatment initiation delays, medication abandonment, and nonadherence. OBJECTIVE: To examine the effect of patient cost sharing on specialty drug utilization and the effect of prior authorization on treatment delay and specialty drug utilization. METHODS: We conducted a literature search in the period between February 2021 and April 2022 using PubMed for articles published in English without restriction on date of publication. We included research papers with prior authorization and cost sharing for specialty drugs as exposure variables and specialty drug utilization as the outcome variable. Studies were reviewed by 2 independent reviewers and relevant information from eligible studies was extracted using a standardized form and approved by 2 reviewers. Review papers, opinion pieces, and projects without data were excluded. RESULTS: Forty-four studies were included in this review after screening and exclusions, 9 on prior authorization and 35 on cost sharing. Patients with lower cost sharing via patient support programs experienced higher adherence, fewer days to fill prescriptions, and lower discontinuation rates. Similar outcomes were noted for patients on low-income subsidy programs. Increasing cost sharing above $100 was associated with up to 75% abandonment rate for certain specialty drugs. This increased level of cost sharing was also associated with higher discontinuation rates and odds. At the same time, decreasing out-of-pocket costs increased initiation of specialty drugs. However, inconsistent results on impact of cost sharing on medication possession ratio (MPR) and proportion of days covered (PDC) were reported. Some studies reported a negative association between higher costs and MPR and PDC; however, MPR and PDC of cancer specialty drugs did not decrease with higher costs. Significant delays in prescription initiation were reported when prior authorization was needed. CONCLUSIONS: Higher levels of patient cost sharing reduce specialty drug use by increasing medication abandonment while generally decreasing initiation and persistence. Similarly, programs that reduce patient cost sharing increase initiation and persistence. In contrast, cost sharing had an inconsistent and bidirectional effect on MPR and PDC. Prior authorization caused treatment delays, but its effects on specialty drug use varied. More research is needed to examine the effect of cost sharing and prior authorization on long-term health outcomes.