Impact of Patient Cost Sharing on Multiple Sclerosis Treatment

Objectives: To evaluate the impact of patient cost sharing on the probability of receiving disease-modifying therapies (DMTs) and treatment compliance among patients with multiple sclerosis (MS). Study Design: Retrospective claims-based study using Truven Health Analytics MarketScan Commercial and Medicare databases. Methods: Adult patients with MS with or without DMTs during January 1, 2004, to December 31, 2009, were identifi ed. Patients were assigned to low and high cost-sharing cohorts based on plan-level cost sharing for DMTs. Median cost sharing for DMTs ($ 29), standardized to 2010 US dollars, was used to determine the threshold between "low" and "high." The probability of receiving DMTs was assessed. The medication possession ratio (MPR) and risk of treatment discontinuation were evaluated during a 12-month follow-up period. A sensitivity analysis was conducted to evaluate the same outcomes for patients with cost sharing <$ 100, $ 101 to $ 200, and >$ 200. Results: A total of 14,497 treated (low cost sharing [n = 6954, 48.0%]; high cost sharing [n = 7543, 52.0%]), and 10,200 untreated patients (low cost-sharing [n = 4957, 48.6%]; high cost sharing [n = 5243, 51.4%]) were identifi ed. Compared with the low cost-sharing cohort, the high cost-sharing cohort had signifi cantly lower odds of receiving DMTs (odds ratio [OR] = 0.79, 95% confi dence interval [CI]: 0.74-0.84, P <. 0001), lower odds of treatment adherence (MPR > 80%) (OR = 0.87, 95% CI: 0.81-0.94, P =. 0006), and higher risk of treatment discontinuation (hazard ratio = 1.08, 95% CI: 1.02-1.15, P =. 0060). Sensitivity analysis confi rmed that higher cost-sharing was generally associated with worse outcomes. Conclusions: Higher cost sharing tends to result in suboptimal adherence or patients being left untreated. Such benefi t designs may increase health resource utilization as well as the risk of relapse and progressive disability.