Kamble PS, Walker DR, Marx S, Harvey R, Uribe CL, Bunniran S, Collins J. Adherence and discontinuation rates of sofosbuvir-based regimens: modeling real world experience in a large managed care organization. Poster presented at the 2015 66th Annual Meeting of the American Association for the Study of Liver Diseases; November 2015. San Francisco, CA. [abstract] Hepatology. 2015 Oct; 62(S1):723A-4A. doi: 10.1002/hep.28228.

BACKGROUND: Discontinuation (DC) rates of sofosbuvir (SOF) based medications are generally very low in clinical trials (< 1%). Adherence (ADH) rates on the other hand are rarely reported in clinical trials. Only a handful of studies have examined this issue outside of clinical trials, however, those studies did not comprehensively attempt to adjust for factors that may impact DC and ADH rates.

OBJECTIVES: The objective was to assess medication ADH and DC rates in SOF-based regimens and identify factors potentially associated with poor ADH and DC rates in patients with the hepatitis C virus (HCV).

METHODS: A retrospective cohort study using administrative claims data from a large managed care organization from May 2013 to Sept 2014. Plan types included Medicare Advantage Prescription Drug (MAPD) and commercial (COM) which provide medical and pharmacy benefits. The study cohort included patients initiating 12 or 24-week treatment on SOF. The index date was defined as the first prescription fill date for SOF from Nov 2013 to March or May 2014 with a follow up period of 12 or 24 weeks. Continuous enrollment for 6 months pre-index and 4 or 6 months post index date was required. ADH was calculated using proportion of days covered (PDC). Patients with at least 85% PDC were categorized as adherent. Patients were deemed discontinued if a gap of > 14 days exists between fills. Regression analyses were conducted to identify baseline covariates associated with ADH or DC among plan members. Covariates included age, gender, risk score, plan type, geographic region, treatment co-pay, prior treatment experience, use of interferon, treatment duration and baseline healthcare use and costs.

RESULTS: In total, 514 MAPD and 63 COM members initiated HCV treatment with DAA. Patients were 63% male, mean age of 60 years, 84% on 12-week treatment, and 36% of SOF members were also on peginteferon. The discontinuation rate was 18% and the percent of members considered non-adherent was 14%. Based on the regression analysis, only older age, higher comorbidity risk score and use of peginterferon were significantly positively associated with non-adherence after controlling for other covariates. For 12-week treatment patients, being in a non-HMO plan or in Medicare were predictors of being at lower risk of medication discontinuation.

CONCLUSIONS: In a real world setting, 14% of members on a new DAA are not adherent and 18% had fill gaps greater than 14 days. Sicker, older members are less likely to be adherent, whereas non-HMO and MAPD members have lower risk of discontinuation. Additional patient support may be needed to optimize ADH in these patients.

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