Impact of pharmacy channel on adherence to oral oncolytics

BACKGROUND: Oral chemotherapy is increasingly prescribed to treat cancer. Despite its benefits, concerns have been raised regarding adherence to therapy. The study objective was to compare and measure adherence, persistence, and abandonment in patients filling prescriptions in traditional retail (TR) versus specialty pharmacy (SP) channels. METHODS: Using a retrospective cohort design, we selected newly treated patients aged ≥18 years with a prescription for erlotinib, capecitabine, or imatinib during 2007–2011 from a Medco population of both United States commercial and Medicare health plans. Patients were classified according to pharmacy channel providing the medication. Abandonment was defined as a reversal following initial approval of the index prescription claim with no additional paid claims for agent within 90 days of reversal. Patients were considered adherent if the proportion of days covered between the date of the first and last oral prescription was ≥80%. RESULTS: In our retrospective cohort, 11,972 filled their prescriptions within the SP channel, and 30,394 filled their prescriptions within the TR channels, respectively. The SP channel had the highest proportion of adherent patients compared with TR (71.6% vs. 56.4%, P < .001). Abandonment of the initial prescription was low with overall rates of only 1.7%. In multivariate models controlling for demographic characteristics, index oncolytic, days of supply, and copay, SP channel (relative to TR) was significantly associated with lower rates of abandonment and increased adherence. CONCLUSIONS: Pharmacy channel may be influential on abandonment and adherence. Lower rates of abandonment and higher rates of adherence were observed among SP patients versus TR. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12913-017-2373-2) contains supplementary material, which is available to authorized users.