Compliance and Persistence of Antidepressants Versus Anticonvulsants in Patients With Neuropathic Pain During the First Year of Therapy

Background: Neuropathic pain (NP) is a chronic condition that has human, social, and economic consequences. A variety of agents can be used for treatment; however, antidepressants and anticonvulsants are the 2 classes most widely studied and represent first-line agents in the management of NP. Little information is known about the adherence patterns of these medications during the first year of therapy in patients with NP. Objective: To examine the compliance and persistence of antidepressants versus anticonvulsants in patients with NP during the first year of therapy. Methods: Using electronic medical and pharmacy data for the Kaiser Permanente Southern California region, the adherence patterns for patients with a NP diagnosis prescribed an antidepressant or an anticonvulsant were studied. Compliance and persistence were measured using the medication possession ratio and the Refill-Sequence model, respectively. Results: The study included 1817 patients with NP diagnosis taking either an antidepressant or an anticonvulsant. Within the antidepressant group, 42.9% were considered compliant, compared with 43.7% in the anticonvulsant group. Subanalysis of the 2 cohorts revealed that patients on venlafaxine were the most compliant (69.4%) compared with patients taking gabapentin (44.4%) and tricyclic antidepressants (41.8%) (P<0.01). Only 21.2% of patients in the antidepressant group and 21.4% in the anticonvulsant group were considered persistent with their medication refills. Discussion: Compliance and persistence rates were similar for patients with NP diagnosis taking antidepressants and anticonvulsants. Higher compliance was observed among patients taking venlafaxine; however, this population did have a small sample size.