Medication adherence and healthcare costs among patients with diabetic peripheral neuropathic pain initiating duloxetine versus pregabalin.

Objective: To examine the impact of medication choice between duloxetine or pregabalin on medication adherence and direct healthcare costs among patients with diabetic peripheral neuropathic pain (DPNP).
Methods: A retrospective cohort study design was used with a large US national administrative claims database. Commercially-insured DPNP patients aged 18-64 years who initiated duloxetine or pregabalin in 2006 were selected, with the first initiation date as the index date. All selected patients had 12 months continuous enrollment in the pre- and post-index periods, and were grouped into the duloxetine or pregabalin cohort based on the index agent. The duloxetine and pregabalin cohorts were constructed via propensity score stratification with similar demographics, co-morbid medical conditions, pre-index healthcare utilization and costs, and prior treatment patterns. Medication possession ratio (MPR), proportion of patients with MPR ≥ 0.8 and healthcare costs over the 12-month post-index period were compared between cohorts.
Results: Both the duloxetine (n = 794) and pregabalin (n = 1779) cohorts had a mean age of 56 years, and 58% of female. Common co-morbid conditions among duloxetine and pregabalin patients were cardiovascular disease (82.5 vs. 82.2%), neuropathic pain other than DPNP (71.1 vs. 72.7%), osteoarthritis (39.0 vs. 41.3%), and low back pain (29.4 vs. 30.5%). More than 73% of the patients had opioid use prior to the initiation of duloxetine or pregabalin. Among patients with similar demographic, clinical and economic characteristics, and prior treatment patterns, duloxetine-treated patients had significantly higher MPR (0.34 vs. 0.13), higher proportion of patients with MPR ≥ 0.8 (15.5 vs. 0.7%), and significantly lower total healthcare costs ($34,146 vs. 34,897) over the 12-month post-index period than pregabalin-treated patients (all p < 0.05).
Conclusions: Commercially-insured DPNP patients initiating duloxetine had significantly higher medication adherence and lower healthcare costs than those initiating pregabalin.