Opioid Utilization and Health-Care Costs among Patients with Diabetic Peripheral Neuropathic Pain Treated with Duloxetine vs. Other Therapies

Objective: This retrospective cohort study assessed subsequent opioid utilization and health-care costs among patients with diabetic peripheral neuropathic pain (DPNP) who initiated duloxetine vs. other standard of care (SOC) treatments. Methods: Medical and pharmacy claims were analyzed for commercially-insured individuals aged 18–64. Two study cohorts were constructed from DPNP patients who initiated duloxetine or SOC medications (tricyclic antidepressants, venlafaxine, gabapentin, pregabalin) between March 1, 2005 and December 31, 2005. Initiation was defined as a prior 90-day period without access of the medication. The dispense date of the first initiation was denoted as the index date. Patients with opioids dispensed in the prior 90 days were excluded. Opioid utilization including total days, number of prescriptions filled, and morphine equivalent dosage was assessed for overall, long-acting, and short-acting opioids. Health-care costs and opioid use in the 12-month post-index period were examined via multivariate regression analyses. Results: Four hundred and ninety-nine DPNP patients (272 duloxetine, 227 SOC) were identified. SOC patients had higher prevalence of comorbidities and pre-index health-care costs than duloxetine patients. Controlling for cross-cohort differences, duloxetine patients were significantly less likely to use any opioids than SOC patients. Also, duloxetine patients had 20 fewer adjusted opioid supply days (largely due to the use of short-acting opioids, P