Factors associated with pain medication selection among patients diagnosed with diabetic peripheral neuropathic pain:...

To assess the demographic and clinical characteristics associated with initiation of duloxetine therapy compared with other pharmacologic therapies for treatment of diabetic peripheral neuropathic pain (DPNP).

This study used administrative claims databases for commercially-insured individuals aged 18-64 years to examine factors associated with treatment among DPNP patients who initiated duloxetine versus tricyclic antidepressants (TCAs), venlafaxine, gabapentin, pregabalin, or opioids between 7/1/2005 and 12/31/2007. Treatment initiation was defined as no pill coverage of the same medication over the previous 90 days. Multiple logistic regression models were estimated to assess factors associated with initiating duloxetine versus each of the other DPNP therapies.

The study included 11,060 DPNP patients with average age of 55 years old. Cardiovascular disease (63-70%), cerebrovascular/peripheral vascular disease (26-33%), low back pain (24-39%), and osteoarthritis (17-26%) were the most common diabetes- and pain-related comorbidities. Controlling for demographic and clinical characteristics, patients who received duloxetine or pregabalin in the prior 12-month period were more likely to initiate duloxetine. Patients from other DPNP treatment cohorts, except for those in the pregabalin cohort, were more likely to re-initiate the same prior therapy than begin treatment with duloxetine (all p<0.05). A history of anxiety disorder was significantly associated with initiation of all DPNP treatments other than duloxetine (all p<0.05), except for TCAs. Patients with low back pain were more likely to initiate duloxetine than TCAs or venlafaxine, but less likely to initiate duloxetine than pregabalin or opioids. Patients with infections related to diabetes were less likely to initiate duloxetine than venlafaxine, gabapentin, or opioids.

Because a retrospective administrative claims database was used, this study is subject to selection bias due to unobservable confounders, inability to measure prescriber preferences or characteristics or disease severity.

Among commercially-insured DPNP patients, those with prior use of duloxetine or pregabalin were more likely to initiate duloxetine than other treatments. The presence of select comorbidities was also associated with specific medication initiation.