Dosing Patterns for Duloxetine and Predictors of High-Dose Prescriptions in Patients With Major Depressive Disorder: Analysis from a United States Third-Party Payer Perspective

Abstract

Background Major depressive disorder (MDD) is a common illness that affects ∼7% of adults in the United States each year. Duloxetine is a dual reuptake inhibitor of serotonin and norepinephrine that has demonstrated efficacy and tolerability in the treatment of MDD. Objective The purpose of our study was to examine dosing patterns and pretreatment predictors of high-dose duloxetine therapy for patients with MDD in the usual clinical setting. Methods Data were from 6132 commercially insured patients with MDD initiated on duloxetine during 2005 and 2006. Patients had no duloxetine use in the previous 6 months and had continuous enrollment in a health plan for the 12 months immediately preceding and following initiation. Dosing patterns and predictors of high-dose therapy with duloxetine were examined. Results Initial doses of duloxetine were <60 mg/d, 60 mg/d, 90 mg/d, and ≥120 mg/d for 32.4%, 60.9%, 3.1%, and 3.5% of patients, respectively. Maximum daily doses were <60 mg, 60 mg, 90 mg, and ≥120 mg for 16.3%, 59.3%, 11.0%, and 13.3% of patients, respectively. Patients treated with >60 mg/d for at least 2 months were older, were more likely to have been treated by a psychiatrist, had greater comorbidity, and had used more health care resources and psychotropic and pain medications in the previous year. The following factors were independently associated with doses of >60 mg/d: older age (odds ratio [OR] = 1.33–1.46); comorbid neuropathic pain (OR = 1.88); fibromyalgia (OR = 1.36); dysthymic disorder (OR = 1.24); prior injury/poisoning (OR = 1.19); physician specialty (psychiatrist, OR = 1.55); and prior use of psychostimulants (OR = 1.26), benzodiazepines (OR = 1.19), venlafaxine (OR = 1.35), or atypical antipsychotics (OR = 1.35). Conclusions Most of the commercially insured patients in this dataset were initiated and maintained on a duloxetine dose of 60 mg/d. Although the data are limited in their generalizability, the characteristics associated with higher dose therapy describe a complex group of patients who may require more intensive drug treatment and monitoring.