Duloxetine and venlafaxine extended release (venlafaxine XR) are SNRIs indicated for the treatment of MDD. This study addresses whether duloxetine and venlafaxine XR are interchangeable in their patterns of use with patients who are depressed or are used more selectively based on treatment history, background characteristics, and presenting symptoms.
This was a retrospective analysis of an administrative insurance claims database. We studied patients in managed care with major depressive disorder (MDD) treated with duloxetine or venlafaxine XR. Predictors of treatment and cost were assessed using Chi-square and logistic regression analyses of demographics and past-year medication use and comorbidities.
Patients with MDD treated with duloxetine (n = 9,641) versus venlafaxine XR (n = 8,514) tended to be older, slightly more likely to be female, and treated by a psychiatrist (P < 0.0001). In the prior year, more duloxetine patients (vs. venlafaxine XR) received ≥3 unique antidepressants (20.8% vs. 16.6%), ≥3 unique pain medications (25.5% vs. 15.6%), and had ≥8 unique diagnosed comorbid medical and psychiatric conditions (38.6% vs. 29.1%). The prior 6-month total health care costs were $1,731 higher for duloxetine than for venlafaxine XR and declined for both medications in the 6 months after treatment began. Logistic regression analysis revealed that 61% of duloxetine patients and 61% of venlafaxine XR patients were predictable from prior patient and treatment factors.
Patients with MDD treated with duloxetine tended to have a more complex and costly antecedent clinical presentation compared with venlafaxine XR patients, suggesting that physicians do not use the medications interchangeably.