Factors associated with duloxetine treatment among patients with major depressive disorder in Veterans Health Administration: a retrospective study

Abstract

Objective:

To examine the predictors of duloxetine monotherapy versus other antidepressants among patients with major depressive disorder (MDD) in the Veterans Health Administration (VHA).

Methods:

Patients initiating duloxetine or other antidepressants between October 1, 2005 and October 1, 2007 were extracted from the Veterans Integrated Service Network (VISN)16 data warehouse. All patients included had at least one MDD diagnosis prior to the initiation of duloxetine or other antidepressants. Patients with prior diabetes, schizophrenia, or bipolar disorder diagnosis were excluded. Logistic regression was used to identify predictors of duloxetine initiation versus other antidepressants.

Results:

Among 448 duloxetine and 11,629 non-duloxetine patients identified, more duloxetine-treated patients had pre-index opioid use (62.72% vs. 22.03%), substance abuse (36.38% vs. 27.72%), or reported pain (60.94% vs. 46.29%) than non-duloxetine treated patients (all p-values <0.001). Prior users of long-acting (odds ratio [OR] = 8.98, 95% confidence interval [CI]: 6.95, 11.60) and short-acting (OR = 3.32, 95% CI: 2.60, 4.23) opioids were more likely to initiate duloxetine than those not. Patients who experienced moderate or severe pain or substance abuse were also more likely to initiate duloxetine (OR = 1.43, 95% CI: 1.07, 1.90; 1.50, 95% CI: 1.16, 1.92; 1.41, 95% CI: 1.14, 1.75; respectively). Other significant predictors included being female, white, having non-VHA insurance, prior hospitalization, emergency room visits, dyslipidemia and hypertension (all p-values <0.05).

Key Limitations:

It is a retrospective analysis among VHA patients of a single VISN.

Conclusion:

Among the VHA patients with MDD, prior opioid use was the strongest predictor of duloxetine initiation, followed by moderate-to-severe pain and substance abuse diagnosis.

Key words:

• Antidepressant
• Major depressive disorder
• Retrospective study
• Veterans

Transparency

Declaration of funding

The funding of this study was provided by Eli Lilly and Company. The statements contained in this paper are solely those of the authors and no endorsement by Eli Lilly and Company should be inferred or implied. We wish to thank the Veterans Integrated Service Networks (VISN) 16 data warehouse for the de-identified data set. This study was presented as a poster at the 12th Scientific Sessions of the European International Society for Pharmacoeconomics and Outcomes Research, Paris, October 2009. The contents of this manuscript do not represent the views of the Department of Veterans Affairs or the United States Government.

Declaration of financial/other relationships

Shi and Liu are WOC employees/investigators for the Southeast Louisiana Veterans Health Care System. Shi has received research support (to Tulane) from the American Diabetes Association, Eli Lilly and Company, Takeda, and Blue Cross Blue Shield of Louisiana. Zhao is an employee of Eli Lilly and Company, and owns company stocks. Liu, a certified advanced programmer for SAS®9, primarily performed the data analysis. All authors participated in data interpretation. Shi, Campbell and Zhao wrote the manuscript with assistance from Liu. All authors contributed to the revisions of the manuscript.

Peer reviewers may receive honoraria from CMRO for their review work. The peer reviewers have disclosed no relevant financial relationships.

Acknowledgements

No assistance in the preparation of this article is to be declared.