Measuring Response to Adjunctive Therapy Among Individuals with Major Depressive Disorder

Area of Science:

• Psychiatry
• Clinical Psychology
• Pharmacology

Background:

• Major depressive disorder (MDD) frequently shows an inadequate response to first-line antidepressant therapy (ADT).
• The effectiveness of adjunctive therapies for MDD remains less understood, particularly in real-world settings.
• Patient monitoring for treatment response is crucial for optimizing care.

Purpose of the Study:

• To evaluate the response rates to adjunctive pharmacotherapy, psychotherapy, or both in patients with MDD receiving ongoing ADT.
• To identify factors associated with symptom improvement using the Patient Health Questionnaire-9 (PHQ-9) score.
• To assess the adequacy of treatment response monitoring in a large cohort.

Main Methods:

• Retrospective analysis of medical and pharmacy claims data for individuals with MDD initiating adjunctive therapy between July 2014 and December 2018.
• Symptom severity was assessed using PHQ-9 scores at baseline and 12-month follow-up.
• Multivariate logistic regression was employed to determine predictors of improved symptom severity.

Main Results:

• The majority of participants (81.8%) received adjunctive pharmacotherapy, 12.7% psychotherapy, and 5.5% both.
• Only 30.2% of the cohort had both baseline and follow-up PHQ-9 scores available for analysis.
• Among patients with available PHQ-9 scores, a significant proportion (36.7% with mild-to-severe baseline scores, 28.1% with moderate-to-severe baseline scores) showed no improvement or worsening of MDD symptoms.

Conclusions:

• Inadequate monitoring of treatment response, evidenced by low rates of follow-up PHQ-9 completion, is prevalent in patients with moderate-to-severe MDD.
• A substantial number of patients receiving adjunctive therapy continue to experience significant depressive symptoms.
• Further research is needed to explore alternative treatment modalities and enhance the systematic use of tools like the PHQ-9 for monitoring treatment efficacy in MDD.