Correlates of residual fatigue in patients with major depressive disorder: The role of psychotropic medication

Objective: Fatigue is not only a core symptom of major depressive disorder (MDD), but also a common residual symptom. We determined the sociodemographic, clinical, and pharmacologic factors that were associated with fatigue in patients with remission or partial remission of MDD. Methods: Data was derived from a randomized controlled trial of acupuncture in 137 MDD patients with residual symptoms. Fatigue was measured by Multidimensional Fatigue Inventory (MFI-20). Self-report and clinician-rated scales were used to assess psychopathology. 17-item Hamilton Depression Rating Scale (HDRS₁₇) score≤7 denoted MDD remission. Results: Participants' average HDRS₁₇ score was 10.5; 29.2% were in remission. The average MFI-20 score was 71.8; 83.2% had severe fatigue, defined as MFI-20 score≥60. Fifty-two of 137 participants (38%) were using sedating psychotropic medications. Antidepressant dosage ranged from 1-90 mg fluoxetine equivalent and sedatives/hypnotics from 1-60 mg diazepam equivalent. There were significant correlations between MFI-20 score and HDRS₁₇ depression and anxiety subscores, Hospital Anxiety and Depression Scale (HADS) depression and anxiety subscores, and Pain Catastrophizing Scale score, but insomnia and daytime sleepiness, sociodemographics, current medical conditions, and psychotropic medication use were not significant correlates. Upon multiple regression, HADS and HDRS₁₇ depression scores independently predicted MFI-20 score. In remission and partial remission subgroups, HADS depression score was an independent predictor. Limitation: Participants were recruited from specialty psychiatric units; hence the findings may not be applicable in non-specialized settings. Conclusion: Fatigue was predicted by depression severity in remitted or partially remitted MDD. Psychotropic medication and higher dosage were not associated with greater fatigue.