The relationship between symptom relief and functional improvement during acute fluoxetine treatment for patients with major depressive disorder

•Depressive symptoms showed improvement sooner than functioning.•Symptom relief did not predict subsequent functional improvement.•Functioning should be regarded as a distinctive domain of depression.

BackgroundThe purpose of this study was to compare the rate of symptom relief to functional improvement and examine the relationships between symptom relief and functional improvement during the acute phase of treatment.MethodsA total of 131 acutely ill inpatients with major depressive disorder were enrolled to receive 20 mg of fluoxetine daily for 6 weeks. Symptom severity, using the 17-item Hamilton Depression Rating Scale (HAMD-17), and functioning, using the Modified Work and Social Adjustment Scale (MWSAS), were measured regularly. The outcome measures were the HAMD-17 score and MWSAS score at weeks 1, 2, 3, 4, and 6. We compared the effect size and the reduction rate of HAMD-17 to those of MWSAS at week 1, 2, 3, 4, and 6. Structural equation modeling was used to examine relationships among the study variables.ResultsOf the 131 participants, 126 had at least one post-baseline assessment at week 1 and were included in the analysis. The HAMD-17 had a larger effect size and reduction rate than the MWSAS at weeks 1, 2, 3, 4, and 6. Parsimonious model satisfied all indices of goodness-of-fit (Chi-Square/df=1.479, TLI=0.978, CFI=0.986, RMSEA=0.062) and had all paths with significant path coefficients. MWSAS at week 0 predicted HAMD-17 at week 1.LimitationThis was an open-labeled study with small sample size.ConclusionDepressive symptoms improved more quickly than functioning during the acute phase of treatment. Depressive symptoms and functional impairment are distinct domains, and should be assessed independently.