Patient Response Trajectories in Major Depressive Disorder.

Objective: To investigate whether the efficacy of antidepressants can be understood in terms of patient response-trajectory classes.

Experimental design: Patient-level data were analysed from 1357 adults with MDD randomised to either escitalopram 20 mg/day (n = 676) or placebo (n = 681) in five 8-week randomised placebo-controlled trials. Growth mixture models (GMMs) were used to identify the response trajectories; longitudinal latent class analysis (LLCA) was used to corroborate the findings.

Principal observations: Three classes of response were identified for escitalopram and placebo based on the trajectory of the patients' Montgomery-Åsberg Depression Rating Scale (MADRS) total scores during treatment. All three classes had similar mean baseline MADRS scores, but the change from baseline after 8 weeks differed: -4.2 MADRS points for non-responders, -18.4 MADRS points for slow responders, and -26.7 points for fast responders. The proportions of non-responders, slow responders and fast responders were 53%, 38% and 9%, respectively, with placebo and 27%, 58% and 14%, respectively, with escitalopram. Receiver operating curve analysis showed that a cut-off of ≥43% improvement from baseline to week 2 predicted fast responders, and a cut-off of ≥28% improvement from baseline to week 4 predicted responders (fast or slow). There were no clinically useful differences at baseline that predicted the trajectory class to which a patient would belong.

Conclusions: The presence of fast-, slow- and non-responder classes has a clear clinical relevance for guiding treatment decisions; individual patients can be classified by the change in their MADRS score from baseline at 2 or 4 weeks.