Early symptom improvement and other clinical predictors of response to repetitive transcranial magnetic stimulation for depression

Abstract

BackgroundRepetitive transcranial magnetic stimulation (rTMS) is a rapidly emerging treatment for depression, but outcome prediction is still a challenge. This study aimed to identify predictors of response to rTMS among baseline clinical factors and early symptomatic improvements. MethodsThis cohort study comprised 136 patients with a unipolar or bipolar depressive episode referred for clinical intermittent theta-burst stimulation or right-sided 1 Hz rTMS at the Uppsala Brain Stimulation Unit. The co-primary outcomes used for logistic regression were response, defined as ≥50 % reduction of Montgomery and Åsberg Depression Rating Scale Self-assessment (MADRS-S) total score, and 1–2 points on the Clinical Global Impression Improvement (CGI-I) scale. Early improvement was defined as ≥20 % reduction in the MADRS-S total score, or ≥ 1 point reduction in each MADRS-S item, after two weeks of treatment. ResultsThe response rates were 21 % for MADRS-S and 45 % for CGI-I. A depressive episode >24 months had lower odds for MADRS-S response compared to ≤12 months. Early improvement of the MADRS-S total score predicted CGI-I response (95 % CI = 1.35–9.47, p = 0.011), Initiative6 predicted MADRS-S response (95 % CI = 1.08–9.05, p = 0.035), and Emotional involvement7 predicted CGI-I response (95 % CI = 1.03–8.66, p = 0.044). LimitationsNo adjustment for concurrent medication. ConclusionsA depressive episode ≤12 months and early improvement in overall depressive symptoms, as well as the individual items, Initiative6 and Emotional involvement7, predicted subsequent rTMS response in a naturalistic sample of depressed patients. This could facilitate the early identification of patients who will benefit from further rTMS sessions.