Effectiveness of IPT-G in Major Depression

Patients presenting a current unipolar depression episode (BDI-II \> 18) without response to 2 adequate antidepressants trials (optimized by dose and time) will be randomly allocated to two arms: a) Treatment-as-usual (TAU) arm: antidepressant + Clinical management; b) Add-on strategy arm: 14 sessions of IPT-Group added to TAU. IPT-Group will be delivered following manualized guidelines (WHO, 2016 and Stuart et al. 2012). The choice of antidepressants for TAU will be based on the Canadian Network for Mood and Anxiety Treatments (CANMAT) recommendations. Clinical management will follow the National Institute for Mental Health (NIMH) recommendations for clinical management. Depression episode will be diagnosed using the Mini International Neuropsychiatric Interview (MINI-PLUS). The following variables will be evaluated at baseline and the end of the add-on intervention in both arms of the study: a) depression symptoms- Beck Depression Inventory (BDI-II; b) anxiety symptoms - Beck Anxiety Inventory (BAI); c) quality of life- World Health Organization Quality of life Instrument short version (WHOQOL-bref); d) social support- Medical Outcomes Study Social. Support Survey (MOS-SSS); e) resilience- The Brief Resilience Scale (BRS); f) attachment- The Adult Attachment Scale (AAS-R) Depression symptoms are the primary outcome. Anxiety symptoms and quality of life the secondary outcomes. Social support, resilience, and attachment will be considered as both secondary outcome and mediator or moderators in a multivariate model. The database will be built using REDCap (Research Electronic Data Capture). Sample size estimation to detect a 5-point difference between the groups with a standard deviation of 6, considering α = 0,05 and power of 90%, suggests a 64 subjects sample. With the estimation of a loss of 25% of the sample during the study, 80 patients will be included (40 in each arm). A trained psychotherapist will conduct five IPT-G groups with eight patients in each group. Study design and analysis will use Intention-to-treat analysis. For quantitative variables testing, student-T test t (normal distribution) or Mann Whitney (absence of normal distribution) will be used with a 5% level of significance. Categorical variables will be tested using the Chi-square with exact Fischer test with a 5% level of significance. Hierarchical linear regression will be used to determine the variables that could predict a reduction in the depression scores of the BDI-II. All analysis will be performed using the Statistical Package for the Social Sciences (SPSS) version 20.0.