Adaptation and preliminary validation of the Montgomery-Åsberg Depression Rating Scale (MADRS) using the Structured Interview Guide (SIGMA) for European Portuguese

The Montgomery-Åsberg Depression Rating Scale (MADRS) is considered one of the gold-standard measures to assess depression severity. To standardise the MADRS administration, a structured interview was developed (SIGMA). This study aims to translate and validate the SIGMA for European Portuguese. Twenty patients (80% women) were interviewed by ten dyads of raters (trained clinical psychologists and psychiatrists) using the European Portuguese version of the MADRS and its structured interview SIGMA. There was no significant difference in the total MADRS score between raters (interviewers and observers). The intraclass correlation for the total score between raters using the SIGMA was excellent (r = .98; p < .001). All items had excellent to good item-level intraclass correlation, and the internal consistency by rater role was good. The European Portuguese version of the SIGMA showed good preliminary psychometric properties (reliability and internal consistency). Our results suggest that the SIGMA is a useful and robust interview guide for assessing the ten depression symptoms in the MADRS, regardless of the rater clinical background.