How to distinguish promotion, prevention, and treatment trials in public mental health: development and validation of the VErona-LUgano Tool (VELUT)

Background: Promoting mental health, preventing mental disorders and providing effective treatments are public health priorities. Randomized controlled trials (RCTs) frequently evaluate mental health and psychosocial support interventions to achieve one or more of these objectives. Distinguishing between RCTs focused on mental health promotion, prevention or treatment remains conceptually and methodologically challenging. No standardized tool exists to position RCTs along a promotion-to-treatment continuum in mental health. We aimed to develop and validate the VErona-LUgano Tool (VELUT) for distinguishing RCTs along the promotion-to-treatment continuum. Methods: An interdisciplinary tool development group (TDG) was established. The Population, Intervention, Comparison and Outcome framework was used to define key constructs. Items in the tool were devised, categorized and reduced through qualitative and quantitative methods. Finally, we performed a preliminary validation of the VELUT applying item response theory (IRT) using data from 180 RCTs. Results: The TDG generated 33 items for the initial version of the VELUT, reduced to 16 through review, cognitive interviews and psychometric analysis. Analyses of 180 RCTs using the 16-item tool showed high internal consistency (α = 0.94) and unidimensionality. Following item reduction and IRT, a final 8-item version was retained, and IRT models confirmed strong item discrimination for the 8 items and high scale reliability (marginal reliability >0.90 across most of the range of the scale), good response distribution, item performance and alignment with the Institute of Medicine (IOM) promotion-to-treatment continuum. Conclusions: The VELUT addresses methodological gaps in global mental health research by helping to position RCTs of MHPSS interventions along the IOM promotion-to-treatment continuum.