SUPPLEMENTARY MATERIALS from Effectiveness of self-help plus (SH+) in reducing anxiety and post-traumatic symptomatology among care home workers during the COVID-19 pandemic: a randomized controlled trial

This article describes a randomized controlled trial to evaluate the effectiveness of a supervised online delivery of self-help plus (SH+), during the second wave of COVID-19 contagions in Northern Italy. The SH+ is a psychological intervention developed by the World Health Organization to increase a person's ability to deal with stress. In this trial, it was tested primarily as a tool to reduce anxiety and post-traumatic symptomatology in workers of residential nursing and care homes. In order to partial out non-specific effects of the intervention, the SH+ was compared to an equally supervised and structured alternative activity. Secondarily, in view of future emergencies, the potential of SH+ as a tool to reduce perceived stress, increase subjective well-being and foster individual resilience was explored. At post-intervention, the preregistered analysis revealed no difference in self-reported anxiety and/or post-traumatic symptomatology between the group receiving the SH+ and the group engaged in an alternative activity. Some specific and positive effects of the SH+ intervention were only found on self-reported intervention effectiveness and engagement in exploratory analyses. These findings raise the question whether the previously documented effectiveness of the SH+ on self-reported symptomatology and on the prevention of psychiatric conditions could be attributed mostly to non-specific rather than specific factors connected with participant enrolment in a psychological intervention. Indeed, the effects of the SH+ had been previously compared only to the effects of not being engaged in any alternative activity (often described in the literature as ���treatment as usual������or ���enhanced treatment as usual���, when some relevant information is given to the control group as a one-off). Given the negative findings of this study, before the SH+ is implemented in clinical practice, further studies should be conducted to examine its short- and long-term beneficial effects, by means of randomized studies that employ alternative but similarly structured interventions as control conditions, aiming to minimize the confounding effect of non-specific factors.