BackgroundCommon mental disorders are the leading cause of workplace absences. The Prevail intervention programme aims to reduce stigma and to educate staff and managers about evidence-based low intensity psychological interventions for common mental disorders (depression, anxiety, stress, and distress). Prevail is innovative in taking a public health approach. It is designed to be given to all employees irrespective of their past or current mental health. Prevail was evaluated in three studies examining: (1) the acceptability of the intervention and perceived usefulness; (2) whether the intervention altered stigmatic attitudes and motivation to seek help; and (3) whether the intervention reduced sickness absence, both overall and due to mental health problems.MethodsA two-armed cluster randomised control trial (RCT) evaluated the effectiveness of Prevail. Employees (N= 1051) at a large UK government institution were randomised to an active intervention or control arm in teams identified by their managers (n= 67). Employees in the active arm received the Prevail Staff Intervention. The managers in the active arm also received the Prevail Managers Intervention. Participants’ satisfaction and analysis of the Prevail Intervention were gathered by a bespoke questionnaire. Questionnaire measures of attitudes to mental health and mental health stigma were taken 1–2 weeks prior to the intervention and approximately 4 weeks post-intervention. Data relating to sickness absence were gathered via the official records in the time period 3-month post-intervention and for the same period 12 months earlier.ResultsPrevail was evaluated highly favourably by both the staff and their managers. Prevail produced significant reductions in self-stigma and anticipated stigma due to mental health difficulties. Crucially, sickness absence was significantly reduced by the Prevail Intervention.DiscussionPrevail achieved its goals of producing a palatable and engaging intervention that altered staff’s attitudes and stigmatic beliefs related to mental health and, crucially, produced a strong reduction in work-pace absenteeism. As the Prevail programme is aimed at common mental health problems and was not specialised to this particular workforce, the study provides the evidence-base for a mental health intervention programme that could be used by many organisations across the world.Trial RegistrationISRCTN12040087. Registered 04/05/2020. 10.1186/ISRCTN12040087. A full protocol for the randomised control trial was published: Gray NS, Davies H, Snowden RJ: Reducing stigma and increasing workplace productivity due to mental health difficulties in a large government organization in the UK: a protocol for a randomised control treatment trial (RCT) of a low intensity psychological intervention and stigma reduction programme for common mental disorder (Prevail).BMC Public Health2020, 20(1):1–9.