Randomized Controlled Trial of Acceptance and Commitment Therapy and a Workplace Intervention for Sickness Absence Due to Mental Disorders

Mental disorders contribute to high rates of sickness absence (SA) and impaired work functioning. The aim of the present study was to evaluate the efficacy of 3 interventions targeting SA of workers. Participants (n = 352; 78.4% females) of working age with current employment, and SA due to depression, anxiety disorders, or exhaustion disorder, were recruited to the study and randomized to (a) acceptance and commitment therapy (ACT), (b) a workplace dialogue intervention (WDI), (c) a combination of ACT and WDI, or (d) treatment as usual (TAU). For SA days, there was a significant interaction effect for the follow-up period, in which ACT + WDI generated more SA compared with TAU. When diagnostic group was included as a moderator, participants with exhaustion disorder had less SA days in the WDI group compared with TAU. For symptoms of depression, anxiety, and stress-related ill health, there were significant interaction effects for ACT and ACT + WDI, when compared with TAU, from pre- to postmeasurement (small to moderate between-groups effect sizes). Within-group effect sizes pre- to postmeasurement (Cohen's d) ranged from .55 to 1.17 (ACT), .40 to .94 (WDI), .26 to 1.13 (ACT + WI), and -.06 to .70 (TAU). There were no differences between groups during follow-up for symptoms.