Predictors of time until return to work and duration of sickness absence in sick-listed precarious workers with common mental disorders: a secondary data-analysis of two trials and one cohort study

Background: Common mental disorders (CMD) are highly prevalent among sick-listed precarious workers and often lead to long-term sickness-absence, work disability and unemployment. This study aimed to identify predictors of a longer time until return to work (RTW) and prolonged duration of sickness absence in sick-listed precarious workers with CMD. Methods: We conducted a secondary Cox regression analysis using existing data from two Dutch randomized controlled trials and one cohort study among sick-listed precarious workers with CMD (N = 681). Age, gender, baseline employment status, study allocation, severity of psychological symptoms and RTW self-efficacy were evaluated for their predictive value on time until sustainable (≥ 28 days) RTW and duration of sickness absence during 12-month follow-up. In this study, time until sustainable RTW and duration of sickness absence are distinct dependent variables, because they are not mutually exclusive. Results: Age above 50 years (HR 0.57, 95% CI 0.39–0.82), severe psychological symptoms (HR 0.64, 95% CI 0.43–0.93), unemployment (HR 0.19 95% CI 0.11–0.33) and loss of employment contract during sickness absence (HR 0.25, 95% CI 0.14–0.47) were predictive of a longer time until RTW. Male gender (HR 0.77, 95% CI 0.62–0.97), severe psychological symptoms (HR 0.64, 95% CI 0.46–0.87), unemployment (HR 0.47, 95% CI 0.27–0.84) and loss of employment contract (HR 0.48, 95% CI 0.26–0.90) predicted a prolonged duration of sickness absence. Conclusions: Unemployment at the moment of sick-listing, loss of employment contract during sickness absence, and severe psychological symptoms are predictors of both a longer time until RTW and prolonged duration of sickness absence among sick-listed precarious workers with CMD. This knowledge assists occupational health and mental health professionals in the early identification of workers at risk of long-term sickness absence, enabling them to arrange targeted occupational rehabilitation support and mental health care. Trial registration: The included randomized controlled trials were prospectively registered in the Dutch national trial register under NTR4190 (September 27, 2013) and NTR3563 (August 7, 2012).