Concurrent trajectories of part-time work and sickness absence: a longitudinal cohort study over 11 years among shift working hospital employees

Objectives To investigate the concurrent changes in part-time work and sickness absence (SA) in healthcare. Another aim was to investigate the role of age and sex on different concurrent trajectory groups.Design Prospective cohort study.Setting Public hospital districts (n=10) and cities (n=11) in Finland.Participants Payroll-based objective working hour data of the healthcare sector in Finland for 28 969 employees in 2008-2019 were used. The final sample included those working shifts with 3 consecutive years of data and without baseline (>= 14 days) SA.Primary outcomes Part-time work (yes or no) and months of SA.Measures Group-based trajectory modelling to identify concurrent changes in part-time work, and months of SA while controlling the time-variant amount of night work and multinomial regression models for relative risk (RR) with 95% CIs were used.Results Four-group trajectory model was the best solution: group 1 (61.2%) with full-time work and no SA, group 2 (16.9%) with slowly increasing probability of part-time work and low but mildly increasing SA, group 3 (17.6%) with increasing part-time work and no SA, and group 4 (4.3%) with fluctuating, increasing part-time work and highest and increasing levels of SA. Men had a lower (RR 0.49-0.75) and older age groups had a higher likelihood (RRs 1.32-3.79) of belonging to trajectory groups 2-4.Conclusions Most of the sample were in the trajectory group with full-time work and no SA. The probability of part-time work increased over time, linked with concurrent low increase or no SA. A minor group of employees had both an increased probability of part-time work and SA. Part-time work and other solutions might merit attention to promote sustainable working life among healthcare employees.