Intervention targeted at physicians' treatment of musculoskeletal disorders and sickness certification: an interrupted time series analysis

Objective: An intervention was carried out at the occupational healthcare services (OHS) of the City of Helsinki beginning in 2016. We investigated the association between the intervention and employee sick leaves using interrupted time series analysis.

Design: Register-based cohort study with a quasi-experimental study design.

Setting: Employees of the City of Helsinki.

Participants: We analysed individual-level register-based data on all employees who were employed by the city for any length of time between 2013 and 2018 (a total 86 970 employees and 3 014 075 sick leave days). Sick leave days and periods that were OHS-based constituted the intervention time series and the rest of the sick leave days and periods contributed to the comparison time series.

Intervention: Recommendations provided to physicians on managing pain and prescribing sick leave for low back, shoulder and elbow pain.

Outcome measures: Number of sick leave days per month and sick leave periods per year.

Results: For all sick leave days prescribed at OHS, there was no immediate change in sick leave days, whereas a gradual change showing decreasing number of OHS-based sick leave days was detected. On average, the intervention was estimated to have saved 2.5 sick leave days per year per employee. For other sick leave days, there was an immediate increase in the level of sick leave days after the intervention and a subsequent gradual trend showing decreasing number of sick leave days.

Conclusions: The intervention may have reduced employee sick leaves and therefore it is possible that it had led to direct cost savings. However, further evidence for causal inferences is needed.