New episodes of musculoskeletal conditions among employed people in Norway, sickness certification and return to work: a multiregister-based cohort study from primary care.

Objectives: To identify new cases of musculoskeletal (MSK) disorders among employed people presenting in Norwegian primary care in 2012, frequency of sickness certification and length of sick leave. To identify patient-, diagnosis- and GP-related predictors of sickness certification, prolonged sick leave and return to work (RTW).

Methods: An observational multiregister-based cohort study covering all employed persons in Norway(1 176 681 women and 1 330 082 men) based on claims data from all regular GPs merged with individual sociodemographic data from public registers was performed. Participants were employed patients without any GP consultation during the previous 3 months who consulted a GP with a diagnosis of a MSK condition. Those not on sick leave and with a known GP affiliation were included in the analyses. Outcomes were incidence, proportion sickness certified and proportion on sick leave after 16 days, according to the diagnosis, ORs with 95% CIs for sickness certified and for sick leave exceeding 16 days and HRs with 95% CIs for RTW.

Results: One-year incidence of MSK episodes was 159/1000 among employed women and 156/1000 among employed men. 27.1% of the women and 28.2% of the men were sickness certified in the initial consultation. After 16 days, 10.5% of women and 9.9% of men were still on sick leave. Upper limb problems were most frequent. After adjustments, medium/high education predicted a lower risk of absence from work due to sickness and rapid RTW after 16 days. Back pain, fractures and female gender carried a higher risk of sickness certification but faster RTW. Older age was associated with less initial certification, more sick leave exceeding 16 days and slower RTW. Male patients with male GPs had a lower risk of sickness absence, which was similar to patients with GPs born in Norway and GPs with many patients. After 16 days, GP variables had no effect on RTW.

Conclusion: Upper limb problems and GPs as stakeholders in 'the inclusive workplace' strategy need more attention.