Background Privatisations of public sector organisations are not uncommon, and some studies suggest that such organisational changes may adversely affect employee health. In this study, we examined whether transfer of work from public sector hospital units to commercial enterprises, without major staff reductions, was associated with an increased risk of long-term sickness absence among employees.

Methods A cohort study of 962 employees from four public hospital laboratory and radiology units in three hospitals which were privatised during the follow-up and 1832 employees from similar units without such organisational changes. Records of new long-term sick leaves (>90 days) were obtained from national health registers and were linked to the data. Mean follow-up was 9.2 years.

Results Age- and sex-adjusted HR for long-term sickness absence after privatisation was 0.83 (95% CI 0.68 to 1.00) among employees whose work unit underwent a change from a public organisation to a commercial enterprise compared with employees in unchanged work units. Further adjustments for occupation, socioeconomic status, type of job contract, size of residence and sick leaves before privatisation had little impact on the observed association. A sensitivity analysis with harmonised occupations across the two groups replicated the finding (multivariable adjusted HR 0.92 (0.70–1.20)).

Conclusions In this study, transfer of work from public organisation to commercial enterprise did not increase the risk of long-term sickness absence among employees.