Table 1

 Criteria for occupational health intervention studies

Intervention studiesAny kind of active manipulation of the environment, behaviour, or disease
A1RCT or cluster RCT
A2Controlled trial: before/after measurement with concurrent control group
A3Time series: three outcome measurements before and three after the intervention
A4Before/after comparison without control group
A5Quality of care studies, comparison of outcome among different levels of intervention, comparison with arbitrary controls
Occupational health studies Intervention aimed to improve workers’ health
B1Intervention to remove/eliminate adverse exposure
B2Intervention to influence healthy and safe behaviour of workers
B3Intervention to influence occupational disease or work related symptoms or signs
B4Intervention to prevent occupational disability, maintain working ability, reduce sickness absence, increase return to work
B5Intervention to reduce injuries and occupational accidents
B6Intervention to increase the quality of occupational health services or the quality of occupational health professionals