The Effectiveness and Cost-effectiveness of Health Advice and Occupational Health Intervention on Work Ability. Two Randomised Trials.

The study design is a longitudinal cohort study with two embedded randomised trials. The risk of sickness absence is classified on the basis of self-administered questionnaires, on the basis of a priori defined cut-off limits. Two randomised trials are performed in the subgroups of 'High Risk´ and 'Increased Risk´ of sickness absence. The study is performed within one corporation in Finland. All employees with permanent job and age between 18 and 60 years are invited to participate.

The worker's own occupational nurses and physicians execute the occupational health program for workers at 'High Risk´ for sickness absence. The employees in the "High Risk" intervention group receive a personal feedback of their health survey results in a letter, in which they are also invited to a consultation at the OHS. The main purpose of the consultation, during which the individual findings of the health survey are available for the OHS professionals, is the construction of an action plan, and if appropriate, referral to a medical specialist, or psychologist. The employees in the 'High Risk´ control group receive care as usual.

The intervention for workers at 'Increased Risk´ for sickness absence is executed as medical counselling over the telephone. The employees in the 'Increased Risk´ intervention group receive a personal feedback of their questionnaire results in a letter, in which they were also invited to call the phone advice centre in order to receive medical advice. The employees in the 'Increased Risk´ control group receive care as usual.

Sickness absence data is obtained from the employer's records, the baseline covering the one-year period before the intervention and the follow-up covering the one-year period after the intervention. Sickness absences are obtained without medical diagnoses. The study participants also fill in a health questionnaire including, among other questions, healthcare utilization variables at the one-year follow-up.

We will carry out an intention to treat analysis. We will use analysis of covariance (ANCOVA) to analyse sickness absence outcomes at 12 months, with corresponding baseline values and risk / treatment group as covariates. Economic evaluation will be performed alongside the randomised controlled trial within the 'High Risk´ group.