The work ability continuum : Epidemiological studies of factors promoting sustainable work ability

Sammanfattning: For the individual, the workplace and society, there would be considerable gains if the number of people suffering from physical and mental disorders could be reduced. The overall aim of this thesis was to identify determinants for future work ability among gainfully employed women and men, with special reference to promotive factors at work. Work ability is in this thesis defined as the ability to work with respect to demands at work on health and physical and mental resources, while impaired work ability is expressed in terms of sick leave rates. The reasons to study promoting factors were threefold: firstly, to find alternatives to traditional risk prevention. Secondly, if work ability is regarded as a continuum, promotive measures could bring individuals closer to the positive end-point and further away from the breaking point of getting sick-listed long-term. Thirdly, the scientific basis for workplace health promotion is limited. The thesis comprises four prospective studies based on two different Swedish cohorts, for which data were collected 1999-2004. Studies I, III and IV are based on a strategic sample of 9 000 employees in the public sector aged 19 65 years, of which 81% answered a baseline questionnaire and were followed up for 1½ 4 years by means of questionnaires and register data on sick leave. Study II is based on a random sample of 12 000 persons from the general population aged 35, 45 and 55 years, of which 65% answered a baseline questionnaire and were followed up for 1 year by means of register data. In studies I III several factors in private and working life acted as determinants of future work ability. Some of these determinants were associated solely with excellent work ability, some solely with poor work ability and others with both. Most of the identified lifestyle- and work-related determinants are amenable to influence in order to promote sustainable work ability. Such determinants associated with excellent work ability (no sick leave) were physical leisure exercise, content with number of working hours, good work postures, high role clarity, low psychological demands and positive feed-back from superior. Determinants associated with retained work ability (?14 days of sick leave) were being recuperated, in the mood for work and physical non-strenuous work. Determinants associated with poor work ability (sick leave long-term, >28 days) were obesity, not being recuperated, not in the mood for work, bullying, physical and mental demands at work higher than own capacity, high psychological demands and low decision latitude. No significant differences between the sexes were found. In study IV were five single- and multi-question instruments for self-assessment compared with regard to prediction of future work ability. These instruments showed similar power to predict; also, they were better at discriminating for poor than for excellent work ability and discriminated poor work ability somewhat better for men than for women. In conclusion, in this thesis work ability was associated with a number of factors both in private and in working life, somewhat different at the two end-points excellent and poor work ability. As most of the identified determinants are amenable to influence, this opens up for possible interventions. Single-item instruments for self-rated health/work ability can be used for purposes such as screening to identify risk groups for impaired work ability. Further studies are needed to establish whether an approach in terms of promoting work ability is practicable for sustainable working life.