Sick at work--a risk factor for long-term sickness absence at a later date?

BACKGROUND: Little is known about the long-term consequences of sickness presence (ie, going to work despite ill-health), although one study suggests an association with coronary heart disease. This study examined the effect of sickness presence on future long-term sickness absence.
METHODS: Information from a random sample of 11 838 members of the Danish core workforce was collected from questionnaires, containing questions about work, family and attitudes towards sickness absence. Information on prospective sickness absence spells of at least 2 weeks was derived from an official register during a follow-up period of 1.5 years.
RESULTS: Sickness presence is associated with long-term sickness absence of at least 2 weeks' duration as well as with spells lasting at least 2 months. Participants who had gone to work ill more than six times in the year prior to baseline had a 74% higher risk of becoming sick-listed for more than 2 months, even when controlling for a wide range of potential confounders as well as baseline health status and previous long-term sickness absence. The association was consistent for most subgroups of employees reporting various symptoms, but either disappeared or became insignificant when analysing subgroups of employees with specific chronic diseases.
CONCLUSIONS: Going to work ill repeatedly is associated with long-term sickness absence at a later date. For this reason, researchers and policy-makers should consider this phenomenon more carefully when planning future studies of sickness absence or when laying out new policies.