Staff who repeatedly drag themselves into work when sick are much more likely to take long-term sick leave, Danish researchers say.

Going to work when ill is sometimes known as "presenteeism."

Previous research on British civil servants suggested that people in poor health who don't take sick leave had double the risk of heart problems compared with their colleagues who took moderate amounts of sick leave, but little else is known about the long-term effects of presenteeism.

In the May online issue of the Journal of Epidemiology and Community Health, researchers looked at data from a random sample of 11,838 Danes who were asked how many times they had to work ill when it would have been reasonable to stay at home.

Participants were then followed for another 18 months, and their answers were matched with official records of sick leaves.

The eight per cent of people who had gone to work ill more than six times a year had a 74 per cent higher risk of needing two months off compared with their co-workers, who said they never or rarely went to work sick, after taking into account previous bouts of lengthy absence and health conditions.

Coping mechanism

Short periods off sick may allow workers to cope better with the stresses of a demanding job, study authors C.D. Hansen and J.H. Andersen of the department of occupational medicine at Herning Hospital in Denmark said.

"If short-term SA [sickness absence or sick leave] indeed serves as a coping mechanism and a way for employees to rest and recuperate from high job demands, this perspective should be discussed more openly than it is today and possibly implemented into future SA policies," they concluded in the study.

"This could be done by urging employers to monitor their employee’s health instead of only their levels of SA."

It's also possible that some people just got ill more often. If these people were reluctant to take sick leave every time, they may have struggled into work more often and taken longer periods off work.

Another possibility is that people who go to work when sick generally pay less attention to their health and so are more likely to get seriously ill.

A 2007 Decima Research poll found that 79 per cent of Canadians surveyed reported going to work sick at some point in the previous year.