People who drag themselves in to work despite feeling ill are doubling the likelihood of developing heart disease, a 10-year study of 10,000 Britons has revealed.
Even suffering from an illness as minor as a common cold can put unnecessary strain on a worker's heart that can accelerate coronary heart
disease, according to the findings of the Whitehall study into occupational health.
The disclosure will provoke a debate among employers' organisations over whether staff should be encouraged to take time off work when they feel unwell.
Professor Sir Michael Marmot, the head of the study at University College London, said that "presenteeism" leads to an increase in coronary heart disease.
"Among 30 to 40 per cent of the population, we have found that those who were unwell but took no absence at all from work had double the incidence of coronary heart disease over the following years," he said.
Sir Michael, one of the world's leading epidemiologists, added: "So many people force themselves in to work when they are not well and have little knowledge of the consequences. Far from contributing to their companies or spreading a few germs around the office, they could be hastening their own deaths."
The Whitehall study, a Government-funded survey of Britain's occupational health, examined the fitness and attendance of 10,308 civil servants across Greater London over 10 years.
Scientists from University College compared attendance rates with the health records of civil servants.
The results showed that 40 per cent of those who did not take time off when they had fallen ill - even with ailments as minor as a cold - had double the incidence of coronary disease over the next few years.
Sir Michael said that this effect held true regardless of how much someone smoked or drank.
"The data seems to show that the stress prompted by going to work when ill is an independent factor when calculating the risk to an employee's health through coronary heart disease," he said.
Occupational health specialists say the findings raised challenging questions for doctors and employers.
