Sickness absence is known to be an important cause of lost productivity. In the United States, for example, the total days lost due to sickness absence are estimated to represent 3–7% of all regularly scheduled work days.1 Sickness absence is also a measure of the use of health services and increasingly is considered a measure of health. Obviously, some sick leave represents voluntary absenteeism not related to physical or mental illness, and some employees work while ill and record no absences. However, this subjective component is an unlikely source of major bias in longer sick leaves requiring physician examination. Records of such absences have been found to be a more powerful predictor of all-cause mortality than established self-reported health measures and various objective measures of specific physical illnesses and medical conditions. They are also a strong predictor of specific causes of death, such as cardiovascular disease, cancer, alcohol-related causes and suicide, and future disability retirement.2 3 Furthermore, among employees reporting poor health, low medically certified sickness absences have been found to be associated with subsequent improvement in health status.4

Given that sickness absence represents a major public health burden on employees, employers, the health care system and …