People with sleep apnoea have an increased risk of needing to take long-term sick leave or give up working completely. So concludes a major Norwegian study on over 7,000 subjects, to be published in the European Respiratory Journal (ERJ), the scientific publication of the European Respiratory Society (ERS). This finding is especially alarming since sleep apnoea, although widespread, is little known not only to the public but also to many doctors.

Snoring and sleep apnoea, constant fatigue and daytime sleepiness may all point to obstructive sleep apnoea syndrome, which is caused by repeated episodes of upper airway obstruction at night. Such interruptions to breathing lead to fragmented sleep and a reduction in blood oxygen levels. At least 5% of the population suffers from the condition. In fact, specialists believe that the real figure is likely to be much higher, and emphasise that obstructive sleep apnoea syndrome is little known to the public and to many doctors. Diagnosis, which can be made tentatively following discussion with the patient, may be confirmed by the doctor by means of a polysomnographic recording made overnight. However, this specialized test is not applied systematically.

Sleep apnoea is more widespread among overweight patients and those with high blood pressure, diabetes or cardiovascular disease. As many studies have found, the condition is far from harmless. If left untreated, it can have serious consequences: an increased risk of death (be it from road accidents or heart disease), a considerable reduction in quality of life, and a predisposition to diabetes, impotence and strokes.

Yet little research had taken place to evaluate sleep apnoea's impact on professional life. So Børge Sivertsen (Department of Clinical Psychology, University of Bergen, Norway) and his Norwegian and Australian colleagues decided to take a closer look.

Over 7,000 subjects aged 40-45

The participants in their study, whose results are published today in the ERJ, were recruited from within the Hordaland Health Study (Husk), a vast epidemiological study. In total, the cohort consists of 29,400 subjects living in the county of Hordaland in western Norway, aged 40 to 45 when they joined the study between 1997 and 1999. Out of 8,896 randomly selected subjects, Sivertsen and his team retained 7,028 as participants in their study. They had all completed a questionnaire to identify symptoms of obstructive sleep apnoea, such as snoring or interruptions to breathing (noted by the subjects themselves or their partners).

In parallel, the researchers recorded the frequency of episodes of fatigue and sleepiness at work or during free time. Finally, Sivertsen obtained data from the Norwegian national medical insurance fund concerning long-term sick leave (over eight weeks) and permanent health-related inability to work registered for the subjects.

Impact on work almost doubled

The results are striking: 6.3% of subjects were considered to be affected by obstructive sleep apnoea syndrome (with a disproportionately high number of men and people with a low educational level), and the authors conclude that these patients have almost double the risk (1.7 times, to be precise) of needing to take long-term sick leave. The increase in risk is independent of the other parameters, the team emphasises in the ERJ.

Furthermore, patients with sleep apnoea were also found to have double the risk of needing to retire from work on health grounds. The researchers believe this link may be partially explained by the depressive syndromes that often accompany sleep apnoea. "Even when all of the other variables are accounted for, obstructive sleep apnoea syndrome remains a significant risk factor for ill-health retirement (the relative risk is 1.92)", Sivertsen points out.

Closer examination reveals that, of the three symptoms recorded by the questionnaires, daytime sleepiness seems to contribute the most to the need for sick leave and ill-health retirement. "Better identification of sufferers and earlier treatment should significantly reduce these socio-economic consequences," according to Sivertsen.

"Where a patient complains of poor sleep, doctors should thus look for other symptoms of sleep apnoea, such as snoring, pauses in breathing and daytime sleepiness, and if necessary send the patient to a specialised service for polysomnographic testing," he concludes.

The effect of OSAS on sick leave and work disability

About the European Respiratory Journal (ERJ)

The European Respiratory Journal is the peer-reviewed scientific publication of the European Respiratory Society (more than 8,000 specialists in lung diseases and respiratory medicine in Europe, the United States and Australia).

European Respiratory Journal