Unveiling the Silent Killer: Sleep Disordered Breathing and Mortality

Dr Robert Gibbins, a prominent figure in the field of sleep disorders, emphasizes the gravity of the situation: “This is a statistic that should get the attention of anyone with sleep apnoea. The majority who do, do not even know they have it, because it does not cause pain or overt symptoms. If you or your partner is a snorer and who demonstrates a degree of excessive tiredness or drowsiness, you should consult a practitioner who works on this field a lot and have a diagnostic sleep test. It may save a life.”

Sleep Disordered Breathing (SDB), a condition characterised by frequent breathing pauses during sleep, has long been recognised as a significant health concern. However, its association with mortality in the general population has not been extensively studied. A landmark study conducted by Terry Young, PhD, and colleagues from the University of Wisconsin-Madison sheds light on this issue through an eighteen-year follow-up of the Wisconsin Sleep Cohort.

The study, published in Sleep in 2008, utilised polysomnography, the clinical gold standard for diagnosing SDB, to assess a population-based sample of 1522 individuals. Severity of SDB was categorized based on the number of apnoea and hypopnea episodes per hour of sleep, with cutpoints at 5, 15, and 30 distinguishing mild, moderate, and severe SDB, respectively.

The findings revealed a striking association between untreated SDB and mortality risk. Even after adjusting for age, sex, body mass index (BMI), and other potential confounders, individuals with severe SDB were found to have a threefold increase in the risk of all-cause mortality compared to those without SDB. Furthermore, the risk remained substantially elevated even after excluding individuals who had received continuous positive airway pressure (CPAP) treatment, highlighting the gravity of untreated SDB. For cardiovascular mortality specifically, the risk was even more pronounced, with a more than fivefold increase in individuals with severe SDB.

Importantly, these results underscore the critical importance of clinical recognition and treatment of SDB, irrespective of the presence of symptoms such as daytime sleepiness. The study emphasizes that frequent episodes of apnoea and hypopnea, rather than just symptomatic presentation, should prompt intervention to mitigate the substantial mortality risk associated with this condition.

In conclusion, the study by Young et al. provides compelling evidence of the significant mortality risk posed by untreated SDB, independent of age, sex, and BMI. By shedding light on this often under-diagnosed condition, the findings advocate for increased awareness, early detection, and appropriate management of SDB to mitigate its adverse health outcomes.

Reference

Young, T., Finn, L., Peppard, P. E., Szklo-Coxe, M., Austin, D., Nieto, F. J., Stubbs, R., & Hla, K. M. (2008). Sleep disordered breathing and mortality: eighteen-year follow-up of the Wisconsin sleep cohort. SLEEP, 3. Retrieved from https://sleepcohort.wisc.edu/wp-content/uploads/sites/1452/2020/10/2008augmortalityincohort.pdf