Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study.

Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study.

 Heinzer et. A. Lancet Respir Med 2015; 3:310-318

 

What it is?

Sleep disordered breathing is a chronic disorder caused by repeated upper-airway collapse during sleep, resulting in recurrent nocturnal asphyxia, fragmented sleep, major fluctuations in blood pressure, and increased sympathetic nervous system activity1. (The sympathetic nervous system is responsible for the release of norepinephrine and adrenaline causing the effects seen during the fight-or-flight response, including pupil dilation, increased sweating, increased heart rate, and increased blood pressure).

 

Why does it matter?

Previous studies have linked patients with untreated sleep-disordered breathing to an increased risk of hypertension, stroke, heart failure, diabetes, car accidents and depression.

Research done in the late 1980’s and 1990’s estimated that between 6.5-9% of women and 17-31% of men have untreated sleep-disordered breathing.  More recent studies have estimated the prevalence to be around 35% in men aged 30-70 years and 17% in women aged 30-70 years.

 

How was it studied?

Between 2003-2006 a large study (6733 randomly selected patients aged 35-75yrs) was conducted in Lausanne, Switzerland examining the prevalence of cardiovascular risk factors and psychiatric disorders in the general population and to identify genetic determinants and mechanisms involved in their association.  A 5-yr follow-up study from 2009-2012 was conducted and these same patients underwent a second physical exam and psychiatric testing (including the evaluation of sleep-related complaints coupled with documentation using the Berlin questionnaire, the Epworth sleepiness scale and the Pittsburgh sleep quality index).  At this follow-up study patients were invited to undergo polysomnography overnight at their homes to evaluate their quality of sleep.  2168 individuals accepted the invitation and 2121 polysomnographic recordings were included in the analysis.  What is unique about this study in particular is that it measured the prevalence of sleep-disordered breathing directly in the general population rather than estimating it.  It also used currently recommended techniques (including nasal pressure sensors) and scoring criteria to evaluate sleep disordered breathing.

 

What were the results?

This study recorded a much higher than previously estimated prevalence of sleep-disordered breathing and an independent association between the disorder and diabetes, hypertension, metabolic syndrome, and depression.  The data from this study suggested that diabetes seems to have a bidirectional association with Sleep Disordered Breathing.  Intermittent hypoxemia (reduced blood oxygen levels) contributes to development of insulin resistance and glucose intolerance, AND type 2 diabetes increases an individual’s predisposition to sleep-disordered breathing.  Even sleep disordered breathing of the lowest severity (>5events/hr) was associated with hypertension and depression.  Further, using the most recent definitions for respiratory events and diagnositic techniques commonly used in all modern sleep laboratories, it was found that every individual examined had some degree of sleep-disordered breathing.

 

What does this mean?

What the results of this study suggest is that Sleep Disordered Breathing is a clinically important disease, rather than a condition that is being over-diagnosed in otherwise healthy individuals.  The progressive association between sleep disordered breathing and cardiovascular disease, metabolic illness and psychiatric diseases suggests that routine screening for patients with complaints of snoring and other sleep-related complaints is critical in assessing and addressing risk factors for the progression of systemic illness and improving our populations health and quality of life.