You may think Lausanne is just a pretty town on the side of the Lake of the same name or home of the more notorious International Olympic Committee, a more powerful cartel than OPEC these days.
Or if you are a real afficianado of Swiss chocolate and food, you will know Lausanne houses the food technology centre of Nestle. You won’t find George Clooney operating their original Nespresso machine but it is an amazing research building (below) a bit like Dr Evil’s lair in Austin Powers – the Spy who Shagged Me.
This week new research from Dr. Raphael Heinzer (below) and colleagues from the Faculty of Biology and Medicine of Lausanne, Lausanne University Hospital suggests sleep apnea may be extremely common in their home town. Their population-based study (HypnoLaus) in Lausanne obtained home sleep study data from 2121 people of 3043 invited to participate. The prevalence of moderate-to-severe sleep-disordered breathing (≥15 events per h) was 23·4% (95% CI 20·9–26·0) in women and 49·7% (46·6–52·8) in men.
Before you start thinking that Raphael only selected chocolate over-indulgers or “IOC heavies”, the mean body-mass index (BMI) was a fairly svelte (by middle aged standards) of 25·6 kg/m². The upper quartile for the apnoea-hypopnoea index (>20·6 events per h) was associated independently with the presence of hypertension (odds ratio 1·60, 95% CI 1·14–2·26; p=0·0292 for trend across severity quartiles), diabetes (2·00, 1·05–3·99;p=0·0467), metabolic syndrome (2·80, 1·86–4·29; p<0·0001), and depression (1·92, 1·01–3·64; p=0·0292). The high prevalence may be due to use of more accurate nasal flow measurements in their home study technology. Also some bias cannot be excluded because there was not universal particpation but the study population seemed consistent with Lausanne demographics
These are important data but before you start investing your money in CPAP makers or dental device constructors, the authors do point out that many patients were not sleepy and it was hard to find too many people in this middle aged population who were “normal breathers”. In fact the median oxygen desaturation index >3% (dips in oxygen level) was 14·4 in men and 6·9 in women. An apnoea/hypopnoea index of five or more events per h (ie, considered by some as diagnostic at least mild sleep apnea) was recorded in 83·8% of men and 60·8% of women !! Importantly no association was noted between severity of sleep-disordered breathing and presence of daytime sleepiness, measured with the Epworth sleepiness scale. Either this scale should be thrown out and replaced by objective measures or the “sleepy sleep apnea” phenotype has little to do with frequency of apneas and hypopneas.
What is a safe level of sleep apnea ? Like cholesterol and blood pressure, intervention research with CPAP or other treatments are needed on a large scale to decide when you need to treat sleep apnea. As the paper saysys “These results, and the progressive association between severity of sleep-disordered breathing and cardiovascular, metabolic, and psychiatric diseases, suggest that an arbitrary threshold for the apnoeahypopnoea index could be hard to define and clinical decisions might need a complete clinical picture to be well informed.”
The scary thing is the prevalence of more severe forms of sleep apnea may be much higher in countries with higher levels of obesity than Lausanne. Its time Nestle put their efforts into producing great chocolate without the calories.
Professor Ron Grunstein is a Sleep Disorder Specialist based in Sydney, who consults at the Woolcock Clinic and Royal Prince Alfred Hospital and undertakes research at the Woolcock Institute, University of Sydney.