Predictors of obstructive sleep apnea

Abstract

Obstructive sleep apnea (OSA) is a disorder with a high prevalence not only in western societies. OSA is defined as an apnea-hypopnea index(AHI)> 5/hsleep, whereas OSA syndrome (OSAS) includes the symptoms associated with OSA. The current prevalence of OSA approximately amounts to 26 % (AHI ≥ 5) of the population in the US aged 30-70 years [13]. Worse sleep-disordered breathing (AHI ≥ 15) has a prevalence of 10 %. The prevalence varies depending on age, body mass index (BMI), and gender: Among 30-49-year-old men, the number of patients affected (AHI ≥ 15) is much higher (10 %) than among women of the same age (3 %). Reaching older ages (50-70 years), the numbers are higher, with prevalences of 17 % of men and 9 % of women with an AHI ≥ 15 [13]. These epidemiological estimations represent the increase of OSA over the last two decades, which is likely a result of the progressing obesity epidemic in the US [13].This gives an impression of how huge the number of people with OSAS really is. In many cases it is never diagnosed, due to a lack of symptoms such as daytime sleepiness or neurocognitive disorders. The situation is equivalent in European countries, where many cases of OSAS remain undetected. A recent populationbased study in Lausanne collected data of 2121 participants and found a prevalence of 83.8 % among men and 60.8 % among women with an AHI ≥ 5, whereas 49.7 % of the male and 23.4 % of the female participants actually had an AHI ≥ 15 [7].It has to be taken into consideration that only some affected persons have symptoms of OSAS that would help to detect it.The gold standard of OSAS diagnostics is polysomnography (PSG), but this is also very complex and expensive. Capacity is mostly limited and waiting periods extend to 6 months and longer. There is a discussion on the guidelines' recommendation to use polygraphy instead, in order to prescreen patients with suspected OSAS [14]. In the recent past, researchers took the initiative to simplify the diagnostic process, considering the fact that approximately 80 % of the people with OSA remain undiagnosed [5]. A recent pilot study analyzed the inability to fit hands around the neck as a predictor of OSA. This screening procedure has a positive predictive power of 100 %, but a negative predictive power of only 31.6 % for an AHI ≥ 5/h [5].Consequences of OSAS include worsening of cardiovascular disease with a negative impact on the general health condition of the patient, neurocognitive disorders, and a much higher risk for car accidents because of daytime sleepiness and inattentiveness [10,16]. Besides the effort to reduce the number of undiagnosed cases of OSA, it is of general interest among surgeons and anesthesiologists to estimate the postoperative outcome ofpatients with OSA [2]. Therefore, scientists developed a clinical screening in a sleep center, in a population with a high incidence of OSA. The test ought to define the severity of OSA and contains Mallampati Index, the distance between thyroid and chin (cm), neck circumference (cm), BMI (kg/m 2 ), and...