Obstructive sleep apnea in a random sample of Icelanders 40-65 years

Introduction We have previously reported prevalence rates in Iceland of 8% among middle age men and 2.5% among women with diagnosed obstructive sleep apnea based on a whole night study and clinical symptoms. The true prevalence in the general population has, however, not been estimated. Methods In an ongoing epidemiological study on asthma and allergy (www.ecrhs.org) a random population sample 40-65 years was invited for a type 3 home sleep study (T3, NoxMedical, Reykjavik, Iceland). Different screening tools including the Berlin Questionnaire (BQ) and the multiple apnea predictor (MAP) index were also administered. Results In January 2013, altogether 425 subjects had been invited and all but 23 had accepted participation (94.6%). Eleven studies are not technically usable and among the remaining 391, 17 subjects (4.3%) had been previously diagnosed with OSA. Altogether 218 had an apnea-hypopnea index (AHI) below 5(55.8%), 96 (24.5%) had AHI 5 - 15, 50 (12.7%) and AHI 15 - 30 and ten (2.8%) AHI above 30. On average, males had higher AHI than women. Moderate to severe OSA (AHI > 15) was found in 30% of subjects with body mass index (BMI) over 30 kg/m 2 (n=119) compared to 10% of those with BMI under 25 kg/m 2 (n=112). The screening properties of the BQ and MAP together with new questions on sleep related symptoms will be evaluated for sensitivity and specificity. Conclusion In a large sample of men and women from the general population some 20% have moderate to severe OSA. Undiagnosed OSA is a significant problem as only 1 in 4 general population subject has been diagnosed previously with OSA.