Prevalence of the upper airway resistance syndrome in the general population

Abstract

Background : Upper airway resistance syndrome (UARS) shares common clinical features with obstructive sleep apnea and hypopnea (OSAH). It is characterized by repetitive respiratory effort-related arousal (RERA), which may lead to daytime sleepiness and functional impairment. Little is known about the prevalence of UARS in the general population. Objectives : To determine the prevalence of UARS in the general population and to compare its characteristics to matched control subjects without UARS. 2020 subjects (50.0% women, 57.3 ± 10.7 years old, BMI 25.5 ± 4.3 kg/m 2 ) participating in an ongoing population-based sleep cohort study (HypnoLaus, Lausanne, Switzerland) underwent complete polysomnographic recordings at home. Respiratory events were scored according to the AASM Chicago criteria. UARS was present if the RERA index was ⩾5/h and accounted for more than 50% of the respiratory disturbance index (RDI), which is defined by the sum of the apnea–hypopnea index (AHI) and RERA index. Characteristics of each subject with confirmed UARS were compared with 5 age and sex matched control subjects with similar AHI but no RERA. The prevalence of UARS was 0.84% of this general population sample. Median AHI and RDI were respectively 4.4/h (IQ range 3.5–6.8/h) and 10.7/h (IQ range 9.1–15.6/h). Mean Epworth Sleepiness Score was 6.6 ± 3.2; male-to-female ratio was 0.7. There were no significant differences between UARS subjects and the control subjects regarding BMI (24.7 ± 3.1 vs. 24.0 ± 3.3, p = 0.46) and the Epworth Sleepiness Score (6.6 ± 3.2 vs. 7.4 ± 2.5, p = 0.15). Also, the same prevalence of hypertension (29.4 ± 47.0% vs. 25.9 ± 19.7%, p = 0.77), diabetes (5.9 ± 24.2% vs. 5.9 ± 11.8%, p = 1.0) and metabolic syndrome (29.4 ± 47.0% vs. 12.9 ± 12.1%, p = 0.16) were found in UARS and control subjects. In our middle-aged population-based cohort, the prevalence of UARS is lower than previously reported. There was no significant difference between UARS and control subjects in terms of BMI, daytime sleepiness, hypertension, diabetes and metabolic syndrome. Funding: Ligue pulmonaire vaudoise, Fondation Leenaards, Fond national Suisse and GSK.