Cohort profile: The Western Australian Sleep health study, a prospective sleep clinic cohort study

Abstract

Genetic and epidemiologic investigations into obstructive sleep apnoea (OSA) have been limited by a scarcity of sizeable well-characterised sleep clinic cohorts with laboratory-based polysomnography (PSG). This profile reports the characteristics of a prospective clinic cohort study exploring the genotypic and phenotypic features of OSA with ongoing patient follow-up to assess long-term health outcomes. The Western Australian Sleep Health Study (WASHS) recruited patients at a large tertiary hospital sleep clinic in Perth, Australia. Between 2006 and 2010, 5948 consecutive new adult patients attended the clinic and 4914 were eligible to participate following consent and screening. Among eligible patients, 98.5% (n = 4839) had diagnostic PSG available, and 86.0% (n = 4226) were comprehensively phenotyped by clinical questionnaire and anthropometric measurements. Among those comprehensively phenotyped, blood biospecimens for biochemistry and DNA were obtained in 2759 (65.2%), and linked health administrative data was requested in 2017 for 4067 patients (96.2%). The group of most interest, the comprehensively phenotyped patients (n = 4226), were predominantly male (60.6%), middle-aged (mean±SD: 50.5 ± 14.0 years), and obese (32.7 ± 7.7 kg/m²). The majority of this group were diagnosed with OSA (93.8%). The WASHS Prospective Sleep Clinic Cohort is amongst the largest OSA cohorts globally with PSG and long-term morbidity and mortality data. Comprehensive phenotype and genotype data have contributed to numerous publications on the epidemiology and genetics of OSA. Patients have been monitored by ongoing clinic review, where OSA treatment data is collected, and by follow-up studies, such as an Australian National Health and Medical Research Council funded project (2018–2021) investigating cardiovascular outcomes in OSA.