Kim L. Ward

Excessive daytime sleepiness increases the risk of motor vehicle crash in obstructive sleep apnea

STUDY OBJECTIVES (1) To describe the incidence rate of motor vehicle crashes (MVCs) in patients with obstructive sleep apnea (OSA); and (2) to investigate MVC risk factors in OSA patients. METHODS A retrospective case-series observational study was conducted using data from the West Australian Sleep Health Study at a tertiary hospital-based sleep clinic. Participants were patients (N = 2,673) referred for assessment of suspected sleep disordered breathing. Questionnaire data were collected including age, sex, years of driving, near-misses and MVCs, sleepiness, and consumption of alcohol and caffeinated drinks. Overnight laboratory-based polysomnography was performed using standard methodology.(1) Poisson univariate and negative binomial multivariable regression models were used to investigate associations between risk factors and MVC and near-miss risk in patients with untreated OSA. RESULTS In patients with untreated OSA, the crash rate was 0.06 MVC/person-year compared with the general community crash rate of 0.02 MVC/person-year. The rate ratio comparing very sleepy men with normal men was 4.68 (95% CI 3.07, 7.14) for near-misses and 1.27 (95% CI 1.00, 1.61) for crashes, after adjusting for confounders. In women there was a significant association with sleepiness score (p = 0.02) but no dose effect across quartiles. CONCLUSIONS Untreated OSA is associated with an increased risk of near-misses in men and women and an increased risk of MVCs in very sleepy men. There is a strong association between excessive daytime sleepiness and increased report of near-misses. Our data support the observation that it is those patients with increased sleepiness regardless of OSA severity who are most at risk.

Physical inactivity is associated with moderate-severe obstructive sleep apnea

STUDY OBJECTIVE To investigate whether low levels of physical activity were associated with an increased occurrence of obstructive sleep apnea (OSA), OSA-related symptoms, and cardiometabolic risk. METHODS A case-control study design was used. OSA cases were patients referred to a sleep clinic for suspected OSA (n = 2,340). Controls comprised participants from the Busselton community (n = 1,931). Exercise and occupational activity were derived from questionnaire data. Associations were modelled using logistic and linear regression and adjusted for confounders. RESULTS In comparison with moderate exercise, the high, low, and nil exercise groups had an odds ratio (OR) for moderate-severe OSA of 0.6 (95% CI 0.5-0.8), 1.6 (95% CI 1.2-2.0), and 2.7 (95% CI 1.9-3.7), respectively. Relative to men in heavy activity occupations, men in medium, light and sedentary occupations had an OR for moderate-severe OSA of 1.7 (95% CI 1.1-2.5), 2.1 (95% CI 1.4-3.2), and 1.8 (95% CI 1.2-2.8), respectively. Relative to women in medium activity occupations, women in light and sedentary occupations had an OR for moderate-severe OSA of 4.2 (95% CI 2.6-7.2) and 3.5 (2.0-6.0). OSA patients who adequately exercised had lower: levels of doctor-diagnosed depression (p = 0.047); symptoms of fatigue (p < 0.0001); systolic (p = 0.015) and diastolic blood pressure (p = 0.015); and C-reactive protein (CRP) (p = 0.003). CONCLUSIONS Low levels of physical activity were associated with moderate-severe OSA. Exercise in individuals with OSA is associated with lower levels of depression, fatigue, blood pressure and CRP.

Cohort profile: the Western Australian Sleep Health Study.

BackgroundEpidemiologic and genetic studies of obstructive sleep apnoea (OSA) are limited by a lack of large-scale, well-characterized OSA cohorts. These studies require large sample size to provide adequate power to detect differences between groups. This study describes the development of such a cohort (The Western Australian Sleep Health Study) in OSA patients of Caucasian–European origin attending the only public sleep clinic in Western Australia (WA).AimsThe main aim of the study is to phenotype 4,000 OSA patients in order to define the genetics of OSA and its co-morbidities. MethodsAlmost all underwent laboratory-based attended polysomnography (PSG).ResultsCurrently complete data (questionnaire, biochemistry, DNA, and PSG) has been obtained on over 3,000 individuals and will reach the target of 4,000 individuals by the end of 2010. In a separate but related study, we have developed a sleep study database containing data from all patients who have undergone PSG at the sleep laboratory since its inception in 1988 until the present day (over 30,000 PSG studies representing data from approximately 20,000 individuals). In addition, data from both cohorts have been linked prospectively to statutory health data collected by the WA Department of Health.ConclusionThis study will be the largest sleep clinic cohort database internationally with access to genetic and epidemiological data. It is unique among sleep clinic cohorts because of its size, the breadth of data collected and the ability to link prospectively to statutory health data. It will be a major tool to comprehensively assess genetic and epidemiologic factors determining OSA and its co-morbidities.