Sleep-Disordered Breathing in the Usual Lifestyle Setting as Detected with Home Monitoring in a Population of Working Men in Japan

SLEEP-RELATED HEALTH PROBLEMS AND THEIR IMPACT ON SOCIETY AND ON INDIVIDUALS ARE A MAJOR SOCIAL ISSUE. PEOPLE WITH SLEEP-DISORDERED breathing (SDB) are at increased risk for hypertension,1,2 cardiovascular diseases,3 and mortality.3,4 However, SDB and obstructive sleep apnea syndrome (OSAS) are prevalent but largely undiagnosed in adults.5 In spite of this wide population of undiagnosed patients, in-laboratory sleep-recording capacity has remained limited. This current situation presents an urgent need to move toward the use of portable monitors in home settings. Epidemiologic studies for SDB and OSAS have been conducted not only in Western countries,1–5 but also in Asian countries.6,7 However, sound estimates of SDB prevalence in Japan are lacking: previous Japanese studies have been limited by use of nonprobability samples, low response rates, small samples, and other methodologic problems. All previous Japanese epidemiologic studies on SDB and OSAS were performed with type 4 portable monitors.8–10 In our current study, a cardiorespiratory monitoring device (also referred to as a type 3 portable monitoring device) was used together with actigraphy at home to analyze SDB. Type 3 portable monitors are defined as devices with a minimum of 4 channels monitored,11 including ventilation or airflow (at least 2 channels of respiratory movement or respiratory movement and airflow), heart rate or electrocardiogram, and oxygen saturation, whereas portable monitors that do not meet these criteria are designated as type 4.11 Attended type 3 sleep studies are thought to be a standard method and an alternative for polysomnography in the diagnosis and follow-up for SDB and OSAS.12 On the other hand, type 4 portable monitors are not recommended for diagnosis because they have a higher percentage of false-positive results and high rates of false negatives or conflicting results.11 Most epidemiologic studies have been performed with polysomnography in laboratory settings. Using in-laboratory polysomnography as the gold standard has limitations in validity, partly because subjects tend to sleep more poorly in the laboratory than at home.11 In this study, participants were asked to follow their usual lifestyles, and sleep recordings were performed at home. Home monitoring that more closely reflects the subjects' usual drinking and sleeping habits may present a different prevalence or different outcomes than those from previous reports in the laboratory settings. Recently, obesity has become a major social problem in Japan. The prevalence of obesity (body mass index: [BMI] ≥ 25) in 1983, 1993, and 2003 was 26.7%, 24.5% and 34.4%, respectively, among the Japanese male general population aged 40 to 49 years.13 Obesity and weight gain are positively associated with SDB.14 Thus, SDB may become more prevalent than has been previously reported in Japanese. The primary goal of this paper was to examine the prevalence of home-monitored SDB and OSAS in a Japanese working population. The secondary goal was to test the hypotheses that home monitoring with a type 3 portable monitor and actigraphy can produce reliable data to analyze SDB in usual lifestyles. Here, we report the first epidemiologic study in Japan with a type 3 portable monitor and actigraphy at home to examine the prevalence and related factors of SDB.