Polysomnographic characteristics and predictors of positional obstructive sleep apnea in Japanese elderly.

Sleep problems and obstructive sleep apnea (OSA) increase with age and disturb life in old age. Positional therapy is one option to treat OSA, but the differences in clinical pathophysiology between elderly and other age groups have not been fully investigated. We explored the pathophysiological features of sleep apnea, factors that are independently associated with positional OSA and the prevalence in elderly patients. We studied demographic and polysomnographic data of 85 elderly individuals with OSA (age ≥ 65 years) and 124 non-elderly patients with OSA (age, 20-64 years). The Amsterdam Positional OSA Classification (APOC) was used to evaluate positional OSA. Body mass index (BMI) and Epworth sleepiness scale were both significantly lower in the elderly group than in the non-elderly group, although apnea/hypopnea index (AHI) did not differ between groups. OSA severity affected total sleep time, sleep efficiency, and waking after sleep onset more in the elderly than in the non-elderly. AHI in the lateral position was significantly lower in elderly than in non-elderly, although AHI in the supine position was almost the same between two groups. The distribution of APOC 1 and 2 (lateral sleep effective) was significantly higher in the elderly than in the non-elderly. Relative factors such as BMI, rate of hypopnea, and lowest SpO