Polysomnographic analysis of respiratory events during sleep in young nonobese Japanese adults without clinical complaints of sleep apnea.

STUDY OBJECTIVES

The present study aimed to investigate the occurrence and characteristics of apnea-hypopnea events in young nonobese healthy Japanese participants.

METHODS

One hundred and three young adult participants without sleep complaints (men: 56; women: 47; age: 24.5 ± 3.0 years; body mass index: 20.9 ± 1.8 kg/m²) underwent 2-night polysomnography. Data on the 2nd night were scored according to American Academy of Sleep Medicine criteria version 2.1. The apnea-hypopnea index (AHI) was estimated. The arousal threshold was calculated in participants with AHI ≥ 5 events/h. Apnea-hypopnea events were rescored by 3 other criteria issued by the American Academy of Sleep Medicine (AASM): Chicago criteria in 1999 and recommended and alternative criteria in 2007.

RESULTS

Participants had good sleep characterized by high sleep efficiency (93.2%). Mean AHI of AASM 2.1 recommended criteria was 4.0 ± 5.3 events/h. AHI was significantly higher in men (median [range] = 4.0[.3-35.8] events/h) than in women (1.6 [.1-18.1] events/h). The prevalence rates of AHI ≥ 5 events/h and ≥ 15 events/h were 25.2 and 3.9%, respectively. The arousal threshold was estimated as -7.7 ± 2.6 cm H₂O. AHI was lower for AASM 2007 recommended criteria (.8 [.0-18.2 events/h]) and AASM 2007 alternative (2.0 [.1-32.2] events/h) than for AASM version 2.1 recommended criteria (2.4 [.1-32.9] events/h) and AASM Chicago (4.6 [.1-35.8] events/h). The percentage of participants with AHI ≥ 5 events/h was approximately 2-fold higher with AASM Chicago (44.6%) than with AASM version 2.1 recommended criteria.

CONCLUSIONS

The present study demonstrated that 25% of young nonobese Japanese participants had subclinical obstructive sleep apnea. The presence of frequent airflow limitations may be a risk factor for the development of obstructive sleep apnea in Japanese individuals.