Demographic characteristics of 3,659 Japanese patients with obstructive sleep apnea-hypopnea syndrome diagnosed by full polysomnography: associations with apnea-hypopnea index.

Information on obstructive sleep apnea-hypopnea syndrome (OSAHS) in Japan has been limited. The purposes of this clinical study were to evaluate the demographic characteristics of Japanese OSAHS patients and to assess how demographic factors are associated with OSAHS severity. We analyzed 3,659 OSAHS patients who underwent polysomnographic evaluation between January 2000 and December 2004 at 11 hospitals in Niigata Prefecture, Japan. Data consisted of apnea-hypopnea index (AHI) and demographic characteristics, including sex, age, and body-mass index, for statistical analysis. Levels of obesity were classified according to the WHO criteria. The male-to-female patient ratio for OSAHS was 4.6, and male patients presented more severe OSAHS than female patients. High AHI and a high proportion of moderate to serious OSAHS (AHI > or = 15) were found among the patients in their 30s, as well as female patients in their 70s and male patients in their 80s. The AHI and the proportion of moderate-to-serious OSAHS (AHI > or = 15) were greater in patients classified as underweight than in normal weight patients. In conclusion, there is a higher male predominance in the prevalence of OSAHS, and in both sexes, the results suggest different pathophysiological mechanisms of deteriorating OSAHS between adults under age 55 and adults 55 years or over. In addition, underweight patients exhibit more severe OSAHS than normal weight patients.

Serotonin-2A and 2C receptor gene polymorphisms in Japanese patients with obstructive sleep apnea.

OBJECTIVE: The serotonin (5-HT) 2A and 2C receptor subtype plays an important role in the maintenance of upper airway stability and normal breathing in obesity. Polymorphisms in the 5-HT 2A receptor gene (HTR2A) and 5-HT 2C receptor gene (HTR2C) are associated with various diseases. The aim of this study was to investigate whether or not the HTR2A/C genotypes are associated with obstructive sleep apnea (OSA). METHODS: The PCR-restriction fragment length polymorphism method was used to determine genotypes of the HTR2A/C gene. The genotype distributions and allele frequencies were statistically analyzed. SUBJECTS: We studied 177 consecutive male patients with excessive daytime somnolence and an apnea plus hypopnea number [apnea-hypopnea index (AHI)] of greater than five per hour of sleep established by full polysomnography. One hundred Japanese men in whom OSA was clinically excluded were randomly selected as a control group. RESULTS: Genotypes and allele frequencies of 102T/C polymorphism of the HTR2A and 796G/C polymorphism of the HTR2C did not differ between controls and patients with OSA. HTR2C polymorphism was considered inappropriate for association studies because of low frequency of the mutant allele. Multiple regression analysis showed that age and body mass index (BMI) were significantly associated with OSA, but HTR2A polymorphisms were not. HTR2A polymorphisms had no significant relationship with AHI or BMI, although further study with more samples will be needed for powerful statistical analyses. CONCLUSIONS: These results indicate that age and BMI, not these polymorphisms, are associated with OSA in this population.

Facial axis angle as a risk factor for obstructive sleep apnea.

OBJECTIVE: Many Japanese patients with obstructive sleep apnea (OSA) are less obese than Caucasian OSA patients despite their similar severity of OSA, suggesting that their etiology of OSA may differ. The purpose of this study was to identify bony factors associated with OSA in the Japanese population. METHODS: The clinical records of study subjects were retrospectively reviewed, and cephalometric measurements based on Sella-Nasion references and the Ricketts method were statistically compared. PATIENTS: Two hundred and six consecutive Japanese men complaining of habitual snoring and daytime sleepiness were enrolled in the study. All subsequently underwent an overnight polysomnographic examination. RESULTS: Multiple regression analysis showed that the body mass index (p<0.0001) and facial axis angle (p=0.007) were the dominant overall determinants for the apnea hypopnea index. The sella to nasion to subspinale angle (SNA) and sella to nasion to supramentale angle (SNB) were lower in the non-obese, severe group than for non-obese, mild and moderate patients with OSA (p=0.0047 and 0.0016, respectively). CONCLUSION: The risk factors for OSA in Japanese men may be obesity and the dolico facial pattern seen by the Ricketts method. In addition, a smaller SNA and SNB seem to be associated with the severity of OSA in non-obese patients.