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Obesity hypoventilation syndrome in J apan and independent determinants of arterial carbon dioxide levels
Author(s) -
Harada Yuka,
Chihara Yuichi,
Azuma Masanori,
Murase Kimihiko,
Toyama Yoshiro,
Yoshimura Chikara,
Oga Toru,
Nakamura Hiroshi,
Mishima Michiaki,
Chin Kazuo
Publication year - 2014
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1111/resp.12367
Subject(s) - medicine , obesity hypoventilation syndrome , carbon dioxide , obesity , hypoventilation , cardiology , food science , respiratory system , ecology , chemistry , biology
Background and objective Obesity hypoventilation syndrome ( OHS ) prevalence was previously estimated at 9% in patients with obstructive sleep apnoea ( OSA ) in J apan. However, the definition of OSA in that study was based on an apnoea‐hypopnoea index ( AHI ) of ≥ 20/h rather than ≥ 5/h. Therefore, the prevalence of OHS in OSA was not measured in the same way as for Western countries. Our study objectives were to investigate the characteristics of Japanese patients with OHS . Methods Nine hundred eighty‐one consecutive patients investigated for suspected OSA were enrolled. At least 90% of them were from urban areas, including 162 with obese OSA (body mass index ( BMI ) ≥ 30 kg/m 2 and AHI ≥ 5/h). Results The prevalence of OHS ( BMI 36.7 ± 4.9 kg/m 2 ) in OSA and that in obese OSA were 2.3% and 12.3%, respectively. Multiple regression analysis revealed that independent of age and BMI, arterial oxygen pressure (contribution rate (R 2 ) = 7.7%), 4% oxygen desaturation index (R 2 = 8.9%), carbon monoxide diffusing capacity/alveolar volume (R 2 = 8.3%), haemoglobin concentration (R 2 = 4.9%) and waist circumference (R 2 = 4.9%) were independently associated with arterial carbon dioxide pressure. After 12.3 ± 4.6 months of CPAP treatment, more than 60% of OHS patients no longer had hypercapnia. Conclusions The prevalence of OHS in OSA in J apan was 2.3%. The mean BMI of patients with OHS in J apan was lower than that in Western countries (36.7 kg/m 2 vs 44.0 kg/m 2 ).