Progression of obstructive sleep apnoea syndrome in Japanese patients

The aggravation of obstructive sleep apnoea syndrome (OSAS) is reportedly associated with weight gain. The present study investigated the factors associated with worsening of respiratory functional parameters in Japanese OSAS patients who showed no body weight change during the follow-up period. A follow-up polysomnography (PSG) was performed in 82 patients with a mean of 7.5 years after the diagnostic PSG, and the apnoea-hypopnoea index (AHI), respiratory event duration, minimum percutaneous oxygen saturation (SpO(2)), baseline SpO(2), and 3 % oxygen desaturation index (ODI) during sleep were compared between the two PSGs. Furthermore, factors associated with worsened AHI, respiratory event duration, and minimum SpO(2) were investigated using logistic regression analysis. No significant differences were observed in AHI, baseline SpO(2,) and 3 % ODI between the two PSGs. However, there was a significantly increased respiratory event duration and decreased minimum SpO(2) observed. In addition, 17 patients had a a parts per thousand yen25 % AHI increase, and the age of 40-60 years and initial OSAS severity (mild and moderate) were the significantly associated factors. Age of a parts per thousand yen60 years and a baseline body mass index (BMI) of a parts per thousand yen25 kg/m(2) were significantly associated with prolonged respiratory event duration. The age of 40-60 years was significantly associated with decreased minimum SpO(2). Untreated middle-aged patients may be at a high risk for worsened AHI and SpO(2) even without weight gain.