title: Receiver operating characteristics of impulse oscillometry parameters for predicting obstructive sleep apnea in preobese and obese snorers.
abstract: Inability to maintain upper-airway patency during sleep is a cause of obstructive sleep apnea (OSA) and its sequelae. The associated syndrome (OSAS) is common in obese populations, currently, nocturnal polysomnography is the gold standard for diagnosing this conditions, but the diagnostic procedures are expensive and time-consuming. Therefore, identification of new markers of OSAS would be useful. This study aims to examine the receiver operating characteristics of impulse oscillometry (IOS) parameters for the prediction of OSAS in preobese and obese snoring patients.
  
  
  
  In total, 230 patients with normal spirometric values were included in this cross-sectional study. Full laboratory polysomnography was performed and IOS measurements were determined in sitting and supine positions to obtain respiratory impedance (Zrs), resistance (Rrs), and reactance (Xrs) parameters. The respiratory resistance at zero-frequency (Rrs0) was extrapolated by linear regression analysis of Rrs versus low-oscillatory-frequencies and its inverse, respiratory conductance (Grs), was calculated.
  
  
  
  In both the sitting and supine positions Rrs0, Zrs, and Rrs at five oscillatory-frequencies (Hz) and Grs, the reciprocal of Zrs5 (Gz), and Xrs at 5 Hz all had significant positive or negative correlations with OSAS severity as defined by the Respiratory disturbance index (RDI). The correlation coefficients between Rrs0, Zrs5, Rrs5, Grs, Gz, Xrs5 measured in the supine and RDI were 0.425, 0.395, 0.378, -0.425, -0.395, and -0.517, respectively (all p < 0.001). The receiver operating characteristics curves showed that Xrs at 5 Hz (reactance) in the supine position was the best for predicting OSAS with a sensitivity of 73 % and specificity of 84 % at the optimal cut-off point of -0.23 (kPa s L(-1)). The other parameters also showed acceptable discriminating power. A logistic-regression model based on respiratory function abnormalities revealed that reactance combined with patient sex and lung volume yielded a specificity of 83.3 % with a sensitivity of 76.8 % for indicating OSAS.
  
  
  
  Respiratory resistance and reactance measured by IOS are abnormal in preobese and obese OSAS patients, and these parameters are moderate to closely correlated with OSAS severity. IOS might be a useful screening tool for detecting OSAS in clinic based populations.
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, The People's Hospital of Xinjiang Uygur Autonomous Region, Ürümqi, China.|Postgraduate College of Xinjiang Medical University, Ürümqi, China.
authors.forename: Arikin
authors.initials: A
authors.lastname: Abdeyrim
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, The People's Hospital of Xinjiang Uygur Autonomous Region, Ürümqi, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Tang
authors.affiliation: Department of Respiration Medicine, Xinjiang Petroleum Administration MingYuan Works Hospital, Ürümqi, China.
authors.forename: Arzugl
authors.initials: A
authors.lastname: Muhamat
authors.affiliation: Department of Hernia and Abdominal Wall Surgery & Minimally Invasive Surgery, The People's Hospital of Xinjiang Uygur Autonomous Region, Tianchi Road No. 91 Tianshan District, Ürümqi, Xinjiang, 830001, China. kelimuabudureyim@sina.com.
authors.forename: Kelimu
authors.initials: K
authors.lastname: Abudeyrim
authors.affiliation: Postgraduate College of Xinjiang Medical University, Ürümqi, China.
authors.forename: YongPing
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Hypertension Diagnosis and Treatment Center, The People's Hospital of Xinjiang Uygur Autonomous Region, Ürümqi, China.
authors.forename: NanFang
authors.initials: N
authors.lastname: Li
authors.affiliation: Laboratory of sleep study, The People's Hospital of Xinjiang Uygur Autonomous Region, Ürümqi, China.
authors.forename: Yinchun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Respiratory Function Test Department, The People's Hospital of Xinjiang Uygur Autonomous Region, Ürümqi, China.
authors.forename: Minghua
authors.initials: M
authors.lastname: Zhao
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D009991:Oscillometry; D050177:Overweight / Q000150:complications*; D017286:Polysomnography; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*; D013147:Spirometry; D013990:Tidal Volume
keywords: Obstructive sleep apnea syndrome (OSAS); Receiver operating characteristics (ROC); Respiratory function test