title: Measurement of dyspnea in patients with obstructive sleep apnea.
abstract: OBJECTIVE
  Patients with obstructive sleep apnea (OSA) frequently complain of exertional dyspnea. We aimed to assess its related factors and the significance of its measurement in OSA.
  
  
  METHODS
  We evaluated 301 subjects with suspected OSA for dyspnea during activities of daily living using the Medical Research Council (MRC) scale. We analyzed the relationships between MRC grades and various subjective and objective indices. Further, the relationship of disease severity based on the apnea/hypopnea index (AHI) with these indices was examined. Results were compared between those obtained using MRC grades and the AHI.
  
  
  RESULTS
  Of 301 subjects, 265 were diagnosed with OSA. Their MRC scores were worse than in non-OSA patients. Among OSA patients, 125 had MRC grade 1 (mild), 121 had MRC grade 2 (moderate), and 19 had MRC grade 3 or more (severe) dyspnea. Various measurements differed significantly between groups categorized according to the MRC scale although determinants between mild and moderate groups and between moderate and severe groups differed. AHI categorizations were not significantly related to patient-reported measurements such as the Medical Outcomes Study 36-item short form, Pittsburgh Sleep Quality Index, and Hospital Anxiety and Depression Scale scores, unlike categorization based on the MRC scale.
  
  
  CONCLUSIONS
  Dyspnea is an important outcome in OSA although dyspnea in OSA patients is unrelated to the sleep disorder per se. Measurement of dyspnea in patients with OSA might provide further insights into the health of these patients and clinical manifestations of this disease.
authors.affiliation: Department of Respiratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Aihara
authors.forename: Toru
authors.initials: T
authors.lastname: Oga
authors.forename: Chikara
authors.initials: C
authors.lastname: Yoshimura
authors.forename: Takefumi
authors.initials: T
authors.lastname: Hitomi
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Chihara
authors.forename: Yuka
authors.initials: Y
authors.lastname: Harada
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Murase
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Toyama
authors.forename: Kiminobu
authors.initials: K
authors.lastname: Tanizawa
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Handa
authors.forename: Tomomasa
authors.initials: T
authors.lastname: Tsuboi
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mishima
authors.forename: Kazuo
authors.initials: K
authors.lastname: Chin
mesh_terms: D000203:Activities of Daily Living / Q000145:classification; D000328:Adult; D000368:Aged; D004417:Dyspnea / Q000145:classification / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012129:Respiratory Function Tests; D020181:Sleep Apnea, Obstructive / Q000145:classification / Q000175:diagnosis*; D013223:Statistics as Topic