title: Ambulatory oximetry fails to predict survival in chronic obstructive pulmonary disease with mild-to-moderate hypoxaemia.
abstract: OBJECTIVE
  Although long-term oxygen therapy is one of few treatments known to improve survival in COPD, no patient subgroup likely to derive benefit has been identified in over 30 years. We assessed the prognostic value of point measurement of P(a) O(2) and proportion of ambulatory oximetry with saturations below 90% in this context.
  
  
  METHODS
  Subjects were community-living patients with COPD and P(a) O(2) 56-70 mm Hg when stable. Baseline assessments included clinical, physiological and laboratory assessments, as well as 24-h ambulatory oximetry. Patients were followed to death from any cause, first exacerbation and first admission.
  
  
  RESULTS
  Despite poor survival overall, there was no significant difference in prognosis between mildly hypoxaemic and moderately hypoxaemic patients. There were also no significant differences for secondary end-points (exacerbation and hospital admission). On multivariate analysis, trends were observed towards improved survival, with higher P(a) O(2) and greater proportion of ambulatory oximetry below 90%.
  
  
  CONCLUSIONS
  Neither resting P(a) O(2) nor proportion of ambulatory oximetry below 90% saturation effectively predicted survival in COPD.
authors.affiliation: Department of Respiratory and Sleep Disorders Medicine, Western Hospital, Footscray, Victoria, Australia. james@msdc.com.au
authors.forename: James M
authors.initials: JM
authors.lastname: Trauer
authors.forename: Chelsea A
authors.initials: CA
authors.lastname: Gielen
authors.forename: Ali
authors.initials: A
authors.lastname: Aminazad
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Steinfort
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001784:Blood Gas Analysis; D015897:Comorbidity; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000453:epidemiology / Q000628:therapy*; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood* / Q000627:therapeutic use*; D011237:Predictive Value of Tests; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology / Q000401:mortality* / Q000628:therapy*; D012044:Regression Analysis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015996:Survival Rate; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D010100:Oxygen