title: Low FEV1, smoking history, and obesity are factors associated with oxygen saturation decrease in an adult population cohort.
abstract: BACKGROUND
  Worsening of pulmonary diseases is associated with a decrease in oxygen saturation (SpO2). Such a decrease in SpO2 and associated factors has not been previously evaluated in a general adult population.
  
  
  OBJECTIVE
  We sought to describe SpO2 in a sample of adults, at baseline and after 6.3 years, to determine whether factors predicting low SpO2 in a cross-sectional study were also associated with a decrease in SpO2 in this cohort.
  
  
  METHODS
  As part of the Tromsø Study, 2,822 participants were examined with pulse oximetry in Tromsø 5 (2001/2002) and Tromsø 6 (2007/2008). Low SpO2 by pulse oximetry was defined as an SpO2 ≤ 95%, and SpO2 decrease was defined as a ≥ 2% decrease from baseline to below 96%.
  
  
  RESULTS
  A total of 139 (4.9%) subjects had a decrease in SpO2. Forced expiratory volume in 1 second (FEV1) <50% of the predicted value and current smoking with a history of ≥ 10 pack-years were the baseline characteristics most strongly associated with an SpO2 decrease in multivariable logistic regression (odds ratio 3.55 [95% confidence interval (CI) 1.60-7.89] and 2.48 [95% CI 1.48-4.15], respectively). Male sex, age, former smoking with a history of ≥ 10 pack-years, body mass index ≥ 30 kg/m(2), and C-reactive protein ≥ 5 mg/L were also significantly associated with an SpO2 decrease. A significant decrease in FEV1 and a new diagnosis of asthma or chronic obstructive pulmonary disease during the observation period most strongly predicted a fall in SpO2. A lower SpO2 decrease was observed in those who quit smoking and those who lost weight, but these tendencies were not statistically significant.
  
  
  CONCLUSIONS
  A decrease in SpO2 was most strongly associated with severe airflow limitation and a history of smoking. Smoking cessation and reducing obesity seem to be important measures to target for avoiding SpO2 decreases in the general population.
authors.affiliation: Department of Respiratory Medicine, University Hospital of North Norway, Tromsø, Norway ; Department of Community Medicine, University of Tromsø, Tromsø, Norway.
authors.forename: Monica Linea
authors.initials: ML
authors.lastname: Vold
authors.affiliation: Department of Respiratory Medicine, University Hospital of North Norway, Tromsø, Norway ; Department of Clinical Medicine, University of Tromsø, Tromsø, Norway.
authors.forename: Ulf
authors.initials: U
authors.lastname: Aasebø
authors.affiliation: Department of Community Medicine, University of Tromsø, Tromsø, Norway.
authors.forename: Hasse
authors.initials: H
authors.lastname: Melbye
mesh_terms: D000368:Aged; D001249:Asthma / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000517:prevention & control; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D015999:Multivariate Analysis; D009664:Norway / Q000453:epidemiology; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D016017:Odds Ratio; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000517:prevention & control; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology*; D016540:Smoking Cessation; D000074606:Smoking Prevention; D013147:Spirometry; D011795:Surveys and Questionnaires; D013997:Time Factors; D015431:Weight Loss
chemical_list: D015415:Biomarkers; D010100:Oxygen
keywords: cohort study; general population; lung function; pulse oximetry