Predictors of oxygen saturation ≤95% in a cross-sectional population based survey

Respir Med. 2012 Nov;106(11):1551-8. doi: 10.1016/j.rmed.2012.06.016. Epub 2012 Jul 13.


Background: Pulse oximetry has become an important tool in evaluating, and monitoring pulmonary diseases, but the knowledge about arterial oxygen saturation (SpO(2)) values in a general population is limited. The aim of this study was to describe the distribution of low pulse oximetry values in a general adult population and their association with certain predictors.

Methods: A cross-sectional population based survey was performed in Tromsø, Norway, in 2007-2008. Valid SpO(2) and pre-bronchodilator spirometry was recorded in 6317 participants aged 38-87 years (57% women). Resting SpO(2) ≤95% was defined as an abnormal value. Predictors of SpO(2) ≤95% with p < 0.05 were entered into a binary multivariable logistic regression.

Results: The prevalence of SpO(2) ≤95% was 6.3%. The strongest predictors in the logistic regression were increased body mass index (BMI) (OR of BMI ≥35 = 6.2, CI(4.2, 9.2)), and reduced forced expiratory volume in 1 s (FEV(1)) % predicted (OR of FEV1% predicted <50 = 4.1, CI(2.5, 6.7)), followed by increased age, male gender, and smoking (p < 0.001). Other significant predictors were elevated C-reactive protein (CRP) (p < 0.005), former smoking, breathlessness and elevated hemoglobin (p < 0.01).

Conclusion: Airflow limitation and other known signs of pulmonary diseases were, as expected, strongly associated with decreased oxygen saturation. Obesity was also a strong predictor of low SpO(2), and should be included among possible explanations when low SpO(2) values are encountered.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Body Mass Index
  • C-Reactive Protein / metabolism
  • Cross-Sectional Studies
  • Female
  • Forced Expiratory Volume / physiology
  • Hemoglobins / metabolism
  • Humans
  • Male
  • Middle Aged
  • Norway
  • Oximetry
  • Oxygen / blood*
  • Reference Values
  • Sex Characteristics
  • Smoking / blood
  • Vital Capacity / physiology


  • Hemoglobins
  • C-Reactive Protein
  • Oxygen