title: Obesity is associated with a lower resting oxygen saturation in the ambulatory elderly: results from the cardiovascular health study.
abstract: BACKGROUND
  The contribution of obesity to hypoxemia has not been reported in a community-based study. Our hypothesis was that increasing obesity would be independently associated with lower SpO2 in an ambulatory elderly population.
  
  
  METHODS
  The Cardiovascular Health Study ascertained resting SpO2 in 2,252 subjects over age 64. We used multiple linear regression to estimate the association of body mass index (BMI) with SpO2 and to adjust for potentially confounding factors. Covariates including age, sex, race, smoking, airway obstruction (based on spirometry), self reported diagnosis of emphysema, asthma, heart failure, and left ventricular function (by echocardiography) were evaluated.
  
  
  RESULTS
  Among 2,252 subjects the mean and median SpO2 were 97.6% and 98.0% respectively; 5% of subjects had SpO2 values below 95%. BMI was negatively correlated with SpO2 (Spearman R = -0.27, P < .001). The mean difference in SpO2 between the lowest and highest BMI categories (< 25 kg/m(2) and ≥ 35 kg/m(2)) was 1.33% (95% CI 0.89-1.78%). In multivariable linear regression analysis, SpO2 was significantly inversely associated with BMI (1.4% per 10 units of BMI, 95% CI 1.2-1.6, for whites/others, and 0.87% per 10 units of BMI, 95% CI 0.47-1.27, for African Americans).
  
  
  CONCLUSIONS
  We found a narrow distribution of SpO2 values in a community-based sample of ambulatory elderly. Obesity was a strong independent contributor to a low SpO2, with effects comparable to or greater than other factors clinically associated with lower SpO2.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, Washington 98104, USA.
authors.forename: Vishesh K
authors.initials: VK
authors.lastname: Kapur
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Wilsdon
authors.forename: David
authors.initials: D
authors.lastname: Au
authors.forename: Mark
authors.initials: M
authors.lastname: Avdalovic
authors.forename: Paul
authors.initials: P
authors.lastname: Enright
authors.forename: Vincent S
authors.initials: VS
authors.lastname: Fan
authors.forename: Nadia N
authors.initials: NN
authors.lastname: Hansel
authors.forename: Susan R
authors.initials: SR
authors.lastname: Heckbert
authors.forename: Rui
authors.initials: R
authors.lastname: Jiang
authors.forename: Jerry A
authors.initials: JA
authors.lastname: Krishnan
authors.forename: Kenneth
authors.initials: K
authors.lastname: Mukamal
authors.forename: Sachin
authors.initials: S
authors.lastname: Yende
authors.forename: R Graham
authors.initials: RG
authors.lastname: Barr
mesh_terms: D001741:Black or African American; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000208:ethnology / Q000503:physiopathology*; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D012907:Smoking / Q000503:physiopathology; D055105:Waist Circumference; D044465:White People
chemical_list: D010100:Oxygen