Worsening of pulmonary diseases is associated with a decrease in oxygen saturation (SpO 2). Such a decrease in SpO 2 and associated factors has not been previously evaluated in a general adult population.
We sought to describe SpO 2 in a sample of adults, at baseline and after 6.3 years, to determine whether factors predicting low SpO 2 in a cross-sectional study were also associated with a decrease in SpO 2 in this cohort.
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 SpO 2 by pulse oximetry was defined as an SpO 2 ≤95%, and SpO 2 decrease was defined as a ≥2% decrease from baseline to below 96%.
A total of 139 (4.9%) subjects had a decrease in SpO 2. Forced expiratory volume in 1 second (FEV 1) <50% of the predicted value and current smoking with a history of ≥10 pack-years were the baseline characteristics most strongly associated with an SpO 2 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 SpO 2 decrease. A significant decrease in FEV 1 and a new diagnosis of asthma or chronic obstructive pulmonary disease during the observation period most strongly predicted a fall in SpO 2. A lower SpO 2 decrease was observed in those who quit smoking and those who lost weight, but these tendencies were not statistically significant.