Table 3.

Relationship between COPD severity and cognitive impairment

Disease severity measure	Risk of cognitive impairment
	Unadjusted OR (95% CI)	Multivariable OR (95% CI)†
Forced expiratory volume in 1 second*	0.97 (0.85–1.11) P = 0.63	0.93 (0.79–1.09) P = 0.35
Baseline oxygen saturation ≤88%‡	4.41 (0.92–21) P = 0.064	5.45 (1.014–29.2) P = 0.048
BODE Score*	1.13 (1.002–1.27) P = 0.046	1.08 (0.95–1.23) P = 0.25
COPD Severity Score*	1.08 (0.94–1.23) P = 0.28	1.03 (0.90–1.17) P = 0.66

^*odds ratio per ½ standard deviation decrement.

^†Separate multivariable logistic regression analysis for each severity measure plus age, sex, race, educational attainment, and smoking history.

^‡61 subjects had oxygen saturation measured on supplemental oxygen (range 1–4 liters/minute). When oxygen use was added to the multivariable model, low oxygen saturation remained associated with a greater risk of cognitive impairment (OR 5.46; 95% CI 1.007–30; P = 0.049). In additional analysis, oxygen flow rate (no oxygen, flow = 0 liters/minute) was added to the multivariable model with minimal impact on the results (OR 5.44; 95% CI 1.008–29; P = 0.049).

Abbreviations: BODE, BMI (Body Mass Index), Obstruction, Dyspnea, Exercise Capacity; CI, confidence interval; COPD, chronic obstructive pulmonary disease; OR, odds ratio.