Secondary polycythemia in chronic obstructive pulmonary disease: prevalence and risk factors

BMC Pulmonary Medicine

Table 3 Multivariable logistic regression for polycythemia in COPD

Predictive variable	OR	95% CI	P value
Sex, male	3.60	2.20–5.90	< 0.0001
Race, non-Hispanic white	3.33	1.71–6.50	0.0004
Age at visit (year)	0.99	0.95–1.02	0.35
Center, Denver	4.42	2.38–8.21	< 0.0001
Body mass index (kg/m²)	1.03	0.99–1.07	0.19
Smoking status, current	2.55	1.49–4.38	0.0007
Pack-years of smoking	0.99	0.98–1.00	0.20
FEV₁% predicted	1.00	0.98–1.01	0.59
DLCO % predicted	0.98	0.96–0.99	0.0022
Percent emphysema on CT	0.99	0.96–1.01	0.31
Resting SpO₂
Normal (reference)	1.00
Mild desaturation	1.02	0.60–1.72	0.95
Moderate desaturation	1.43	0.68–2.99	0.35
Severe desaturation	3.50	1.41–8.66	0.0068
Exercise-induced desaturation	1.64	0.96–2.77	0.068
LTOT use
No use (reference)	1.00
Intermittent	0.49	0.12–2.04	0.32
Nocturnal	0.46	0.21–0.97	0.041
Continuous	0.13	0.05–0.35	< 0.0001
Obstructive sleep apnea
No diagnosis (reference)	1.00
Without CPAP treatment	0.39	0.11–1.41	0.15
With CPAP treatment	0.91	0.36–2.27	0.84
Chronic kidney disease	0.13	0.01–2.14	0.16

The reported OR and P values are from a single multivariable regression model
Bold numbers indicate values with statistical significance P < 0.05
OR odds ratio, CI confidence interval, FEV1 forced expiratory volume in 1 s, DLCO diffusing capacity of lung for carbon monoxide, SpO2 oxyhemoglobin saturation measured by oximetry, LTOT long-term oxygen therapy, CPAP continuous positive airway pressure

ISSN: 1471-2466