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

BMC Pulmonary Medicine

Table 2 Logistic regressions of each predictive variable on polycythemia

Predictive variable	OR	95% CI	P value
FEV₁ percent predicted	0.98	0.97–1.00	0.014
DLCO percent predicted	0.98	0.96–0.99	< 0.0001
Percent emphysema on CT	1.02	1.00–1.04	0.051
Percent air trapping on CT	1.01	0.99–1.02	0.35
Pi10 on CT	0.99	0.70–1.41	0.96
PA/A ratio, > 1.0	0.80	0.42–1.52	0.50
Resting SpO₂
Normal (reference)	1.00
Mild hypoxemia	1.30	0.83–2.04	0.24
Moderate hypoxemia	1.90	1.02–3.53	0.044
Severe hypoxemia	3.32	1.50–7.33	0.0030
Exercise-induced desaturation	1.48	0.95–2.31	0.081
Obstructive sleep apnea
No (reference)	1.00
Without CPAP use	0.25	0.06–1.06	0.060
With CPAP use	0.80	0.34–1.87	0.61
Congestive heart failure	1.00	0.42–2.40	1.00
Chronic kidney disease	0.08	0.00–1.31	0.076
Diabetes mellitus	0.68	0.39–1.19	0.18

The reported OR and P values are from logistic regression models for the association of secondary polycythemia with each predictive variable adjusted for a core set of covariates and confounders including age, sex, race, body mass index, enrollment clinical center, smoking status, pack-years of cigarette smoking, and use of long-term oxygen therapy
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, Pi10 square root wall area of a theoretical airway of 10 mm internal perimeter, PA/A ratio ratio of the diameter of the pulmonary artery to the diameter of the aorta, SpO₂ oxyhemoglobin saturation measured by oximetry

ISSN: 1471-2466