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

BMC Pulm Med. 2021 Jul 14;21(1):235. doi: 10.1186/s12890-021-01585-5.

Abstract

Background: Secondary polycythemia is associated with cigarette smoking and chronic obstructive pulmonary disease (COPD). However, the prevalence of polycythemia in COPD and the contributing risk factors for polycythemia in COPD have not been extensively studied.

Methods: We analyzed the presence of secondary polycythemia in current and former smokers with moderate to very severe COPD at the five-year follow-up visit in the observational COPDGene study. We used logistic regression to evaluate the association of polycythemia with age, sex, race, altitude, current smoking status, spirometry, diffusing capacity for carbon monoxide (DLCO), quantitative chest CT measurements (including emphysema, airway wall thickness, and pulmonary artery to aorta diameter ratio), resting hypoxemia, exercise-induced hypoxemia, and long-term oxygen therapy.

Results: In a total of 1928 COPDGene participants with moderate to very severe COPD, secondary polycythemia was found in 97 (9.2%) male and 31 (3.5%) female participants. In a multivariable logistic model, severe resting hypoxemia (OR 3.50, 95% CI 1.41-8.66), impaired DLCO (OR 1.28 for each 10-percent decrease in DLCO % predicted, CI 1.09-1.49), male sex (OR 3.60, CI 2.20-5.90), non-Hispanic white race (OR 3.33, CI 1.71-6.50), current smoking (OR 2.55, CI 1.49-4.38), and enrollment in the Denver clinical center (OR 4.42, CI 2.38-8.21) were associated with higher risk for polycythemia. In addition, continuous (OR 0.13, CI 0.05-0.35) and nocturnal (OR 0.46, CI 0.21-0.97) supplemental oxygen were associated with lower risk for polycythemia. Results were similar after excluding participants with anemia and participants enrolled at the Denver clinical center.

Conclusions: In a large cohort of individuals with moderate to very severe COPD, male sex, current smoking, enrollment at the Denver clinical center, impaired DLCO, and severe hypoxemia were associated with increased risk for secondary polycythemia. Continuous or nocturnal supplemental oxygen use were associated with decreased risk for polycythemia.

Keywords: COPD; DLCO; Hypoxemia; Oxygen therapy; Polycythemia.

Publication types

  • Multicenter Study
  • Observational Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Carbon Monoxide / blood
  • Cigarette Smoking / adverse effects*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Hypoxia / complications
  • Logistic Models
  • Male
  • Middle Aged
  • Oxygen Inhalation Therapy / methods
  • Polycythemia / epidemiology*
  • Polycythemia / etiology*
  • Prevalence
  • Prospective Studies
  • Pulmonary Disease, Chronic Obstructive / complications*
  • Pulmonary Disease, Chronic Obstructive / therapy
  • Pulmonary Emphysema / diagnostic imaging
  • Risk Factors
  • Severity of Illness Index
  • Sex Factors
  • Spirometry
  • Tomography, X-Ray Computed
  • United States / epidemiology

Substances

  • Carbon Monoxide