Initial risk assessment for pulmonary hypertension in patients with COPD

Abstract

Background Pulmonary hypertension (PH) is a comorbidity associated with increased mortality in chronic obstructive pulmonary disease (COPD) patients. It is not known which clinical markers are predictive of PH in COPD. The goal of this study was to develop a clinical tool to identify patients who should be sent for initial screening with echocardiography.

Methods Of 127 patients screened, 94 primary-care patients with COPD were enrolled. All underwent full pulmonary function testing, 6-minute walk distance (6MWD), exercise oximetry, Saint George’s Respiratory Questionnaire, and transthoracic echocardiography. Eighty-six patients had measurable pulmonary artery pressures (PAP) on echocardiography. Elevated PAP was defined as a systolic PAP > 35 mmHg.

Results Pre- and post-bronchodilator FEV1 (P = 0.04 and P = 0.03, respectively), exercise oxyhemoglobin desaturation (P = 0.003), and 6MWD (P = 0.004) were associated with elevated PAP on univariate analysis. Diffusion capacity was lower but did not reach statistical significance (P = 0.07). In multivariate analysis, statistically significant independent variables were >3% decrease in exercise oxyhemoglobin saturation and decline in prebronchodilator FEV1 (P = 0.01 and P = 0.04, respectively). A composite prediction model was developed that assigned one point for each of the following: age > 55 years, oxyhemoglobin desaturation > 3%, prebronchodilator FEV1 < 50% predicted, and 6MWD < 1175 ft. Prevalence rates of elevated PAP were 32% for a score of 0–1 (low risk), 68% for a score of 2 (moderate risk), and 78% for a score of 3–4 (high risk). The composite score exhibited a strong trend with elevated PAP prevalence (Cochrane-Armitage trend statistic P = 0.001).

Conclusion A simple prediction tool using routine office-based parameters can be used to identify COPD patients at high risk for elevated PAP and initiate the first step in screening for PH with echocardiography. It is important that right heart catheterization be performed to confirm the diagnosis and guide treatment decisions.