Follow-up study of patients with chronic obstructive pulmonary disease complicated with pulmonary hypertension

Abstract

Objective: To investigate the relationship between clinical characteristics of patients with chronic obstructive pulmonary disease (COPD) with pulmonary hypertension (PH) and COPD exacerbation over a three-year observation period. Methods: A total of 366 cases of stable COPD patients were enrolled from the Department of Respiratory Medicine of the First Affiliated Hospital of Henan University of Science and Technology. The patients underwent pulmonary function tests(PFT), COPD assessment test (CAT), Saint George's respiratory questionnaire (SGRQ), transthoracic echocardiogrophy(TTE), chest CT and biochemical detection. The likelihood of PH was evaluated based on the peak tricuspid regurgitation velocity (TRV) measured by echocardiography at rest and other indicators, which were represented by low, medium, and high probability, respectively. Highly probability was defined as PH. The mean values of the groups were compared using a two-tailed unpaired t test for normally distributed variables. Qualitative data were assessed using a χ2 test. Pearson correlation analysis was performed, and risk factors were analyzed using logistic regression analysis and stepwise regression analysis. P<0.05 was considered to indicate statistical significance. Results: The prevalence of patients with high likelihood of PH was 18.3% (n=67) in a series of 366 patients with COPD. The median estimated systolic pulmonary artery pressure in patients with PH was (51.7±6.7) mmHg(1mmHg=0.133 kPa). There were differences between patients with high likelihood of PH and those with low to moderate likelihood of PH for the following factors: age (76.0 vs. 64.0), body mass index (BMI) [(21.4±6.0) kg/m2 vs. (22.6±7.2)kg/m2], brain natriureticpeptide (BNP) [(50.8±9.1) pg/ml vs. (36.4±8.1) pg/ml], toral number of acute exacerbation in three-year [(6.1±0.1) times vs. (2.8±0.4) times], CAT (17.0 vs. 10.0), SGRQ (48.9 vs. 32.1), carbon monoxide diffusion percentage of predicted value (DLCO%) [(51.9±21.9)% vs. (67.0±22.1)%]; all the differences being statistically significant(mean P<0.05).There was a negative correlation between DLCO% and SPAP (r=-0.28, P<0.01).In patients with high likelihood of PH, the percentage of low attenuation area (LAA%) and interstitial abnormalities in chest CT were higher than those in patients with low to moderate likelihood of PH (56.1% vs. 34.3% and 30.8% vs. 15.6%, mean P<0.05).LAA% ≥ 30% and pulmonary interstitial abnormalities were independent risk factors for pH [beta value were 1.479, 1.065, OR value was (3.640-5.720), 95%CI (1.462-8.571), mean P<0.01]. The ratio of main pulmonary diameter to aortic artery diameter was significantly correlated with estimated systolic pulmonary artery pressure(r=-0.35, P<0.01).Age ≥75 years, FEV1%predicted value<50% and the presence of PH increased the likelihood of exacerbations of COPD over three years[beta value (0.459-1.211), OR value (3.643-5.722), 95%CI (1.463-8.904), mean P<0.01]. Conclusions: COPD patients with high likelihood of PH assessed by echocardiography were older, had a lower BMI, and presented with a worse health status compared to those with low to moderate likelihood of PH. The presence of PH assessed by echocardiography was related to future COPD exacerbations in COPD patients, and emphysema was closely related to PH assessed by echocardiography.