Characteristics of Chronic Obstructive Pulmonary Disease Patients with Pulmonary Hypertension Assessed by Echocardiography in a Three-Year Observational Cohort Study

Figures & data

Figure 1 Process of patient selection in this study. Only data from COPD patients with spirometrically confirmed COPD (FEV₁/FVC < 0.7), as well as CT and echocardiography measurements at baseline, were selected and analyzed.

Abbreviations: COPD, chronic obstructive pulmonary disease; SPAP, systolic pulmonary artery pressure; CT, computed tomography; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity.

Table 1 Baseline Characteristics of the Study Population

	COPD Patients with Estimated eSPAP	COPD Patients Without Estimated eSPAP	p-value
	N = 183	N=115
Age, years	74 (67–79)	72(67–77)	0.07
Sex, female, n (%)	23 (12.6)	8(7.0)	0.36
Smoking index, pack-years	46.5 (35.3–70.1)	51(38–76.1)	0.64
Current smokers, n (%)	17 (9.3)	17(15.0)	0.09
FEV1/FVC, %	55.2 (42.3–64.2)	53.6(44.4–62.6)	0.94
%FEV1, %	66.7 ± 21.7	58.2 ± 21.0	0.03
COPD grade^a 1/2/3/4, n (%)	56/84/34/9 (30.6/45.9/18.6/4.9)	17/55/31/12 (14.8/47.8/27.0/10.4)	0.09

Notes: Data are presented as the mean ± SD, median (IQR), or number (%). ^aDefined by the Global Initiative for Chronic Obstructive Lung Disease.

Abbreviations: PH, pulmonary arterial hypertension; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; %FEV₁, forced expiratory volume in 1 second as a percentage of the predicted forced expiratory volume in 1 second; GOLD, Global Initiative for Chronic Obstructive Lung Disease; SD, standard deviation; IQR, interquartile range.

Figure 2 Distribution of eSPAP in the study population with PH assessed by echocardiography. Shaded bars indicate patients with PH.

Abbreviations: eSPAP, estimated systolic pulmonary artery pressure; PH, pulmonary arterial hypertension.

Table 2 Comparison of the Characteristics Stratified by the Presence of PH

	COPD Patients Without PH	COPD Patients with PH	p-value
N	143	40
Pulmonary artery pressure, mmHg^a	27.0 (23.0–30.0)	38.8 (36.0–53.0)	<0.01
Age, years^a	73.0 (67.0–79.0)	75.5 (71.3–80.0)	0.04
Sex, female, n (%)^c	17 (11.9)	6 (15.0)	0.60
Smoking index, pack-years^a	46.0 (35.2–70.1)	51.0 (37.9–68.9)	0.84
Current smokers, n (%)^c	15 (10.7)	2 (5.1)	0.29
Cancer, n (%)^c	24 (21.4)	11 (30.6)	0.26
Coronary artery disease, n (%)^c	15 (13.4)	2 (5.6)	0.20
LTOT, n (%)^c	9 (11.0)	2 (7.4)	0.59
Prescription of diuretics, n (%)^c	0(0%)	8(5.6%)	0.04
Prescription of vasodilators, n (%)^c	0(0%)	1(0.7%)	0.48
SpO2, %^a	96.0 (95.0–97.0)	96.0 (95.0–97.0)	0.75
BMI, kg/m^2b	22.8 ± 3.0	21.6 ± 3.0	0.02
CRP, mg/dl^a	0.06 (0.03–0.20)	0.07 (0.03–0.30)	0.28
WBC,/µL^a	6000 (5100–7400)	6000 (5025–8000)	0.60
BNP, pg/mL^a	24.2 (11.9–47.2)	33.1 (18.5–92.8)	0.01
LVEF, %^a	76.0 (72.0–80.0)	74.0 (71.0–81.8)	0.60
IVC, cm^a	1.3 (1.1–1.5)	1.3 (1.0–1.4)	0.97
LVEDD, cm^b	4.4 ± 0.5	4.4 ± 0.7	0.96
LVESD, cm^a	2.7 (2.4–3.0)	2.7 (2.4–3.2)	0.64

Notes: Data are presented as the mean ± SD, median (IQR), or number (%). Data were compared between two groups using ^aMann–Whitney U-test, ^bStudent’s t-test, and ^cχ² test.

Abbreviations: PH, pulmonary arterial hypertension; COPD, chronic obstructive pulmonary disease; LTOT, long-term oxygen therapy; SpO₂, oxygen saturation of peripheral artery; BMI, body mass index; CRP, C-reactive protein; WBC, white blood cell count; BNP, brain natriuretic peptide; LVEF, left ventricular ejection fraction; IVC, inferior vena cava; LVEDD, left ventricular end-diastolic diameter; LVESD, left ventricular end-systolic diameter; SD, standard deviation; IQR, interquartile range.

Figure 3 Association of PH assessed by echocardiography and health status in COPD patients. (A) Comparison of baseline CAT scores between the two groups. (B–E) Comparison of baseline SGRQ scores between the two groups. Data were compared between groups using the Mann–Whitney U-test.

Abbreviations: PH, pulmonary arterial hypertension; COPD, chronic obstructive pulmonary disease; CAT, COPD assessment test; SGRQ, St. George’s respiratory questionnaire.

Table 3 Comparison of Lung Function Parameters Between COPD Patients with and Without PH

	COPD Patients Without PH	COPD Patients with PH	p-value
N	143	40
FEV1^a	1830 (1320–2250)	1410 (912.5–1995.0)	<0.01
%FEV1^b	68.1 ± 20.8	61.4 ± 24.2	0.09
%DLCO^b	77.9 ± 25.1	61.6 ± 24.9	<0.01
%TLC^b	101.2 ± 14.7	98.8 ± 13.5	0.40
%IC^b	117.3 ± 24.7	110.9 ± 24.4	0.20
IC/TLC^b	0.43 ± 0.08	0.39 ± 0.07	0.02
%RV^a	95.1 (82.4–112.8)	101.1 (77.3–115.8)	0.93
RV/TLC^a	0.39 (0.32–0.45)	0.34 (0.31–0.40)	0.06

Notes: Data are presented as the mean ± SD or median (IQR). Data were compared between groups using ^athe Mann–Whitney U-test, or ^bthe Student’s t-test.

Abbreviations: COPD, chronic obstructive pulmonary disease; PH, pulmonary arterial hypertension; FEV₁, forced expiratory volume in 1 second; %FEV₁, forced expiratory volume in 1 second as a percentage of predicted forced expiratory volume in 1 second; DL_CO, diffusing capacity of the lung for carbon monoxide; TLC, total lung capacity; IC, inspiratory capacity; RV, residual volume; SD, standard deviation; IQR, interquartile range.

Figure 4 Relationship between PH assessed by echocardiography and lung diffusion capacity. (A) Correlation between eSPAP and %DL_CO in COPD patients. (B) ROC curves of %DL_CO for the prediction of PH assessed by echocardiography. Correlations between continuous variables were evaluated using Spearman’s rank correlation coefficient.

Abbreviations: PH, pulmonary arterial hypertension; eSPAP, estimated systolic pulmonary artery pressure; DL_CO, diffusing capacity of lung carbon monoxide; COPD, chronic obstructive pulmonary disease; ROC, receiver operating characteristic.

Table 4 Predictors for the Presence of PH According to Multivariate Logistic Regression Analysis

Parameters	Odds Ratio (95% CI)	p-value
LAA% ≥ 30%	7.1 (2.5–20.2)	<0.01
Interstitial lung abnormalities	3.8 (1.5–9.6)	<0.01

Abbreviations: PH, pulmonary arterial hypertension; LAA%, ratio of the low-attenuation area to the total lung volume, CI, confidence interval.

Figure 5 Relationship between PH assessed by echocardiography and baseline chest CT abnormalities in COPD patients. (A) Comparison of LAA% between the two groups. (B) Frequencies of emphysema severities in the two groups. (C) Comparison of WA% between the two groups. (D) Frequencies of interstitial abnormalities in the two groups. Data were compared between groups using the Mann–Whitney U-test and χ² test.

Abbreviations: PH, pulmonary arterial hypertension; CT, computed tomography; COPD, chronic obstructive pulmonary disease; LAA%, ratio of the low-attenuation area to the total lung volume; WA%, percentage of airway wall area.

Figure 6 Relationship between PH assessed by echocardiography and ratio of pulmonary artery diameter to aortic artery diameter. (A) Correlation between eSPAP and PA/Ao in COPD patients. (B) ROC curves of PA/Ao for the prediction of PH assessed by echocardiography. Correlations between continuous variables were evaluated using Spearman’s rank correlation coefficient.

Abbreviations: PH, pulmonary arterial hypertension; eSPAP, estimated systolic pulmonary artery pressure; PA/Ao, ratio of pulmonary artery diameter to aortic artery diameter; COPD, chronic obstructive pulmonary disease; ROC, receiver operating characteristic.

Figure 7 Frequency of COPD exacerbations over three years according to the presence or absence of PH assessed by echocardiography. Data were compared between groups using χ² test.

Abbreviations: COPD, chronic obstructive pulmonary disease; PH, pulmonary arterial hypertension.