Heart Damage Biomarker Can Help Diagnose PH-COPD, Study Suggests

Marta Figueiredo, PhD avatar

by Marta Figueiredo, PhD |

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High blood levels of NT-proBNP — a validated and widely accepted prognostic marker of pulmonary hypertension (PH) — may serve as a biomarker to diagnose PH among people with chronic obstructive pulmonary disease (COPD) exacerbations, according to a study in China.

However, no significant association was detected between NT-proBNP levels and PH severity in COPD patients with exacerbations (AECOPD), or periods of symptom worsening.

The study, “NT-pro BNP in AECOPD-PH: old biomarker, new insights-based on a large retrospective case-controlled study,” was published in the journal Respiratory Research.

COPD is characterized by chronic inflammation in the airways sacs, where gas exchanges occur, that damages lung tissue and impairs breathing. Pulmonary hypertension, or high blood pressure in the blood vessels that supply the lungs, is a major complication of COPD that increases the risk of right heart failure.

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COPD patients may experience chest tightness, shortness of breath, and cough due to either disease exacerbations or PH. Given the PH-associated heart failure risk, biomarkers are needed to identify those with PH (PH-COPD).

High blood levels of NT-proBNP, a marker of heart damage, have been shown to predict disease progression in people with PH. However, whether NT-pro BNP levels could be used to distinguish COPD patients with PH from those without PH remains unclear.

To address this, a team of researchers in China retrospectively analyzed NT-pro BNP levels of 178 people with stable COPD, 206 AECOPD patients with PH, and 688 AECOPD patients without PH.

All patients were followed at the First Affiliated Hospital of Xinjiang Medical University and their demographic, clinical, and lab data were also collected. None had chronic heart insufficiency.

The median age of the patients was 73 years, and nearly 26% of them were women. About 35% previously or currently smoked. Most (75.7%) AECOPD-PH patients had mild or moderate pulmonary hypertension.

Results showed that the AECOPD-PH group had significantly higher blood levels of NT-proBNP than AECOPD patients without PH (median of 273.53 vs. 93.4 picograms per milliliter, or pg/mL).

After adjusting for potential influencing factors, the researchers found that NT-proBNP levels between 271–1165 pg/mL and those higher than 1165 pg/mL were associated with an increased risk of having PH.

Further analysis showed that 175.14 pg/mL of NT-proBNP was the best threshold to separate AECOPD-PH patients from those without PH, correctly identifying nearly 62% of AECOPD-PH cases and correctly ruling out approximately 64% of AECOPD patients without PH.

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Total bilirubin, a liver function marker, was also found to have diagnostic value for AECOPD-PH, but its ability to discriminate between AECOPD-PH and AECOPD patients was inferior to that of NT-proBNP.

As such, NT-proBNP “was the most suitable biomarker for diagnosing AECOPD-PH,” the researchers wrote.

Its levels, however, were only weakly associated with PH severity in AECOPD patients, as well as with the levels of other biomarkers, such as total bilirubin.

These findings suggest that “for AECOPD patients, NT-proBNP measurement may help identify patients with PH,” the researchers wrote.

They noted, however, that larger, follow-up studies are needed to confirm the diagnostic value of NT-proBNP levels in AECOPD patients with PH.