NT-proBNP in chronic hypercapnic respiratory failure: a marker of disease severity, treatment effect and prognosis.

BACKGROUND

Natriuretic peptides are considered as reliable indicators of left-heart failure (HF) and are useful for differential diagnosis of dyspnoea.

AIM

We evaluated the clinical significance of N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with chronic hypercapnic respiratory failure (CHRF).

METHODS

In 60 patients with CHRF, plasma concentrations of NT-proBNP were assessed at baseline and after treatment including non-invasive ventilation (NIV). The relationship of NT-proBNP to disease severity and its predictive value for survival were evaluated up to 4 years.

RESULTS

NT-proBNP levels were markedly elevated in patients with CHRF (n=60; geometric mean (SD) 546.4 (4.9) pg/mL; p<0.001) compared to healthy controls (n=182; 49.0 (2.2) pg/mL). After excluding patients with concomitant HF or renal impairment, levels were still increased (n=43; 393.2 (3.8) pg/mL; p<0.001). According to multivariate regression, hypoxia and exacerbation independently determined NT-proBNP levels (p<0.05 each). After initiation of NIV, blood gases and lung function improved and NT-proBNP decreased (-31.3 (0.3)%; p<0.001). During 22.5 (2.2) months follow-up, NT-proBNP was not significantly associated with survival in the total population, however, the subgroup of patients with levels >722 pg/mL (67th percentile) and no adherence to NIV displayed poor prognosis (hazard ratio=0.21; 95%-CI=0.022-0.580; p=0.0091).

CONCLUSIONS

NT-proBNP was highly elevated in patients with CHRF and correlated with the degree of respiratory impairment and exacerbation. Correspondingly, treatment including NIV led to reduction of NT-proBNP. These data indicate a potential role of NT-proBNP in assessing disease severity, treatment efficacy and prognosis in CHRF.