Elevated brain natriuretic peptide predicts mortality in interstitial lung disease

Elevated pulmonary vascular resistance portends a poor prognosis across interstitial lung disease (ILD), irrespective of the histospecific diagnosis. Currently, no noninvasive surrogate prognostic marker exists. We explore the prognostic value of brain natriuretic peptide (BNP) and echocardiography across ILD. ILD patients with BNP concentrations performed during 2005-2007 were reviewed (n = 90). Echocardiography tapes were reviewed by a cardiologist blinded to other results. Outcome was evaluated for survival against BNP and echocardiograph parameters. A priori threshold values and composite markers were evaluated against survival. During follow-up (20±9 months) there were 28 deaths (31%). BNP correlated with right heart echocardiographic indices, including right ventricular systolic pressure (RVSP) (R(2) = 0.18, p = 0.0002) but not with parameters of left heart function. Nonsurvivors had higher BNP and RVSP levels than survivors. BNP ≥20 pmol·L(-1) (hazard ratio (HR) 2.93, 95% CI 1.28-6.73; p = 0.01) and moderate-severe pulmonary hypertension (HR 2.53, 95% CI 1.15-5.57; p = 0.02) were associated with increased mortality, independent of age, sex and pulmonary function. Patients with BNP ≥20 pmol·L(-1) had a 14-fold increased mortality over those with BNP <4 pmol·L(-1). Increased BNP levels and/or echocardiographic markers of right ventricular dysfunction were associated with increased mortality across ILD. The link between vascular parameters and mortality supports the concept that pulmonary vascular disease contributes to the final common pathway seen across ILD.