Extremely High NT-proBNP in Unselected Hospital Admissions: A Retrospective Analysis of Diagnoses and Outcomes

BACKGROUND: Elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations are commonly interpreted as suggestive of heart failure (HF) but may also occur in the context of acute systemic illness and infection. OBJECTIVES: To evaluate diagnoses and outcomes among hospitalised adults with extremely high NT-proBNP. DESIGN: Retrospective cohort study. PARTICIPANTS: Adult hospital admissions with NT-proBNP concentrations ≥ 20,000 pg/mL. MAIN MEASURES: Clinical and laboratory data as well as primary diagnosis and all-cause mortality were recorded. Survivors and non-survivors at 6 months were compared. Overall survival was assessed using Kaplan-Meier analysis; associations with mortality were evaluated using multivariable Cox regression. KEY RESULTS: A total of 415 admissions were included. Median age was 82 years (IQR 73-88), 51.6% were male and median NT-proBNP was 35,000 pg/mL (IQR 26,563-35,000). The most common imaging findings were pulmonary congestion (55.4%) and infection (53.7%). Infection was the most common primary diagnosis (60%) and cause of death (71%), while HF was the primary diagnosis in 19%. Mortality was high: 43.6% in hospital and 64.5% at 6 months. Patients with infection had significantly higher mortality than those with other diagnoses. Cox regression showed older age and lower serum albumin were independent predictors of mortality. CONCLUSION: In unselected hospitalised patients, extremely high NT-proBNP levels were more frequently associated with infection and high mortality than with HF. NT-proBNP values occurred across a heterogenous range of acute illnesses and should be interpreted within the wider clinical context rather than as evidence of a single disease process.