Predicting the outcome of hip fracture patients by using N-terminal fragment of pro-B-type natriuretic peptide

OBJECTIVE: To examine the prognostic value of perioperative N-terminal fragment of pro-brain natriuretic peptide (NT-proBNP) in hip fracture patients. DESIGN: Blinded prospective cohort study. SETTING: Single centre trial at Turku University Hospital in Finland. PARTICIPANTS: Inclusion criterion was admittance to the study hospital due to hip fracture during the trial period of October 2009—May 2010. Exclusion criteria were the patient's refusal and inadequate laboratory tests. The final study population consisted of 182 patients. PRIMARY AND SECONDARY OUTCOME MEASURES: NT-proBNP was assessed once during the perioperative period and later if clinically indicated, and troponin T (TnT) and ECG recordings were evaluated repeatedly. The short-term (30-day) and long-term (1000 days) mortalities were studied. RESULTS: Median (IQR) follow-up time was 3.1 (0.3) years. The median (IQR) NT-proBNP level was 1260 (2298) ng/L in preoperative and 1600 (3971) ng/L in postoperative samples (p=0.001). TnT was elevated in 66 (36%) patients, and was significantly more common in patients with higher NT-proBNP. Patients with high (>2370 ng/L) and intermediate (806–2370 ng/L) NT-proBNP level had significantly higher short-term mortality compared with patients having a low (<806 ng/L) NT-proBNP level (15 vs 11 vs 2%, p=0.04), and the long-term mortality remained higher in these patients (69% vs 49% vs 27%, p<0.001). Intermediate or high NT-proBNP level (HR 7.8, 95% CI 1.03 to 59.14, p<0.05) was the only independent predictor of short-term mortality, while intermediate or high NT-proBNP level (HR 2.27, 95% CI 1.30 to 3.96, p=0.004), the presence of dementia (HR 1.74, 95% CI 1.13 to 2.66, p=0.01) and higher preoperative American Society of Anesthesiologists’ (ASA) classification (HR 1.59, 95% CI 1.06 to 2.38, p=0.02) were independent predictors of long-term mortality. CONCLUSION: An elevated perioperative NT-proBNP level is common in hip fracture patients, and it is an independent predictor of short-term and long-term mortality superior to the commonly used clinical risk scores. TRIAL REGISTRATION NUMBER: NCT01015105; Results.