Association of Brain Natriuretic Peptide Levels at Time of Injury with Morbidity and Mortality in Patients with Surgically Treated Hip Fractures

Abstract

Background: An elevated brain natriuretic peptide (BNP) level has been shown to be associated with mortality and cardiac events in cardiac surgery, but its utility in the prediction of morbidity and mortality in hip fracture surgery is unknown. The primary aim of this study was to determine if there is a difference in BNP level at the time of injury between patients who do and do not develop complications after hip fracture surgery. The secondary aim was to determine if there is a predictive relationship between complications associated with the initial BNP level and mortality. Methods: A retrospective chart review of 455 hip fractures in patients ≥60 years old that were operatively treated between February 2014 and July 2018 was performed. Patients were included if they had a BNP level within 48 hours after injury (BNPi). Specific perioperative (≤7 days), 30-day, 1-year, and 2-year postoperative complications were recorded. Wilcoxon rank-sum tests were used to determine if higher BNPi values were associated with greater morbidity. The complications associated with higher BNPi values were further analyzed to assess if they were predictive of mortality, using univariate and multivariable analyses. Results: Higher BNPi was significantly associated with greater morbidity at all postoperative time points and with higher mortality at 1 and 2 years postoperatively. Furthermore, several complications including cardiac failure or exacerbation and altered mental status were associated with mortality at all time points in univariate analysis and at many time points in multivariable analysis. Conclusions: Patients with higher BNPi levels were more likely to develop complications up to 1 year postoperatively, and several of these complications were associated with increased mortality. Future studies to determine if delaying surgery until BNP levels are normalized or lowered may help guide management, and may be useful in determining the need for further medical optimization. Future studies aimed at defining a threshold BNP value at the time of injury may also help in better managing patients preoperatively. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.