Effect of body mass index on the prognostic value of N-terminal pro-B-type natriuretic peptide in pneumonia: a comparative study between normal-weight and obese adults

ABSTRACT

Objective@#Body mass index (BMI) is a major determinant of N-terminal pro-brain natriuretic peptide (NT-proBNP). However, the relationship of BMI with pneumonia has not been entirely characterized. @*Methods@#Adult patients with pneumonia, who visited the emergency department from January 2017 to December 2019, were included. According to BMI, they were divided into two groups, including normal-weight and obesity groups. Data were retrospectively reviewed via the prospectively collected pneumonia registry and medical chart. NT-proBNP, BMI and pneumonia severity index (PSI) were determined for all subjects. The moderating effect between NT-proBNP and BMI was examined by entering interaction terms into the multivariable regression model predicting mortality. Using the area under the curve (AUC), the predictive performance of NT-proBNP was evaluated. @*Results@#Of 327 enrolled patients, 118 patients belonged to the obesity group. In a multivariable model including BMI, NT-proBNP was identified as an independent predictor of mortality. The AUC of the adjusted NT-proBNP including BMI, significantly increased the AUC of the adjusted NT-proBNP excluding BMI and tended to be superior to that of PSI. A positively significant BMI-by-NT-proBNP interaction for mortality was observed. NT-proBNP showed significant prognostic power in both BMI groups, but NT-proBNP of the obesity group had significantly higher AUC than that of the normalweight group. In the obesity group, the AUC of NT-proBNP tended to be higher than that of PSI. @*Conclusion@#BMI is a significant factor enhancing the prognostic power of NT-proBNP in pneumonia. The prognostic utility of NT-proBNP was significantly differed by BMI groups, which is more useful in the obesity group than the normalweight group.