J Korean Soc Emerg Med.  2021 Dec;32(6):575-585.

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

• Kim HS
• Jeong KY
• Choi HS
• Hong HP
• Lee JS
• Ko SH
• Kim SK

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.

Keyword

Pneumonia; Natriuretic peptides; Body mass index; Prognosis