PURPOSE: This study aimed to investigate the probability of 30-day mortality based on body mass index (BMI) assessment combined with pneumonia severity index (PSI) in patients with community-acquired pneumonia (CAP) and to determine whether being underweight is an independent risk factor contributing to 30-day mortality. BASIC PROCEDURES: A prospectively collected database was analyzed retrospectively. Multivariable logistic regression analysis was performed to determine whether BMI is an independent predictor of mortality in patients with CAP by adjusting for PSI and other factors found significant in univariable analysis. Mortality predictability of BMI and PSI was evaluated using area under the receiver operating characteristic curve analyses. MAIN FINDINGS: A total of 1403 patients were assessed in this study. In multivariable regression analysis, severe thinness (BMI<16 kg/m2), hypoalbuminemia (albumin<3.3 mg/dL), and PSI IV and V were predictive factors for 30-day mortality in patients with CAP. In terms of mortality prediction, the accuracy of PSI was 0.67 (95% confidence interval [CI], 0.63-0.71) as measured by the area under the receiver operating characteristic curve. When hypoalbuminemia was combined with PSI, the predictive accuracy significantly increased to 0.71 (95% CI, 0.66-0.75; P=.02). The addition of severe thinness to PSI and hypoalbuminemia further increased the accuracy significantly to 0.74 (95% CI, 0.70-0.78) (P=.005). PRINCIPAL CONCLUSIONS: Severe thinness (BMI<16 kg/m2) was associated with 30-day mortality in patients with CAP, showing improved prognostic performance when combined with PSI. We propose that physicians consider a patient's nutritional state using BMI when predicting mortality in CAP.
PURPOSE: This study aimed to investigate the probability of 30-day mortality based on body mass index (BMI) assessment combined with pneumonia severity index (PSI) in patients with community-acquired pneumonia (CAP) and to determine whether being underweight is an independent risk factor contributing to 30-day mortality. BASIC PROCEDURES: A prospectively collected database was analyzed retrospectively. Multivariable logistic regression analysis was performed to determine whether BMI is an independent predictor of mortality in patients with CAP by adjusting for PSI and other factors found significant in univariable analysis. Mortality predictability of BMI and PSI was evaluated using area under the receiver operating characteristic curve analyses. MAIN FINDINGS: A total of 1403 patients were assessed in this study. In multivariable regression analysis, severe thinness (BMI<16 kg/m2), hypoalbuminemia (albumin<3.3 mg/dL), and PSI IV and V were predictive factors for 30-day mortality in patients with CAP. In terms of mortality prediction, the accuracy of PSI was 0.67 (95% confidence interval [CI], 0.63-0.71) as measured by the area under the receiver operating characteristic curve. When hypoalbuminemia was combined with PSI, the predictive accuracy significantly increased to 0.71 (95% CI, 0.66-0.75; P=.02). The addition of severe thinness to PSI and hypoalbuminemia further increased the accuracy significantly to 0.74 (95% CI, 0.70-0.78) (P=.005). PRINCIPAL CONCLUSIONS: Severe thinness (BMI<16 kg/m2) was associated with 30-day mortality in patients with CAP, showing improved prognostic performance when combined with PSI. We propose that physicians consider a patient's nutritional state using BMI when predicting mortality in CAP.