Relationship Between the Prognostic Nutritional index and Short-Term Prognosis among Patients with Community-Acquired Bacterial Pneumonia: A Retrospective Analysis of the MIMIC-IV

The objective of this study was to investigate the association between the prognostic nutritional index (PNI) and the short-term outcomes in patients with community-acquired bacterial pneumonia (CABP). This study employed a retrospective design, utilizing data from the Medical Information Mart for Intensive Care (MIMIC)-IV database. 371 individuals from the MIMIC-IV database who were diagnosed with CABP. The primary endpoint was 28-day all-cause mortality. The secondary endpoint was the length of stay (LOS) in the intensive care unit (ICU) and in hospital. The area under the curve of PNI for predicting 28-day all-cause mortality is 0.702 (95% CI 0.630 to 0.775; p < 0.001). Patients were divided into two groups based on their PNI at admission: the low PNI (<35.75) group and the high PNI group (≥35.75). CABP patients with higher PNI presented a lower 28-day all-cause mortality rate (adjusted HR: 0.53, 95% CI 0.28-0.98, p = 0.044). Moreover, a negative linear correlation was found between the PNI and short-term mortality rates via restricted cubic splines. Eventually, there was no difference in the LOS in the ICU or hospital between the two groups. These findings suggest a negative correlation between the PNI at admission and the short-term mortality rate of CABP. PNI is helpful for early identification of high-risk patients.