Prognostic Nutritional Index and Mortality in Pneumonia: A Retrospective Cohort Study in China

Zhengrong Ding^1,2Yunxue He^1,2Xue Guo^1,2Ruirui Feng^1,2Guangqin Ren^1,2Lili Deng^3*Chunjiao Zhou^4*Huali Tang^1,2Zhiwei Li⁵Cong Zhou^1,2Bin Li^1,2Longdan Li^1,2

• ¹Zhongshan Hospital of Traditional Chinese Medicine Affiliated to Guangzhou University of Traditional Chinese Medicine, Zhongshan, China
• ²Zhongshan Hospital of Traditional Chinese Medicine, Zhongshan, China
• ³Guangzhou University of Chinese Medicine, Guangzhou, China
• ⁴The Second Affiliated Hospital of Guangzhou University of Chinese Medicine (Guangdong Provincial Hospital of Chinese Medicine), Guangzhou, China
• ⁵People's Liberation Army Information Engineering University Henan Provincial Key Laboratory of Information Security, Zhengzhou, China

Objective: This study aimed to investigate the association between prognostic nutritional index (PNI) and mortality risk in Chinese patients with pneumonia. Methods: This retrospective cohort study was conducted using a multicenter hospital database of adult patients with pneumonia in China. We analyzed data from 635 patients diagnosed with pneumonia at six secondary and tertiary academic hospitals in China between 1 January 2013 and 31 December 2019. Cox regression analysis was used to compare the mortality rates across the PNI tertiles. Restricted cubic spline (RCS) models, Kaplan-Meier survival analysis and Subgroup Analysis were used to explore the association between PNI and the clinical outcomes of these pneumonia patients. Results: A total of 635 patients were included. In the fully adjusted model, each 1-unit increase in PNI was associated with a 5.0% reduction in 30-day mortality risk (HR = 0.950, 95% CI: 0.929–0.972, p < 0.001) and a 4.5% reduction in 90-day mortality risk (HR = 0.955, 95% CI: 0.934–0.975, p < 0.001). Compared with the lowest PNI tertile (Tertile 1), patients in the highest tertile (Tertile 3) had a 64.5% lower risk of 30-day mortality (HR = 0.335, 95% CI: 0.212–0.594, p < 0.0001) and a 60.6% lower risk of 90-day mortality (HR = 0.394, 95% CI: 0.247–0.627, p < 0.0001). Restricted cubic spline (RCS) analysis further illustrated a consistent inverse relationship between PNI and mortality risk. Additionally, Kaplan–Meier survival curves indicated significantly lower cumulative mortality with higher PNI values. Conclusion: Our investigation identified a significant association between poorer PNI scores and higher mortality in Chinese patients with pneumonia.