Xiangqun Zhang,1,2 Long Yang,1,3,* Junyuan Wu,1,3,* Xue Mei1,2 

1Emergency Medicine Clinical Research Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, People’s Republic of China; 2Clinical Center for Medicine in Acute Infection. Capital Medical University, Beijing, People’s Republic of China; 3Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Junyuan Wu; Xue Mei, Email wu007838@sina.com; meixue91@yeah.net

Background: Community-acquired pneumonia (CAP) is a significant global health issue, leading to high morbidity and mortality rates. Despite the existence of various severity scoring systems, accurately predicting patient outcomes remains challenging. The CAP-PIRO (Predisposition, Insult, Response, and Organ dysfunction) scoring system offers a comprehensive approach to evaluating CAP severity and prognosis.
Objective: This study aimed to assess the effectiveness of the CAP-PIRO scoring system in predicting the prognosis and severity of CAP patients, focusing on the development of acute respiratory distress syndrome (ARDS) and 28-day mortality.
Methods: A total of 875 CAP patients were prospectively enrolled from the emergency department of Beijing Chao-yang Hospital between November 2017 and December 2023. Clinical data, including patient demographics, medical history, vital signs, and laboratory findings, were collected within 6 hours of admission. CAP-PIRO, CURB-65, and PSI scores were calculated. Patients were stratified based on ARDS development, 28-day mortality, and PaO2/FiO2 categories (≤ 100 mmHg, 100– 200 mmHg, 200– 300 mmHg).
Results: Significant differences were observed in PCT, blood lactate (Lac), CURB-65, PSI, and CAP-PIRO scores between patients with and without ARDS, as well as between survivors and non-survivors at 28 days (P< 0.05). CAP-PIRO and Lac were identified as independent predictors for ARDS development and 28-day mortality. The area under the ROC curve (AUC) for CAP-PIRO was higher than that for CURB-65 and PSI in predicting 28-day mortality. The combination of CAP-PIRO and Lac demonstrated improved predictive accuracy for ARDS. Notably, significant differences in CAP-PIRO scores were observed across different PaO2/FiO2 groups.
Conclusion: CAP-PIRO demonstrates strong predictive ability for adverse outcomes and, when combined with lactate, shows enhanced predictive power. These findings underscore the value of CAP-PIRO for clinical risk stratification in CAP patients.

Keywords: CAP, CAP-PIRO scoring system, prognosis prediction, ARDS, risk stratification