Prognostic factors for severe community-acquired pneumonia in high altitude areas.

High altitude and hypoxia may impact the prognosis of critically ill patients. Currently, research on the outcomes of patients with severe community-acquired pneumonia (SCAP) in high-altitude regions remains limited. This study was conducted to determine the 30-day mortality rate and identify associated risk factors in SCAP patients on the Qinghai-Tibet Plateau. We prospectively enrolled 183 adults with SCAP admitted to Lhasa People’s Hospital between 1 January 2023 and 31 December 2024. Patients were divided into survival group and non-survival group based on the survival status within 30 days. Demographic data, clinical features, laboratory indicators, and treatment measures were compared between these two groups. Multivariate Cox regression analysis was used to identify risk factors for 30-day mortality and survival curves were drew in patients with SCAP. Receiver operating characteristic (ROC) curve was used to evaluate the predictive value of relevant risk factors for 30-day mortality, and compare the differences of predictive value among different factors. For model development and validation, the entire cohort was randomly split into a training set (70% of n) and a validation set (30% of n) using a computer-generated random sequence. Among the 183 SCAP patients enrolled, 56 died within 30 days, with a 30-day mortality rate of 30.6%. Multivariate Cox regression analysis showed that age ≥ 65 years (Hazard Ratio [HR] = 1.849, 95% Confidence Interval (CI): 1.012 ~ 3.379, P = 0.046), septic shock (HR = 4.340, 95% CI 1.845 ~ 10.208, P = 0.001), arterial partial pressure of oxygen/fraction of inspired oxygen ratio(P/F ratio) < 150 mmHg (HR = 3.333, 95% CI 1.866 ~ 5.952, P < 0.001), D-dimer > 3.0 mg/L (HR = 1.965, 95% CI 1.044 ~ 3.699, P = 0.036), and unknown etiology (HR = 2.391, 95% CI 1.319 ~ 4.335, P = 0.004) were independent risk factors for 30-day mortality. In the training set (n = 126, 70%), the prediction model integrating these five indicators had a sensitivity of 78.6% and specificity of 82.7% for predicting 30-day mortality (Receiver Operating Characteristic-Area Under the Curve [ROC-AUC] = 0.884, 95% CI 0.829 ~ 0.927, P < 0.001), superior to CURB-65 score (AUC = 0.673), Pneumonia Severity Index (PSI) score (AUC = 0.695), Acute Physiology and Chronic Health Evaluation (APACHE) II score (AUC = 0.783) and Sequential Organ Failure Assessment (SOFA) score (AUC = 0.725). In the validation set (n = 57, 30%), the prediction model had a sensitivity of 80.0% and a specificity of 85.7% for predicting 30-day mortality (AUC = 0.862, 95% CI 0.760 ~ 0.964, P < 0.001), superior to CURB-65 score (AUC = 0.637), PSI score (AUC = 0.571), APACHE II score (AUC = 0.769), and SOFA score (AUC = 0.723). Advanced age (≥ 65 years), septic shock, decreased P/F ratio, elevated plasma D-dimer levels, and unknown etiology are independent risk factors for 30-day mortality in patients with SCAP. The combination of these five risk factors can effectively predict the occurrence of death within 30 days, with a predictive value better than CURB-65 score, PSI score, APACHE II score and SOFA score.