Abstract:Objective To analyze the predictive value of the levels of interleukin（IL）-6 and high mobility group box 1 protein（HMGB1） in bronchoalveolar lavage fluid（BALF） for the condition and prognosis of elderly patients with severe community acquired pneumonia（SCAP）. Methods A total of 120 elderly patients with community-acquired pneumonia（CAP） treated in the Second Affiliated Hospital of Xinjiang Medical University from March 2019 to March 2022 were selected and divided into mild group（n=72） and severe group（n=48） according to the severity of the disease.The bronchoalveolar lavage（BAL） with fiberbronchoscope was performed in both groups. According to the prognosis after 3 months follow-up, the severe group was divided into survival subgroup（n=36） and death subgroup（n=12）. The levels of IL-6, IL-10, HMGB1, procalcitonin（PCT） and hypersensitive C-reactive protein（hs-CRP） in BALF were detected and compared between mild group and severe group, survival subgroup and death subgroup to analyze the relationships between clinical indicators and clinical pulmonary infection score（CPIS）, and the relationship between the BALF indicators and the prognosis of elderly patients with SCAP. The diagnostic efficacy of IL-6 and HMGB1 levels in the prognosis of patients with SCAP was judged by the receiver operating characteristic（ROC） curve. Results The levels of IL-6, HMGB1, PCT and hs-CRP in BALF in severe group and in death subgroup were significantly higher than those in mild group and in survival subgroup,respectively（P＜0.05）, while the levels of IL-10 in severe group and in death subgroup significantly reduced compared with that in mild group and in survival subgroup,respectively（P＜0.05）. The levels of IL-6, HMGB1 and PCT in BALF of SCAP patients were positively correlated with CPIS score（P＜0.05）, and negatively correlated with IL-10（P＜0.05）. Multivariate logistic regression analysis showed that the higher levels of IL-6（OR=2.553, P=0.028） and HMGB1（OR=2.981, P=0.021） in BALF were the risk factors for the poor prognosis of SCAP patients. ROC curve analysis showed that the optimal cut-off point of IL-6 and HMGB1 for predicting the poor prognosis of elderly patients with SCAP was 91.5pg/mL and 58.6μg/L, respectively. The combined prediction efficiency was the best, with AUC of 0.865, sensitivity of 89.9% and specificity of 80.3%. Conclusion The detection of IL-6 and HMGB1 in BAL has high value in evaluating the condition and prognosis of the elderly patients with SCAP.