关键词: 肾功能不全, 肺部感染, 肺疾病, 老年人, 预后

Abstract: Background　Lung infections mostly occur in the elderly， often in the form of comorbidities. Studies have shown that kidney function may affect the prognosis of patients with lung infections， but the mechanism of microbial changes in these patients still remains unclear，and there are few relevant reports in China. Objective　To investigate the relationship of specific etiological susceptibility and altered immune function with poor prognosis in elderly pulmonary infection patients with different estimated glomerular filtration rate. Methods　This retrospective，controlled and observational study was conducted with a cohort of elderly patients（over 65 years old）who were hospitalized due to pulmonary infection in the Second Medical Center，PLA General Hospital from January 2017 to December 2019. General conditions（gender and age），past medical history（chronic kidney disease，diabetes，dyslipidemia，chronic heart failure），and biochemical parameters detected after admission，including blood urea nitrogen（BUN），serum creatinine（Scr），aspartate aminotransferase（AST），alanine aminotransferase（ALT），serum albumin，estimated glomerular filtration rate（eGFR），routine blood parameters〔hemoglobin，white blood cell count，percentage of neutrophils，percentage of lymphocytes，total platelet count，neutrophil to lymphocyte ratio（NLR）〕and pathogenic microbes detected by sputum culture，as well as outcome（survival or death）acquired by a 90-day follow-up were collected. Multivariate Logistic regression analysis was used to explore the associated factors of death. ROC analysis of eGFR in predicting death was performed，and its optimal cut-off value was used to divide the cases into two groups〔eGFR≥47 ml•min-1•（1.73 m2）-1 and eGFR < 47 ml•min-1•（1.73 m2）-1〕 to compare intergroup differences in the distribution of pathogenic microbes and inflammatory indicators. Results　The prevalence of in-hospital death was 13.2%（68/514）. The deceased had younger mean age，lower prevalence of chronic kidney disease，higher mean levels of BUN，Scr，AST，ALT，white blood cell count and NLR，and lower mean levels of albumin，eGFR，hemoglobin and percentage of lymphocytes than survivors（P<0.05）. Multivariate Logistic regression analysis showed that age 〔OR=1.092，95%CI（1.027，1.162）〕，ALT 〔OR=1.013，95%CI（1.001，1.026）〕，albumin level〔OR=0.814，95%CI（0.759，0.873）〕，eGFR 〔OR=0.974，95%CI（0.961，0.988）〕，WBC count 〔OR=1.116，95%CI（1.030，1.210）〕and lymphocyte percentage 〔OR=0.011，95%CI（0，0.521）〕were associated with all-cause death（P<0.05）. The AUC of eGFR in predicting death was 0.614，with 47 ml•min-1•（1.73 m2）-1 was determined as the optimal cutoff value with 36.8% sensitivity，and 84.3% specificity. Compared to patients with eGFR≥47 ml•min-1•（1.73 m2）-1，those with eGFR<47 ml•min-1•（1.73 m2）-1 had higher prevalence of infection with Klebsiella pneumoniae，Escherichia coli，Staphylococcus aureus，and fungi and lower prevalence of infection with Pseudomonas aeruginosa（P<0.05）. Moreover，they also had higher mean percentage of neutrophils and NLR，as well as lower mean percentage of lymphocytes and platelet count（P<0.05）. Conclusion　Changes in immune function and susceptibility to Staphylococcus aureus infections in patients with low eGFR may be underlying causes of worsening prognosis in elderly people with pulmonary infection and reduced renal function.

Key words: Renal insufficiency, Pneumonia, Lung diseases, Aged, Prognosis