Abstract:【Objective】To investigate the association of lower respiratory tract infection with PCT (Procalcitonin),CRP (c-reactive protein) and AAG (αl acid glycoprotein) in geriatric patients with COPD.【Methods】Clinical profiles of 84 geriatric patients with COPD admitted to our hospital from January 2018 to December 2021 were retrospectively analysed. Lower respiratory tract infection stauts age,gender,BMI,comorbidity,blood lipid index,chronic obstructive pulmonary disease prevention and treatment (GOLD) grade,coagulation index,and level of PCT,CRP and AAG were collected. Multivariate logistic regression analysis was used to analyze the independent risk factors of lower respiratory tract infection in elderly patients with COPD; Spearman test was used to analyze the correlation of lower respiratory tract infection with PCT,CRP and AAG in elderly patients with COPD. 【Results】Among 84 elderly patients with COPD,50 patients (59.52%) were admitted as uninfected group with no lower respiratory tract infection and 34 patients (40.48%) were admitted to the infection group with lower respiratory tract infection. There was no statistically significant difference in age,gender,comorbidities,blood lipid indicators,BMI,coagulation indicators,GOLD grading,smoking history,and disease course between the two groups (P>0.05). The levels of PCT,CRP,and AAG in the infection group were higher than those in the non-infection group (P<0.05). Multivariate logistic regression analysis showed that CRP,PCT and AAG were independent risk factors for lower respiratory tract infection in elderly patients with COPD (P<0.05). Spearman test showed that serum levels of PCT,CRP and AAG were positively correlated with lower respiratory tract infection in elderly patients with COPD (P<0.05). 【Conclusion】PCT,CRP and AAG are the risk factors for lower respiratory tract infection in geriatric patients with COPD. With the increase of PCT,CRP and AAG levels,the risk of lower respiratory tract infection in elderly patients with COPD increases accordingly.