Application Value Of Serum C-Reactive Protein And Procalcitonin Levels In Guiding The Use Of Antibiotics In Patients With Acute Exacerbation Of Chronic Obstructive Pulmonary Disease And Their Relationships With Lung Function

Purpose:By monitoring the levels of serum C-reactive protein（CRP）and procalcitonin（PCT）in patients with Acute Exacerbation of Chronic Obstructive Lung Disease（AECOPD）during hospitalization,we can guide the use of antibiotics in order to reduce the unnecessary exposure of antibiotics;By exploring the relationships between the levels of serum PCT and CRP in patients with acute exacerbation stage and stable stage of the same lung function grading,find an effective basis for the diagnosis of Acute Exacerbation of Chronic Obstructive Lung Disease（COPD）;By exploring the relationship between different lung functions and serum PCT,CRP levels in patients with acute exacerbation of COPD,and the relationships between serum PCT,CRP levels and PEF and MEF 50%in patients with acute exacerbation of COPD,further evaluate the prognosis of patients.Data and methods:From October 2020 to September 2022,we collected 160 patients with AECOPD who were admitted to the Department of Respiratory Medicine of China-Japan Union Hospital of Jilin University,including 77 males and 83 females.At the same time,we collected the physical examination report data of 40 patients with moderate lung function who had not experienced acute exacerbation of COPD in the same year,including 20 males and 20 females.The diagnosis of COPD and AECOPD conform to the diagnostic criteria in the《Guidelines for the Diagnosis and Treatment of Chronic Obstructive Lung Disease（2019）》.Exclusion criteria:（1）Patients complicated with lung and other parts infection,bronchial asthma,acute trauma,serious cardio-cerebrovascular disease,blood disease,rheumatic immune system disease,etc.（2）Patients received other antibiotics,intravenous and oral glucocorticoids 14 days before admission.（3）There was a history of immunosuppressive use within 180 days before admission.（4）Pregnant and lactating women.On the basis of routine treatment,160 patients with AECOPD were randomly divided into four groups:PCT group,CRP group,PCT combined with CRP group,and control group.In the control group,the using or discontinuation of antibiotics should be based on the patients of clinical symptoms and signs recommended in the《Guidelines for the Diagnosis and Treatment of Chronic Obstructive Lung Disease（2019）》（（1）Three essential symptoms:aggravation of dyspnea,increased sputum volume and purulent sputum;（2）two essential symptoms including purulent sputum;（3）invasive or non-invasive mechanical ventilation treatment is required）.The levels of serum PCT and CRP in all groups were tested on the 1st,3rd,5th,7th and 10th day of admission respectively,and the use or discontinuation use of antibiotics was determined according to the levels of serum PCT and CRP.The standard of antibiotics can be used in PCT group:when the level of serum PCT≥0.1μg/L,antibiotics should be used for treatment,and patients should stop using antibiotics until PCT<0.1μg/L;The standard of antibiotics can be used in CRP group:when the level of CRP≥50 mg/L,patients should be treated with antibiotics,and patients should stop using antibiotics until CRP<50 mg/L;The standard of antibiotics can be used in PCT combined with CRP group:when the level of serum PCT≥0.1μg/L and the level of serum CRP≥50 mg/L,patients should be treated with antibiotics,and patients should stop using antibiotics until the level of serum PCT<0.1μg/L and/or CRP<50 mg/L.The cut-off point of bacterial infection and antibiotics use determined by the level of serum PCT≥0.1μg/L^[1],and the cut-off point of bacterial infection and antibiotics use determined by the level of serum CRP≥50mg/L^[2].Record the antibiotics use rate,the number of using antibiotics days,therapeutic effect,secondary infection of patients（the number of cases of secondary infection is determined by the patients of clinical symptoms and signs,the results of sputum culture,G test,GM test,chest CT）,hospitalization time,hospitalization cost,etc.,and compare and analyze them in four groups.Patients of PCT group,CRP group,PCT combined with CRP group would took lung function examination after treatment and the clinical symptoms and signs were significantly relieved.The degree of airflow restriction was divided according to the percentage of FEV1 to the predicated value:FEV1%≥80%was mild airflow restriction;50%≤FEV1%<80%was moderately airflow restriction;30%≤FEV1%<50%was severely airflow restriction;FEV1%<30%was extremely severe airflow restriction.The patients with moderate airflow limitation were included in the study group,and 40 patients with stable stage of COPD who took physical examination were included in the control group.The levels of serum PCT and CRP tested on the first day after admission in the study group were compared with those in the control group.In order to facilitate the study,in PCT group,CRP group and PCT combined with CRP group,75 patients with mild and moderate airflow restriction were classified as group A,and 45 patients with severe and extremely severe airflow restriction were classified as group B.The levels of serum PCT and CRP tested on the first day after admission of the two groups were compared and analyzed.The lung function examination results of patients with AECOPD were recorded,and the results of PEF and MEF 50%were compared with the levels of serum PCT and CRP tested on the first day after admission.Results:1.There was no significant difference in age,sex,smoking index,onset time,temperature,and therapeutic effect between PCT group,CRP group,PCT combined with CRP group and control group（all P>0.05）.2.The antibiotics use rate and the number of using antibiotics days of PCT group,CRP group and PCT combined CRP group were lower than control group and the differences were statistically significant（all P<0.05）;The antibiotics use rate and the number of using antibiotics days of PCT combined with CRP group were lower than PCT group and CRP group,and the differences were significant（all P<0.001）;The antibiotics use rate of CRP group was higher than PCT group,and the difference was not statistically significant（P>0.05）;The number of using antibiotics days of CRP group was more than PCT group,but the difference was not statistically significant（P>0.05）.3.The secondary infection of patients,hospitalization time and hospitalization cost of PCT group,CRP group and PCT combined with CRP group were lower than control group（all P<0.05）;The hospitalization time and hospitalization cost of PCT combined with CRP group were lower than PCT group and CRP group,and the differences were statistically significant（all P<0.001）;The hospitalization time of CRP group was lower than that of PCT group,and the difference was not statistically significant（P>0.05）;The hospitalization cost of CRP group was higher than PCT group,but the difference was not statistically significant（P>0.05）;There was no significant difference in the rate of secondary infection between PCT combined with CRP group,CRP group and PCT group（P>0.05）.4.Among the patients with AECOPD,120 patients in PCT group,CRP group and PCT combined with CRP group were re-grouped according to the degree of airflow restriction,51 patients with moderate airflow restriction were included in the study group,and 40 patients with moderate airflow restriction and COPD without acute attack within one year were included in the control group.The average age of patients in the study group was 77.90±10.63（years old）,including 22 women and 29men;The average age of patients in the control group was 78.15±10.56（years old）,with 20 females and 20 males.There was no significant difference in age and sex between the two groups（all P>0.05）.Compared with the control group,the levels of serum CRP and PCT tested on the first day after admission in the study group were significantly higher than those in the control group（all P<0.05）.5.In order to facilitate the study,in PCT group,CRP group and PCT combined CRP group,75 patients with mild and moderate lung function airflow restriction were classified as group A,and 45 patients with severe lung function airflow restriction and extremely severe airflow restriction were classified as group B.There was no significant difference in age and sex between the two groups（all P>0.05）.The levels of serum PCT and CRP tested on the first day after admission in the two groups were compared and analyzed.The levels serum of PCT and CRP in group A were significantly lower than those in group B（all P<0.05）,and the difference was statistically significant.6.By Spearman analysis,the level of serum CRP tested on the first day after admission of patients with AECOPD was significantly correlated with PEF（correlation coefficient r=-0.44）,MEF 50%（correlation coefficient r=-0.73）,both of them were negatively correlated（all P<0.001）.The level of serum PCT was significantly correlated with PEF（correlation coefficient r=-0.67）and MEF 50%（correlation coefficient r=-0.95）,both of them were negatively correlated（all P<0.001）.Conclusions:1.By dynamic monitoring the levels of serum CRP and PCT can help to assess the infection degree of patients with AECOPD in time,guide the use of antibiotics in patients with AECOPD,so as to reduce unnecessary using of antibiotics,shorten the number of using antibiotics days,shorten the hospitalization time,and reduce the hospitalization cost and patients’secondary infection.2.The levels of serum PCT and CRP in patients with AECOPD and moderate airflow restriction are significantly higher than those patients with COPD in stable stage,which can assist in the diagnosis of acute exacerbation as early as possible.3.The worse the lung function of patients with COPD,the more severe the infection in the acute exacerbation period.