Predictive Value Of PCT,SII And FAR For Severity Of Community-Acquired Pneumonia

Objective:To investigate the predictive value of procalcitonin(PCT),systemic immune inflammation index(SII),fibrinogen to albumin ratio(FAR)and combined indicators for the severity of patients with community-acquired pneumonia.Methods:The 193 hospitalized patients with community-acquired pneumonia in the Jiangsu University Affiliated People’s Hospital from December 2020 to December 2022 were analyzed retrospectively.According to the 2016 edition of the guidelines "Guidelines for the Diagnosis and Treatment of Community-Acquired Pneumonia in Chinese Adults",the patients were divided into non-SCAP group(n = 151)and SCAP group(n = 42),and SCAP group again were divided into survival group(n=31)and death group(n=11)according to the outcome of patients during hospitalization.General data and serologic parameters of hospitalized patients were colltected.General clinical data of groups including gender,age,BMI,smoking history,drinking history,length of hospital stay,heat surge,endotracheal intubation,CURB-65 score,respiratory failure,pleural effusion,hypertension,cerebral infarction,diabetes,and history of coronary heart disease were analysed.The difference of serologic parameters including PCT,SII,FAR,blood routine,biochemistry,coagulation function and other serological indicators were statistical significance.Central tendency of PCT,SII,FAR was compared by Boxplot among groups.The interaction of PCT,SII,FAR with age,smoking history,hypertension,cerebral infarction,diabetes mellitus,coronary heart disease,respiratory failure,pleural effusion were showed by Subgroup analysis.The values of PCT,SII,FAR between the non-SCAP group and the SCAP group were compared to each other in different times.ROC curve was used to assess the predictive value of PCT,SII,FAR,and combined indicators for the severity of patients with community-acquired pneumonia,and assess its value for clinical application.Results:(1)Statistical analysis of general data showed that there were significant differences between the non-SCAP and SCAP groups in age,drinking history,length of hospital stay,endotracheal intubation,CURB-65 score,respiratory failure,pleural effusion,cerebral infarction,and history of coronary heart disease(P < 0.05).The age and BMI between the survival and death groups were significant difference(P < 0.05).The age of the survival group significantly were lower than the death group,the BMI higher than the death group.(2)Serological indicators showed that there were significant differences in white blood cell(WBC),neutrophil count(NC),red blood cell distribution width(RDW),albumin(ALB),aspartate aminotransferase(AST),blood urea nitrogen(BUN),lactate dehydrogenase(LDH),prothrombin time(PT),partial prothrombin time(APTT),fibrinogen(FIB),D-dimer(DD),procalcitonin(PCT),SII and FAR between the non-SCAP group and the SCAP group(P < 0.05).The albumin of the SCAP group were significantly lower than the non-SCAP group,and other indicators higher than the non-SCAP group.There were significant difference in blood urea nitrogen(BUN),fibrinogen(FIB),procalcitonin(PCT),SII and FAR between the survival group and the death group(P < 0.05).The urea nitrogen of the death group were lower than the survival group,and other indicators higher than the survival group.(3)The results of Boxplot of PCT,SII and FAR showed that the median values of each index in the SCAP group were higher than the non-SCAP group,and the values of the non-SCAP group were more concentrated(P < 0.05).The median values of each index in the death group were higher than the survival group,and the values of the survival group were more concentrated(P < 0.05).(4)PCT,SII and FAR were compared with groups at different time points.The three indicators on admission and seventh day were higher in the SCAP group than in the non-SCAP group,and the indicators on admission higher than seventh day.The three indicators on admission and seventh day were higher in the death group than in the survival group,and the indicators on admission were higher than seventh day.The differences were statistically significant(P < 0.05).(5)Subgroup analysis showed PCT and FAR were not relative to age,smoking history,hypertension,cerebral infarction,diabetes mellitus,coronary artery disease,respiratory failure,pleural effusion(interaction P value 0.209～0.985).SII was relative to smoking history(interaction P value 0.017)in the SCAP group.(6)The area under the ROC curve shows that the best cut-off value for PCT was 0.15,sensitivity was 97.62%,specificity was 52.98%,P<0.001.The best cut-off value for SII was 1496.50,sensitivity 78.57%,specificity was 72.19%,P<0.001.The best cut-off value for FAR was 0.23,sensitivity was 61.90%,specificity was 87.42%,P<0.001.The best cut-off value for the joint index was 0.12,sensitivity was 90.48%,specificity was 70.20%,P<0.001.(7)The incidence of SCAP predicted by the calibration curve was near to the actual,and there was not significant difference.The goodness of fit was good by the Hosmer-Lemeshow test(P >0.05).The decision curve analysis(DCA)had good clinical application.Conclusions:PCT,SII and FAR had good predictive value for the severity of patients with communityacquired pneumonia,and the combined index was superior to a single predictor,and this prediction model had goodness of fit and clinical utility.