Frailty Index Based On Laboratory Data Predicts The Incidence Of Sepsis In The Elderly Inpatients With CAP

Objective:To investigate whether a frailty index based on Laboratory data(laboratory frailty index,FI-LAB)can be used as a predictor of sepsis(including septic shock)in elderly inpatients with community-acquired pneumonia(CAP).Methods:This study was a single-center retrospective cohort study involving patients with community-acquired pneumonia aged≥65 years who were admitted to the Respiratory and critical Care departments of the Fifth People’s Hospital of Chengdu from December 2020 to March 2021.According to the principle of creating frailty index,40 common laboratory and vital signs variables first collected within 24 hours after admission were included to construct FI-LAB.According to previous studies,patients with FI-LAB≥0.35 were defined as frail,while<0.35 was defined as non-frail in this study.The mianoutcomes were sepsis and septic shock during hospitalization.The results were statistically analyzed using SPSS 26.0.The Kolmogorov-Smirnov test was used to assess the normality of distribution.Continuous variables were expressed as the means±SD(standard deviation)or interquartile range(IQR)and compared using Student’s t-test or the Mann-Whitney U test.Categorical variable results were expressed as count(percentage)and were compared using the χ2 test or Fisher’s exact test.Univariate and multivariate modified Poisson regression adjusted for all significant variables were used instead of logistic regression to estimate adjusted or unadjusted relative risk.Receiver operating characteristic(ROC)curves were calculated to estimate the area under the ROC curve(AUC)for FI-LAB in relation to sepsis and septic shock.We applied the Youden index method to determine the optimal cutoffs of FI-LAB for predicting sepsis and septic shock.Results:1.A total of 418 CAP inpatients(60.5%male,median age:74 years old),of whom 130(31.1%)presented with frailty,94(22.5%)developed sepsis,and 42(10.0%)developed septic shock.The median FI-LAB of the cohort was 0.25(0.18,0.38).288 were classified into the non-frail group,with a median FI-LAB of 0.25(0.16,0.28).130(31.1%)were classified into the frail group,whose median FI-LAB was 0.43(0.38,0.50).The in-hospital mortality rate of the whole cohort was 3.8%,including 10 deaths in the frail group and 6 deaths in the non-frail group.2.The modified Poisson regressionanalysis showed that frailtywas a risk factor for sepsis in elderly inpatients with CAP(adjusted Relative Risk[aRR]=3.48,95%confidence interval[CI]:2.13-5.67,P<0.001).Each 0.01 increase in FI-LAB value significantly increased the risk of sepsis by 6%(aRR=1.06,95%CI:1.04-1.07,P<0.001).Moreover,the modified Poisson regression analysis showed that frailty was a risk factor for septic shock in elderly CAP inpatients(aRR=2.36,95%CI:1.02-5.44,P=0.045).Each 0.01 increase in FI-LAB value significantly increased the risk of septic shock by 6%(aRR=1.06,95%CI:1.03-1.08,P<0.001).3.Receiver Operating Characteristic(ROC)curve analysis showed that the area under the curve of FI-LAB for predicting sepsis and septic shock were 0.87(95%CI:0.82-0.91,P<0.001)and 0.85(95%CI:0.79-0.91,P<0.001),the best cutoff value were 0.30 and 0.36,the sensitivity were 83.0%and 73.8%,the specificity were 74.1%and 79.8%,the positive likelihood ratio were 3.20 and 3.65,the negative likelihood ratio were 0.23 and 0.33.Conclusion:1.The frailty CAP inpatients were more complicated with chronic congestive heart failure,stroke history,hypertension,diabetes,tumor and other basic diseases;2.The incidence of altered mental status and pleural effusion were higher in the frailty group than in the non-frailty group;4.The score ofCURB-65 was higher in the frailty group than in the non-frailty group;4.Frailty increases the risk of CAP complicated with sepsis and septic shock;5.FI-LAB can predict the risk of sepsis and septic shock in elderly CAP inpatients.