Objective To investigate the expression and prognostic value of serum antimicrobial peptide LL37 and human soluble scavenger receptor cysteine-rich domain-containing protein(SSC5D)in elderly patients with chronic heart failure(CHF).Methods A total of 100 CHF patients admitted to Suzhou Kowloon Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from January 2017 to January 2022 were selected as the CHF group.According to the prognosis,these patients were divided into good group(n=60)and poor prognosis group(n=40).Another 100 healthy examinees were selected as the control group.Enzyme-linked immunosorbent assay was used to detect serum levels of LL37 and SSC5D.The differences in serum LL37 and SSC5D levels between CHF group and control group were compared.Spearman correlation analysis was used to analyze the correlation between serum LL37 and SSC5D.Kaplan-Meier survival curve was used to analyze the relationship between serum LL37 and SSC5D expression and the prognosis of CHF patients.COX regression analysis was used to analyze the factors affecting the prognosis of CHF patients.ROC curve was used to analyze the predictive value of serum LL37 and SSC5D for poor prognosis in elderly CHF patients.Result The levels of serum LL37(771.38±158.25 ng/ml)and SSC5D(15 789.35±1 306.25 pg/ml)in CHF group were higher than those in control group(526.23±115.58 ng/ml,8 938.72±858.29 pg/ml),and the differences were significant(t=12.510,43.830,all P＜0.001).Spearman correlation analysis showed that there was a significant positive correlation between serum LL37 and SSC5D in CHF patients(r=0.629,P＜0.001).The serum LL37 and SSC5D levels in CHF patients were positively correlated with NYHA cardiac function classification(r=0.776,0.751,all P＜0.001).The survival rate of the high-level LL37 group was lower than that of the low-level LL37 group(38.18％vs 86.67％),and the difference was significant(Log rankx2=24.242,P＜0.001).The survival rate of the high level SSC5D group was lower than that of the low level SSC5D group(37.74％vs 85.10％),and the difference was significant(Log rank x2=23.291,P＜0.001).Compared with the good prognosis group,the poor prognosis group had a higher proportion of patients over 70 years old,proportion of patients with NYHA cardiac function class Ⅲ+Ⅳ,and serum LL37 and SSC5D levels,and the differences were significant(x2=10.774,4.118,t=4.723,14.059,all P＜0.05).Multivariate COX analysis showed that age＞70 years(OR=1.515,95％CI:1.224～1.858),NYHA cardiac function class Ⅲ+Ⅳ(OR=1.236,95％CI:1.198～1.963),high level of LL37(OR=1.705,95％CI:1.163～2.582)and high level of SSC5D(OR=1.591,95％C1:1.052～1.916)were independent risk factors for the prognosis of CHF patients.ROC curve analysis showed that the area under the curve of serum LL37 combined with SSC5D for predicting poor prognosis of CHF in the elderly was larger than that of serum LL37 and SSC5D alone,and the differences were significant(Z=2.834,2.168,P=0.005,0.030).Conclusion The serum LL37 and SSC5D levels are increased in patients with CHF,and both are risk factors for poor prognosis in patients with CHF,which can be used as clinical indicators to evaluate the prognosis of CHF.