Comparison of procalcitonin, a potentially new inflammatory biomarker of frailty, to interleukin-6 and C-reactive protein among older Chinese hospitalized patients.

AIM: Procalcitonin (PCT) has predictive value for patients with infectious diseases, but has not been studied in frailty. The purpose of this study was to compare PCT to two other inflammatory biomarkers [interleukin-6 (IL-6)] and C-reactive protein (CRP) in their association with frailty among older hospitalized patients.

METHODS: Retrospective study of inpatients (June-December, 2016), who had all three biomarkers measured within 24 h of admission. Frailty was defined according to the Chinese version of a validated frailty scale. Due to the association of biomarkers with infection, we divided patients into "non-infected" (no pneumonia or other infections) and "pneumonia" (using standard criteria) groups.

RESULTS: Of 435 patients (mean age 81.6 ± 8.6 years), 181 (41.6%) were designated the non-infected group and 254 (58.4%) the pneumonia group. Prevalence of frailty in the non-infected group was 32.0% (58/181) and frailty (univariate analysis) was associated with higher PCT and IL-6 levels but not CRP. Prevalence of frailty in the pneumonia group was 40.2% (102/254) and frailty was associated with all three biomarkers. In multivariable analysis adjusting for age, gender, smoking, alcohol use, hemoglobin, albumin, neutrophils and creatinine, PCT (not IL-6 and CRP) was associated with frailty in the non-infected group (OR = 5.244; 95% CI, 1.622-16.947; P = 0.006) and none of the biomarkers were associated with frailty in the pneumonia group.

CONCLUSIONS: Although the study is limited due to the retrospective methods, PCT but not IL-6 or CRP, was associated with frailty among older inpatients without infection. None of these biomarkers were associated with frailty among patients with pneumonia.