Cystatin C and Derived Measures of Renal Function As Risk Factors for Mortality and Acute Kidney Injury in Sepsis - A Post-Hoc Analysis of the FINNAKI Cohort

Purpose: To assess the association between cystatin C-derived estimates of kidney function and mortality and acute kidney injury (AKI) in sepsis.Materials and methods: Post-hoc analysis of sepsis patients in the FINNAKI-cohort (n = 802). Primary outcome was 90-day mortality. We measured plasma cystatin C and creatinine at intensive care unit (ICU) admission and estimated glomerular filtration rates (eGFRcys, eGFRcrea) and shrunken pore syndrome (SPS; defined as eGFRcys/eGFRcrea ratio < 0.7). Associations were assessed using Cox-or logistic regression.Results: Increased cystatin C and decreased eGFRcyswere associated with mortality in unadjusted analyses and in analyses adjusted for illness severity and creatinine. Hazard ratios (HRs) in unadjusted analyses were 3.30 (95% CI; 2.12-5.13, p < 0.001) and 3.26 (95% CI; 2.12-5.02, p < 0.001) respectively. SPS was associated with mortality in an unadjusted-(HR 1.78, 95% CI; 1.33-2.37, p < 0.001) and in an adjusted analysis (HR 1.54, 95% CI; 1.07-2.22, p = 0.021). All cystatin C-derived measures were associated with mortality also after adjustment for AKI devel-opment. Cystatin C was associated with AKI in unadjusted analyses but not in analyses adjusted for creatinine.Conclusion: Cystatin C and derived measures of kidney function at ICU admission are associated with an increased 90-day mortality. Increased AKI incidence does not fully explain this association.(c) 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).