Cystatin C-derived measures of renal function as risk factors for mortality and renal replacement therapy in the critically ill - An analysis of the SWECRIT cohort.

PURPOSE: Assess if cystatin C-derived measures of kidney function are associated with mortality in septic- and non-septic intensive care unit (ICU) patients.

METHODS

Data from adult patients staying >24 h in four ICUs in Sweden from November 2015-December 2018 included. Outcomes were mortality and need for renal replacement therapy (RRT) due to acute kidney injury. Associations between cystatin C-estimated glomerular filtration rate (eGFRcys) and shrunken pore syndrome (SPS) and outcomes were assessed with Cox-regression in unadjusted and analyses adjusted for sex, age, illness severity, chronic kidney disease and creatinine. SPS was defined as a ratio between eGFRcys and eGFRcreatinine <0.6.

RESULTS

In total, 4455 patients were included in the analysis, of which 32 % had sepsis. SPS was present in 7.4 % of the cohort, and 90-day mortality was 30.8 %. In sepsis- and non-sepsis patients, SPS and eGFRcys were associated with 90-day-, 1-year mortality and RRT in unadjusted analyses. In an adjusted analysis, SPS was associated with 1-year mortality in sepsis patients (hazard ratio [HR] 1.4, 95 % CI 1.1-1.9, p = 0.021), and eGFRcys was associated with RRT in both sepsis and non-sepsis patients (HR 3.1, 95 % CI 1.6-6.0, p < 0.001, eGFRcys <20 vs ≥60 ml/min/1.73m2). No other associations between eGFRcys, SPS and mortality were detected in adjusted analyses.

CONCLUSION

Our finding that SPS is more robustly associated with mortality in sepsis patients than in non-sepsis patients suggests that the association between SPS and mortality may depend on underlying pathophysiology. A cystatin C-based estimate of GFR is independently associated with RRT in sepsis and non-sepsis.