Predictive value of serum creatinine/cystatin C in neurocritically ill patients

OBJECTIVE: To explore the predictive value of serum creatinine (Cr) to cystatin C (CysC) ratio in neurocritically ill patients. METHODS: We conducted a retrospectively observational study of adult patients admitted to a neurocritical care unit (NCU) between Jan 2013 and Jan 2017. Patients were excluded if <18 years old, required neurocritical care <72 hr, did operation during hospitalization, had premorbid disability or acute kidney injury (AKI) at admission. The Cr/CysC ratio was obtained at NCU admission. Primary end points were short‐term (30‐day) mortality and long‐term (6‐month) poor outcome, with the latter defined as modified Rankin Scale (mRS) of 4–6. RESULTS: Of 538 eligible patients, the etiology included acute ischemic stroke (N = 193, 35.9%), intracranial hemorrhage (N = 116, 21.6%), encephalitis and/or meningitis (N = 85, 15.8%), and others (N = 144, 26.7%). Serum Cr/CysC ratio was significantly correlated with body mass index (BMI) (r = .161, p < .001), the length of NCU stay (r = −.161, p < .001), duration of mechanical ventilation (r = −.138, p = .001), and risk of tracheotomy (r = −.095, p = .028). During follow‐up, 88 (16.4%), patients died within 30 days and 307 (57.1%) patients achieved good outcome at 6 months. In multivariate logistic regression analysis, we identified serum Cr/CysC ratio as an independent predictor of long‐term functional outcome (OR: 0.989, 95% CI: 0.980–0.998, p = .015) but not 30‐day mortality (p = .513). CONCLUSIONS: Serum Cr/CysC ratio at admission could be used as a predictor of long‐term poor prognosis in neurocritically ill patients.