Changes in serum creatinine in the first 24 hours after cardiac arrest indicate prognosis: an observational cohort study

INTRODUCTION: As patients after cardiac arrest suffer from the consequences of global ischemia reperfusion, we aimed to establish the incidence of acute kidney injury (AKI) in these patients, and to investigate its possible association to severe hypoxic brain damage. METHODS: One hundred and seventy-one patients (135 male, mean age 61.6 +/- 15.0 years) after cardiac arrest were included in an observational cohort study. Serum creatinine was determined at admission and 24, 48 and 72 hours thereafter. Serum levels of neuron-specific enolase (NSE) were measured 72 hours after admission as a marker of hypoxic brain damage. Clinical outcome was assessed at intensive care unit (ICU) discharge using the Pittsburgh cerebral performance category (CPC). RESULTS: AKI as defined by AKI Network criteria occurred in 49% of the study patients. Patients with an unfavourable prognosis (CPC 3-5) were affected significantly more frequently (P = 0.013). Whilst serum creatinine levels decreased in patients with good neurological outcome (CPC 1 or 2) over the ensuing 48 hours, it increased in patients with unfavourable outcome (CPC 3-5). ROC analysis identified DeltaCrea24 <-0.19 mg/dl as the value for prediction with the highest accuracy. The odds ratio for an unfavourable outcome was 3.81 (95% CI 1.98-7.33, P = 0.0001) in cases of unchanged or increased creatinine levels after 24 hours compared to those whose creatinine levels decreased during the first 24 hours. NSE levels were found to correlate with the change in serum creatinine in the first 24 hours both in simple and multivariate regression (both r = 0.24, P = 0.002). CONCLUSIONS: In this large cohort of patient after cardiac arrest, we found that AKI occurs in nearly 50% of patients when the new criteria are applied. Patients with unfavourable neurological outcome are affected more frequently. A significant association between the development of AKI and NSE levels indicating hypoxic brain damage was observed. Our data show that changes in serum creatinine may contribute to the prediction of outcome in patients with cardiac arrest. Whereas a decline in serum creatinine (> 0.2 mg/dL) in the first 24 hours after cardiac arrest indicates good prognosis, the risk of unfavourable outcome is markedly elevated in patients with constant or increasing serum creatinine.