BACKGROUND

Augmented renal clearance (ARC) refers to a phenomenon in critically ill patients characterized by increased creatinine clearance. Neurological patients seem to be at higher risk compared with other groups. The epidemiology study of ARC reported in critically ill neurological patients varies substantially with the definitions used and the population evaluated.

OBJECTIVE

We aimed to describe the prevalence of ARC and to explore risk factors in critically ill neurological patients.

METHODS

A retrospective observational study was conducted in a university-affiliated neurocritical care unit (NCCU). Study participants had a serum creatinine concentration (Scr) < 120 μmol/L. Kidney function was assessed by the 24-h creatinine clearance (CL); ARC was defined as CLcr ≥ 120 mL/min/1.73m in women and ≥ 130 mL/min/1.73m in men. The prevalence and clinical characteristics of ARC were evaluated. Multivariate logistic regression analysis was used to assess variables associated with ARC occurrence.

RESULTS

Of the 137 patients, 56.2% were male, and the mean age was 50.2 (17.4) years. ARC was present in 55.5% of the NCCU patients, ranging from 50% in intracranial infection to 75% in patients with spinal lesions. ARC patients have a mean CL159.3 (IQR:139.6-185.2) ml/min/1.73m. Age was the only factor independently associated with ARC (OR 0.996, 95% CI: 0.934-0.999, p = 0.043) in multivariable logistic analysis. Scr (Pearson correlation = -0.477) and cystatin C (Pearson correlation = -0.336) were found to have a negative correlation with ARC with statistically significant effects.

CONCLUSION

ARC is prevalent in critically neurological patients. Age is likely to significantly influence renal clearance in this population, especially as patients with low Scr and cystatin C levels should be given more attention.