Serum Cystatin C for Prediction of Dialysis Requirement or Death in Acute Kidney Injury: A Comparative Study
Received 4 April 2009; accepted 9 June 2009. published online 07 August 2009.
Background
Serum cystatin C has emerged as a new and potentially more reliable marker of kidney function. However, its utility and performance in patients with acute kidney injury (AKI), particularly for the prediction of dialysis requirement, is not well known.
Study Design
Prospective cohort study.
Settings & Participants
Adult patients with AKI enrolled at 2 academic medical centers, at time of nephrology consultation.
Predictors
Serum cystatin C (primary predictor), serum creatinine, and serum urea nitrogen levels and 24-hour urine output measured at enrollment.
Outcomes
The composite of dialysis requirement or in-hospital death.
Covariates
Acute Physiology and Chronic Health Evaluation II (APACHE II) score, liver disease, sepsis, and mechanical ventilation.
Results
200 participants were enrolled for this analysis. Mean age was 65 years, 55% were men, and mean APACHE II score was 20. In unadjusted analyses, increases in serum cystatin C (odds ratio [OR], 1.87; 95% confidence interval [CI], 1.36 to 2.59), serum creatinine (OR, 1.53; 95% CI, 1.12 to 2.09), and serum urea nitrogen levels (OR, 1.84; 95% CI, 1.34 to 2.54) were associated with a higher odds (per 1-SD increase) for the composite outcome, whereas greater urine output (OR, 0.56; 95% CI, 0.39 to 0.80) was associated with lower odds. These associations persisted after adjustment for APACHE II score. The addition of serum cystatin C, serum creatinine, and serum urea nitrogen levels or urine output to a basic model entailing APACHE II score, liver disease, sepsis, and assisted mechanical ventilation improved its prediction, evidenced by increases in areas under a receiver operator characteristic curve from 0.816 to 0.829, 0.826, 0.837, and 0.836, respectively. However, there was no significant difference between each of these models.
Limitations
Observational study, single serum cystatin C measurement.
Conclusion
In patients with AKI, serum cystatin C level performs similarly to serum creatinine level, serum urea nitrogen level, and urine output for predicting dialysis requirement or in-hospital death. Larger studies are needed to confirm these findings.
Drs Perianayagam and Seabra contributed equally to this article.
Because an author of this manuscript is an editor for AJKD, the peer-review and decision-making processes were handled entirely by an Associate Editor (Russell Chesney, MD, University of Tennessee Health Science Center) who served as Acting Editor-in-Chief. Details of the journal's procedures for potential editor conflicts are given in the Editorial Policies section of the AJKD website.
ABSTRACT