Higher serum creatinine paradoxically associated with better survival in AKI
Original article
Cerdá J et al. (2007) In severe acute kidney injury, a higher serum creatinine is paradoxically associated with better patient survival. Nephrol Dial Transplant 22: 2781–2784 PubMed
Small increases in serum creatinine level are associated with marked increases in mortality. Paradoxically, some studies have indicated that higher serum creatinine concentrations are associated with a greater likelihood of survival of patients with acute kidney injury (AKI).
Cerdá and colleagues studied 134 critically ill patients with AKI who required continuous renal replacement therapy (CRRT). Multivariate logistic regression analysis detected a relationship between a higher serum creatinine level on CRRT initiation and improved survival (odds ratio 1.438; 95% CI 1.034–1.999). Adjusting for the degree of preadmission chronic kidney disease (CKD; defined by glomerular filtration rate estimated with the MDRD equation) reduced the significance of the association, and adjusting for disease severity (Liano score) eliminated the association altogether; however, adjusting for nutritional status and fluid volume status had no effect.
The authors propose several possible mechanisms for the association of higher serum creatinine levels with better patient survival in AKI. The hypothesis that is best supported by the current analysis is that patients with pre-existing CKD suffer less-severe acute renal damage before requiring initiation of CRRT in a critical care setting than do people without CKD, and as a result have better survival. They propose three other theories that warrant investigation. Firstly, lower serum creatinine level when CRRT is commenced might indicate fluid overload, which is associated with a poor prognosis in AKI. Secondly, serum creatinine levels might not increase rapidly in AKI patients with fluid overload and a low muscle mass, leading to delayed initiation of CRRT and worse outcomes. Thirdly, higher serum creatinine concentrations (indicative of well-nourished patients with appropriate muscle mass) might indicate better health status.
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Subject areas under which this article appears: Acute renal failure
