Background: Contrast-induced nephropathy (CIN) is a common cause of acute kidney injury. Several preventive therapies for this injury have been tested; however, there is still no consensus on the optimal protocol.
Methods: We performed a systematic search of the National Library of Medicine and the Cochrane Library databases from January 1985 to November 2008 to identify randomized controlled studies examining sodium bicarbonate as a preventive measure for CIN in humans. We also reviewed conference abstracts from cardiology nephrology and radiology meetings from 2004 to 2008. A change in serum creatinine levels defined by an absolute (>or=0.5 mg/dl) or percentage (>or=25%) increase in the serum creatinine level is defined as CIN. The primary outcome measure was the incidence of CIN, and the secondary outcome measures were: change in serum creatinine from baseline, requirement for renal replacement therapy and death.
Results: Seventeen randomized controlled trials have investigated the role of sodium bicarbonate for prophylaxis of CIN. The overall incidence of CIN was 11.3%. Using the results from all 17 studies that compared bicarbonate versus saline, the pooled relative risk of developing CIN was 0.54 (95% CI, 0.36-0.83) in the intervention arm, indicating a significant benefit from sodium bicarbonate. The pooled relative risk of CIN was 0.57 (95% CI, 0.35-0.95) when we analyzed for the studies that compared the effects sodium bicarbonate to NAC on development of CIN. There was no difference in the rates of requirement for renal replacement therapy and death.
Conclusions: The use of sodium bicarbonate appears to reduce the incidence of CIN when compared to other preventive strategies for CIN without a significant difference in the requirement of renal replacement therapy and mortality. There are study heterogeneity and publication biases. Further adequately powered randomized controlled studies are needed to determine whether sodium bicarbonate will reduce the clinically meaningful outcomes (e.g., need for dialysis or death) and optimal hydration strategy in high-risk patients.