Sodium bicarbonate could reduce nephropathy risk

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Sodium bicarbonate-based hydration was found to be superior to normal saline for reducing the risk of contrast-induced nephropathy (CIN) in high-risk patients exposed to iodinated contrast, according to a meta-analysis published online May 13 in BMC Medicine.

CIN is the leading cause of in-hospital acute renal failure, and can lead to increased morbidity, mortality and health costs. Ensuring adequate hydration prior to contrast exposure is highly effective at preventing this complication, although the optimal hydration strategy to prevent CIN still remains an unresolved issue, according to the authors.

Pascal Meier, MD, from the University of Michigan School of Medicine in Ann Arbor, and colleagues said that the study's objective was to assess the effectiveness of normal saline versus sodium bicarbonate for prevention of contrast-induced nephropathy. The researchers pooled a total of 17 randomized, controlled trials including 2,633 subjects, until Dec. 15, 2008.

The investigators found 109 cases of CIN in 1,327 patients who received sodium bicarbonate hydration, compared with 175 cases in 1,306 patients treated with saline. The difference translated into an odds ratio for CIN of 0.52 in favor of sodium bicarbonate.

The authors calculated that the number needed to treat to prevent one case of contrast-induced nephropathy was 16.

They said that there were no significant differences in the rates of post-procedure hemodialysis (P=0.20) or death (P=0.53). Also, the benefits of sodium bicarbonate diminished somewhat in patients undergoing elective procedures but remained statistically significant (odds ratio, 0.63).

However, the authors noted that it "remains unclear whether there is a dose effect and whether alkalinization is the underlying beneficial mechanism."

Based on their findings, the authors concluded there is a "significant benefit of using sodium bicarbonate-based hydration for prophylaxis of CIN although the magnitude of the benefit may have been overestimated by earlier studies. However, the lack of any study to date showing superiority of saline-based hydration suggests that sodium bicarbonate-based hydration should be considered the optimal hydration in high-risk patients undergoing exposure to iodinated contrast."