Four RCTs were included (n=573). Sample size ranged from 59 to 219. In all studies, losses to follow-up were less than 10%. Two studies had adequate allocation concealment and none were blinded. Studies were judged to be at moderate risk of bias.
Isotonic sodium bicarbonate was associated with a statistically significant reduction in the risk of an incremental rise in serum creatinine concentration greater than 25% above the baseline (relative risk 0.22, 95% CI: 0.11 to 0.44, p<0.0001). No significant heterogeneity was found (I2=0%).
Isotonic sodium bicarbonate was associated with a significant increase in urinary pH (weighted mean difference 0.98, 95% CI: 0.83 to 1.13, p<0.00001) and a significant protective effect on the absolute change in serum creatinine concentration (weighted mean difference -9.4 μmol/L (95% CI: -17.2 to -1.7. p=0.02) and creatinine clearance from baseline (weighted mean difference 3.7 mL/minute, 95% CI: 0.55 to 6.80, p=0.02). Significant heterogeneity was found for the absolute change in creatinine clearance (I2=57%), but not for the other outcomes.
There was no statistically significant difference between treatments in the incidence of acute renal failure requiring dialysis, but its incidence was low (1.4%)
There was no significant difference between isotonic sodium bicarbonate and control in mortality (one study, n=59) or changes in serum potassium (two studies). Only one treatment-related adverse effect was reported (a transient rise in blood pressure).