Fourteen studies (n=2,320, sample size range 18 to 502) were included in the review (total sample size reported as 2,290 in parts of the review). One study received a Jadad score of 5 points, one study achieved 4 points and the others scored 3 points or fewer. No further study quality details were reported.
CI-AKI: The reviewers presented risk ratios from each study, but did not pool them overall, citing statistical heterogeneity (p=0.02, I2=48%) as the reason. Statistical heterogeneity was largely related to study size. Within a subgroup of the 12 smallest trials (n=1,145), the authors found a pooled risk ratio that favoured bicarbonate over saline (RR 0.50, 95% CI 0.27 to 0.93) in a subgroup with substantial statistical heterogeneity (I2=56%). Within a subgroup of the three largest trials (n=1,175), which had lower statistical heterogeneity I2=0%), the pooled risk ratio was not statistically significant.
A range of other results related to changes in serum creatinine, effect of baseline risk and renal replacement therapy were reported. Sensitivity analyses indicated the results were not significantly affected by any single study. The authors interpreted a funnel plot as indicating some asymmetry and thus risk of publication bias.