Fourteen RCTs (n=1,261) were included.
There was a statistically significant reduction in contrast-induced nephropathy with acetylcysteine compared with control, with an overall OR of 0.54 (95% CI: 0.32, 0.91, P=0.022). However, significant statistical heterogeneity was identified across the studies (P=0.032). There was no statistically significant difference in serum creatinine levels between treatment groups, with an overall difference between groups of -7.2 micromol/L (95% CI: -19.7, 5.3, P=0.26). However, significant statistical heterogeneity was identified (P<0.0005).
The investigation by meta-regression suggested that the heterogeneity could be partially explained by whether the angiographs were elective or emergency procedures. The ORs were found to be lower in those studies with elective angiographs than in those including emergency procedures (P=0.06). According to the meta-regression, patient age, baseline serum creatinine levels, volume of contrast media, diabetes mellitus, or any of the study quality criteria did not account for the heterogeneity observed. The Jadad quality scores assigned to the individual studies ranged from 1 to 5, with 9 studies scoring 4 or 5. The authors stated that the result of the Begg's test (P=0.03) and Egger's test (P=0.09) suggested possible publication bias.