Nine RCTs involving 585 participants were included in the review.
There was no statistically significant reduction in the incidence of CIN with the use of theophylline (OR 0.40, 95% CI: 0.14, 1.16, P=0.09), but there was a statistically significant reduction in serum creatinine (-0.17 mg/dL, 95% CI: -0.28, -0.06, P=0.002). There was evidence of statistical heterogeneity in both analyses (P=0.08, P<0.001). CIN requiring dialysis was uncommon and was reported in only 1 case.
Regression analyses on the incidence of CIN showed that more recent and poorer quality studies were associated with greater protective effects of theophylline. No statistically significant influences of clinical factors were detected.
There was no evidence of publication bias, and the pooled results were robust to the addition of new negative trials.