Figure 4. Subgroup analyses according to the study protocols.

The forest plot shows relative risks (by random effects model) for the incidence of contrast-induced acute kidney injury associated with high-dose statin pre-treatment, compared with control group (low-dose statin or placebo), stratified according to (1) type of intervention, (2) type of contrast agent, (3) mean age of the patients, (4) underlying chronic kidney disease, (5) acute coronary syndrome, (6) N-acetylcystein as concomitant prophylactic measure, and (7) placebo controlled trial or not. Abbreviations: ACS, acute coronary syndrome; CI, confidence intervals; CKD, chronic kidney disease; RR, relative risks.