Eight retrospective observational studies were included (211,162 participants in contrast agent groups and 5,078,666 in the non-contrast group).
Three studies reported no mortalities. In five studies the incidence of all-cause mortality was 0.34% in the contrast group and 0.9% in the control group; there was no statistically significant difference between the two groups (OR 0.57, 95% CI 0.32 to 1.01, I2=92%).
Four studies reported on myocardial infarction. The incidence was 0.15% in the contrast group and 0.2% in the control group; there was no statistically significant difference between the two groups (OR 0.85, 95% CI 0.35 to 2.05, I2=66%).
Sensitivity analyses that investigated removal of individual studies and differing follow-up times showed no statistically significant differences between contrast and control groups for mortality and myocardial infarction for all analyses.
The incidence of anaphylactic reaction was 0.004% and incidence of allergic reaction was 0.009% in the contrast agents groups (110,500 participants).
Funnel plot showed no evidence of publication bias.