Twenty-four studies (23 cohort studies and one RCT) were included in the review (n=792,740), half of which were prospective. Sample size varied from 44 to 663,635. Methodological quality varied between studies. Twelve studies used systematic surveillance for cardiac complications. Nine studies used blinded outcome assessment. Only six studies were judged as high quality. The follow-up duration ranged from three to 30 days.

__Perioperative cardiac complications (18 studies; n=124,032)__:

The Revised Cardiac Risk Index discriminated moderately well between patients at low risk versus high risk for cardiac events after mixed noncardiac surgery (pooled AUC 0.75, 95% CI 0.72 to 0.79; 10 studies). A moderate statistical heterogeneity (I^{2}=48%) was observed in the pooled outcome. When evaluating the predictive accuracy of the Revised Cardiac Risk Index for classifying patients as low-risk versus intermediate to high-risk, it had a sensitivity of 0.65 (95% CI 0.46 to 0.81), a specificity of 0.76 (95% CI 0.58 to 0.88), a positive likelihood ratio of 2.78 (95% CI 1.74 to 4.45) and a negative likelihood ratio of 0.45 (95% CI 0.31 to 0.67).

The Revised Cardiac Risk Index was less accurate in predicting cardiac events after vascular noncardiac surgery (pooled AUC 0.64, 95% CI 0.61 to 0.68; seven studies). A moderate statistical heterogeneity (I^{2}=29%) was observed in the pooled outcome. When evaluating the predictive accuracy of the Revised Cardiac Risk Index for classifying patients as low-risk versus intermediate to high-risk, it had a sensitivity of 0.70 (95% CI 0.53 to 0.82), a specificity of 0.55 (95% CI 0.45 to 0.66), a positive likelihood ratio of 1.56 (95% CI 1.42 to 1.73) and a negative likelihood ratio of 0.55 (95% CI 0.40 to 0.76).

Sensitivity analyses did not materially affect the results. The authors reported that pooling of AUCs from the total 18 studies was not performed due to high statistical heterogeneity (I^{2}=82%). The random-effects metaregression showed that only the variable of surgery type (vascular noncardiac versus mixed noncardiac) significantly accounted for this heterogeneity (p=0.01).

__Perioperative all-cause mortality (six studies, n=668,708)__:

The Revised Cardiac Risk Index was less accurate in predicting all-cause mortality (median AUC of 0.62, range from 0.54 to 0.78). A pooled AUC was not performed due to high statistical heterogeneity (I^{2}=95%).