reliable data on which to base conclusions. A major limitation is the lack of an external validation analysis of the risk estimates of the scoring systems proposed in this study. These risk estimation systems should be validated, preferably prospectively, prior to their use in other populations of ACS patients. Due to the sample size, some risk subgroups, especially those at the extremes of the risk scores, were not adequately represented and so risk should be estimated with caution. Finally, because of the lack of data on treatment during
follow-up, the differences observed between groups may have been at least partly due to differences in treatment.