Abstract 2059: Differences between Site-Reported and Core Laboratory Creatine Kinase-MB Values in an International Clinical Trial: Results from the SYNERGY Trial
Background: Geographical variability in clinical practice and the lack of standardized CK-MB assays have potentially limited the congruency of CK-MB measurements in large international trials. We analyzed correlations between site-reported CK-MB values and their corresponding values from a core laboratory in the SYNERGY trial.
Methods: In SYNERGY 12 countries enrolled pts, and in 5 predetermined countries, a separate study sample of every cardiac enzyme level drawn by a site investigator was sent to a SYNERGY core lab. All samples were converted to the ratio of the measure/ULN to normalize the measures. We calculated correlations between the site and the core lab value for each time-based matched record of CK-MB.
Results: 913 pts had CK-MB results from the core lab, with a total of 4,693 time-based matched lab values between the core lab and site-reported values. 708 (15%) CK-MB values were greater than twice the ULN in the core lab (diagnostic range for MI endpoint), but less than twice the ULN reported by the corresponding site lab. There was only a moderate overall correlation (Kappa =0.45), but a trend for core lab values to be greater than site reported values. Using the core lab measures, 162 pts had an endpoint MI. Based on the site values, only 72 (44%) of these same patients were identified as having had an endpoint MI at any time during the hospitalization.
Conclusion: There is a considerable amount of variation in CK-MB values between sites and a core laboratory in this study. Importantly, these differences in lab values have potential impact on identification of clinical endpoints so further understanding of why the lab values are discrepant is desperately needed.