Abstract
A multicentre prospective observational study (36 sites in 8 Canadian provinces), imbedded in the CODE-MI trial, had clinical laboratories at these sites test 3 samples (normal, female 99th-percentile, and male 99th-percentile concentrations) monthly for 1 year on 67 instruments, producing 2142 results from 6 distinct troponin assays. Mean differences varied per assay with maximum values being & PLUSMN; 4, & PLUSMN; 8, and & PLUSMN; 9 ng/L for the normal, female 99th-percentile, and male 99th-percentile sample, respectively. Using a pragmatic approach, combining all assays, the maximum analytic result variation was & PLUSMN; 3 ng/L for target concentrations less than 10 ng/L and & PLUSMN; 30% at concen-trations slightly above.