One core laboratory at two international sites, is that feasible? An inter-core laboratory and intra-observer...

To assess the magnitude of differences in QCA outcomes between two cooperating core laboratories in a single trial, we have carried out an inter-core laboratory variability study. Two QCA experts at the Montreal Heart Institute and Heart Core Leiden both analyzed 32 lesions (pre- and post-intervention) in accordance with previously agreed upon standard operating procedures. One of the experts analyzed the whole image set twice to determine the intraobserver variability. The inter-core laboratory differences in the acute gain (n = 31 pairs) are non-significant. The systematic errors of the individual measurements (n = 63 analyses) show an excellent intraclass correlation coefficient of reliability (>75%), except for the stent length (67.7%). The corresponding random errors are small. In general, the intra-observer systematic and random errors are both slightly smaller than those for the inter-core laboratory study. QCA analyses in clinical trials can be carried out in core laboratories at two different locations if and only if highly standardized conditions are maintained.