Steigen Terje K, Claudio Cheryl, Abbott David, Schulzer Michael, Burton Jeff, Tymchak Wayne, Buller Christopher E, John Mancini G B
Cardiovascular Imaging Research Core Laboratory, Division of Cardiology, Vancouver Hospital, 3300-950 W. 10th Avenue, Vancouver, BC, Canada V5Z 4E3.
Int J Cardiovasc Imaging. 2008 Jun;24(5):453-62. doi: 10.1007/s10554-007-9285-x. Epub 2007 Dec 12.
To assess reproducibility of core laboratory performance and impact on sample size calculations.
Little information exists about overall reproducibility of core laboratories in contradistinction to performance of individual technicians. Also, qualitative parameters are being adjudicated increasingly as either primary or secondary end-points. The comparative impact of using diverse indexes on sample sizes has not been previously reported.
We compared initial and repeat assessments of five quantitative parameters [e.g., minimum lumen diameter (MLD), ejection fraction (EF), etc.] and six qualitative parameters [e.g., TIMI myocardial perfusion grade (TMPG) or thrombus grade (TTG), etc.], as performed by differing technicians and separated by a year or more. Sample sizes were calculated from these results. TMPG and TTG were also adjudicated by a second core laboratory.
MLD and EF were the most reproducible, yielding the smallest sample size calculations, whereas percent diameter stenosis and centerline wall motion require substantially larger trials. Of the qualitative parameters, all except TIMI flow grade gave reproducibility characteristics yielding sample sizes of many 100's of patients. Reproducibility of TMPG and TTG was only moderately good both within and between core laboratories, underscoring an intrinsic difficulty in assessing these.
Core laboratories can be shown to provide reproducibility performance that is comparable to performance commonly ascribed to individual technicians. The differences in reproducibility yield huge differences in sample size when comparing quantitative and qualitative parameters. TMPG and TTG are intrinsically difficult to assess and conclusions based on these parameters should arise only from very large trials.
评估核心实验室检测性能的可重复性及其对样本量计算的影响。
与个体技术人员的表现相比，关于核心实验室整体可重复性的信息较少。此外，定性参数越来越多地被判定为主要或次要终点。此前尚未报道使用不同指标对样本量的比较影响。
我们比较了由不同技术人员进行的、间隔一年或更长时间的对五个定量参数[如最小管腔直径（MLD）、射血分数（EF）等]和六个定性参数[如TIMI心肌灌注分级（TMPG）或血栓分级（TTG）等]的初次和重复评估结果。根据这些结果计算样本量。TMPG和TTG也由另一个核心实验室进行判定。
MLD和EF的可重复性最高，计算得出的样本量最小，而直径狭窄百分比和中心线壁运动则需要规模大得多的试验。在定性参数中，除TIMI血流分级外，所有参数的可重复性特征得出的样本量都需要数百名患者。TMPG和TTG在核心实验室内部和之间的可重复性仅为中等水平，这突出了评估这些参数存在的内在困难。
核心实验室可被证明能提供与通常归因于个体技术人员的表现相当的可重复性表现。在比较定量和定性参数时，可重复性差异会导致样本量出现巨大差异。TMPG和TTG本质上难以评估，基于这些参数得出的结论仅应来自非常大规模的试验。
