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Allometric scaling of diameter change in the original flow-mediated dilation protocol

2012; Elsevier BV; Volume: 226; Issue: 2 Linguagem: Inglês

10.1016/j.atherosclerosis.2012.11.027

1879-1484

Greg Atkinson, Alan M. Batterham,

Hemodynamic Monitoring and Therapy

The negative correlation between percent flow-mediated dilation (FMD%) and baseline diameter (D(base)) has only recently been recognised as a fundamental ratio-scaling problem, which is not resolved by significance-testing of D(base) inequality between groups/conditions, nor by covariate-adjusting FMD% itself by D(base). It is resolved appropriately by allometric scaling of the relationship between peak diameter (D(peak)) and D(base) using statistical models. Therefore, we extracted data from a seminal study on FMD%, and re-analysed it using allometric methods. We found that D(peak) did not increase as a constant proportion of D(base), rendering FMD% a biased estimator of differences in endothelial function between artery sites (brachial vs femoral) and age-groups (children vs. adults). The allometric expression was D(peak)/D(base)(≈ 0.90), rather than a simple ratio. In agreement with our previous research, a proper allometric perspective on FMD led to unbiased estimates of endothelial function, with full adjustment for the influence of baseline diameter.