MIDAS is a double-blind, randomized, controlled clinical trial comparing the effects of isradipine with hydrochlorothiazide on the rate of changes in the progression of carotid intima media thickness in 883 asymptomatic primary hypertensives having ultrasonographic evidence of at least one uncomplicated carotid lesion. Estimates of carotid intima media thickness (IMT), a surrogate measure of atherosclerosis, are obtained with B-Mode ultrasound in the common, bifurcation, and internal carotid arteries, bilaterally. Examinations are performed at baseline and once every 6 months for 36 months. Major surrogate endpoints for atherosclerosis include severity, expressed as the Single Maximum IMT (Tmax) among the 12 arterial sites, and combined extent and severity, which is the overall Mean Maximum IMT (MeanMax) over 12 sites. Defining the reproducibility of outcome measurements is a primary objective in studies aimed at establishing whether medical intervention is effective in slowing the progression of atherosclerosis. In MIDAS baseline and final examinations, together with a randomly selected 20% quota of follow-up scans and readings, were blindly replicated. Examinations have been replicated on 878 of the 883 patients enrolled into the study. Baseline consistency of the measurements are presented as the mean arithmetic and absolute differences between two examinations and readings. The mean arithmetic and absolute differences for the MeanMax were -0.003 ± 0.156 and 0.12 mm, respectively. Variabilities were comparable for several other atherosclerosis endpoints with the greatest mean absolute difference noted for the Tmax (0.36 mm). Reproducibility of the intra- and intersonographer and reader performances ranged between 0.09 and 0.12 mm (absolute differences). There were not statistically significant differences between replicate examinations for any endpoint or for any measure of variability. These data show that measurements of IMT are highly consistent.
|Original language||English (US)|
|Number of pages||16|
|Journal||Journal of Cardiovascular Diagnosis and Procedures|
|State||Published - Dec 1 1993|
ASJC Scopus subject areas
- Medicine (miscellaneous)
- Cardiology and Cardiovascular Medicine