Measurement reliability of cardiovascular reactivity change scores: a comparison of intermittent and continuous methods of assessment.

Cardiovascular reactivity testing is a widely used measure of risk for hypertension and coronary heart disease. Evidence for the reliability of the measures, however, is weak. If the measures (usually change scores) are unreliable, the usefulness of testing is limited, since relationships with other measures, such as disease outcomes, may be obscured. This study examines the reliability of blood pressure change, using both a traditional method of assessment (Colin ABPM) which provides intermittent readings, and a non-invasive method that samples the complete distribution of pressures (Ohmeda Finapres). While the reliability for the Colin was found to be good for absolute level of individual measurements, it was extremely poor for change scores. The Finapres, however, yielded high reliabilities for change scores as well as absolute levels, due to the large number of readings taken during baseline and stressor conditions. Implications for reactivity testing methodology are discussed.