Fig 1.
Various physiological and technical issues lead to the exclusion of 578 individuals as listed in the text. In addition, 144 participants had incomplete risk factor profiles, 114 failed to show up at the examination site. Digital copies of brachial artery diameter curves were not available in 623 cases. As discussed later, 5499 processed curves were analyzed. Of these, 4734 had the expected time course of an increase in diameter at least 30 seconds following cuff release preceded by a minimum diameter. This pattern was not seen on the remaining 765 curves where a maximum diameter was not seen starting 20 seconds after cuff release.
Fig 2.
Total brachial artery reactivity (TBAR) after the release of an occlusion cuff inflated for 5 minutes.
The rapidly varying diameter values are raw diameter measurements (green) while the solid smooth lines (red) are the results of curve smoothing. Maximum and minimal brachial artery diameters were made from the smoothed curves. TBAR is the difference between maximum and minimum diameters divided by the minimum diameter and then multiplied by 100%. Visual review of some of the studies showed subjective differences in the responses: (A) a strong decrease in brachial artery diameter followed by a strong maximum; (B) a small decrease in diameter followed by a strong increase; and (C) a marked decrease in diameter followed by a small increase. Equivocal results (D) in 765 instances (765/5499: 13.9%) were due to a failure to detect a minimum diameter in the 20 seconds following cuff release (dotted line) since at least one diameter value within this time window (arrowhead) was greater than subsequent diameters.
Table 1.
Demographics and Framingham risk factors for all participants with brachial artery diameter curves.
Table 2.
Demographics and Framingham risk factors for participants included in the study who had distinct measurable minimal and maximal diameters.
Table 3.
This table shows the results of a multivariable Cox proportional model including total brachial artery reactivity (TBAR) and traditional Framingham risk factors for all participants with complete data as shown in Table 2.
Table 4.
This table shows the effect of adding the median of total brachial artery reactivity to a model with Framingham risk factors and the full participant population shown in Tables 1 and 3.
Table 5.
Results of multivariable Cox proportional hazards models predicting first coronary artery disease event with Total Brachial Artery Reactivity (TBAR) in a model with traditional Framingham risk factors in the participants with brachial artery diameter curves with clear minima and maxima.
Table 6.
Results of a multivariable Cox proportional hazards model predicting first coronary artery disease event stratifying Total Brachial Artery Reactivity (TBAR) above and below the sample median in a model with traditional Framingham risk factors.
Fig 3.
Kaplan-Meier curves showing the likelihood of remaining event free with time.
The curves for the event free survival of all individuals are plotted by quartiles, quartile 1 (Q1) being the lowest and Q4 the largest. The plotted quartiles were -5.18 to 4.16%, 4.16 to 7.78%, 7.87 to 13.02%, and 13.02 to 190.22%.
Table 7.
Results of multivariable Cox proportional hazards models predicting first coronary artery disease event with Total Brachial Artery Reactivity (TBAR) in a model with traditional Framingham risk factors in all participants after accounting for outliers.
Fig 4.
Kaplan-Meier curves showing the likelihood of remaining event free with time for TBAR values after excluding 60 outliers.
The curves for the event free survival of 5423 individuals after excluding outliers are plotted by quartiles, quartile 1 (Q1) being the lowest and Q4 the largest. The TBAR quartiles were 0.0 to 4.13%, 4.13 to 7.79%, 7.79 to 12.81%, and 12.81 to 40.11%.
Fig 5.
Kaplan-Meier curves showing the likelihood of remaining event free with time for TBAR values after excluding 60 outliers, instances of poorly defined maxima and minima, and early events.
The curves for the event free survival of 4659 individuals after excluding outliers are plotted by quartiles, quartile 1 (Q1) being the lowest and Q4 the largest. The TBAR quartiles were 0.0 to 5.75%, 5.76 to 8.95%, 8.95 to 13.9%, and 13.9 to 40.11%.
Table 8.
Mean brachial artery diameter (BAD) and flow mediated dilation (FMD) and standard deviation values for three software tools: Brachial Analyzer (BA), the one used in this study, Funky Work Station (FWS), and the Multi-Ethnic Study of Atherosclerosis (MESA) FMD software tool.
Table 9.
Intra-class correlations coefficients (ICC) and 95% confidence intervals (95% CI) between baseline (BASE) brachial artery diameter (BAD), peak response (PR) BAD, and estimated flow-mediated dilation (FMD) between Brachial Analyzer (BA), Funky Work Station (FWS), and the Multi-Ethnic Study of Atherosclerosis (MESA) FMD software tools.