ABI data collected to date

464 participants have data entered.

Here are the distributions of numbers of participants by age, and by race and poverty status separately by sex.

Are we getting consistent measures?

Left arm correlations

          lArmSys1 lArmSys2 lArmSys2A
lArmSys1   1.00     0.91***  0.91*** 
lArmSys2   0.91***  1.00     0.91*** 
lArmSys2A  0.91***  0.91***  1.00    

n
          lArmSys1 lArmSys2 lArmSys2A
lArmSys1       464      463       460
lArmSys2       463      463       460
lArmSys2A      460      460       460

Right arm correlations

          rArmSys1 rArmSys1A rArmSys2
rArmSys1   1.00     0.80***   0.80***
rArmSys1A  0.80***  1.00      0.94***
rArmSys2   0.80***  0.94***   1.00   

n
          rArmSys1 rArmSys1A rArmSys2
rArmSys1       464       463      462
rArmSys1A      463       463      462
rArmSys2       462       462      462

Left ankle posterior and dorsal correlations

            lAnkPosSys1 lAnkPosSys2 lAnkDorSys1 lAnkDorSys2
lAnkPosSys1  1.00        0.87***     0.82***     0.82***   
lAnkPosSys2  0.87***     1.00        0.77***     0.83***   
lAnkDorSys1  0.82***     0.77***     1.00        0.85***   
lAnkDorSys2  0.82***     0.83***     0.85***     1.00      

n
            lAnkPosSys1 lAnkPosSys2 lAnkDorSys1 lAnkDorSys2
lAnkPosSys1         463         462         462         458
lAnkPosSys2         462         462         462         458
lAnkDorSys1         462         462         463         458
lAnkDorSys2         458         458         458         458

Right ankle posterior and dorsal correlations

            rAnkPosSys1 rAnkPosSys2 rAnkDorSys1 rAnkDorSys2
rAnkPosSys1  1.00        0.84***     0.75***     0.79***   
rAnkPosSys2  0.84***     1.00        0.78***     0.89***   
rAnkDorSys1  0.75***     0.78***     1.00        0.87***   
rAnkDorSys2  0.79***     0.89***     0.87***     1.00      

n
            rAnkPosSys1 rAnkPosSys2 rAnkDorSys1 rAnkDorSys2
rAnkPosSys1         463         462         463         462
rAnkPosSys2         462         462         462         462
rAnkDorSys1         463         462         463         462
rAnkDorSys2         462         462         462         462

Overall indexes correlations

     rABI     lABI     ABI     
rABI  1.00     0.78***  0.92***
lABI  0.78***  1.00     0.90***
ABI   0.92***  0.90***  1.00   

n =  464 

Consistency accounting for validity

Ngozi reviews ABI data to confirm the validity of the measures. Thus far, there are 6 participants marked invalid and 28 awaiting Ngozi's review.

Diagnoses for participants with valid data:

ABIdx
    Normal Borderline   Moderate  TibialArt     Severe 
       329         54         25         22          0 

Excluding participants with invalid data yields the following correlations:

Left arm correlations

          lArmSys1 lArmSys2 lArmSys2A
lArmSys1   1.00     0.91***  0.91*** 
lArmSys2   0.91***  1.00     0.91*** 
lArmSys2A  0.91***  0.91***  1.00    

n
          lArmSys1 lArmSys2 lArmSys2A
lArmSys1       430      430       428
lArmSys2       430      430       428
lArmSys2A      428      428       428

Right arm correlations

          rArmSys1 rArmSys1A rArmSys2
rArmSys1   1.00     0.79***   0.79***
rArmSys1A  0.79***  1.00      0.94***
rArmSys2   0.79***  0.94***   1.00   

n
          rArmSys1 rArmSys1A rArmSys2
rArmSys1       430       430      429
rArmSys1A      430       430      429
rArmSys2       429       429      429

Left ankle posterior and dorsal correlations

            lAnkPosSys1 lAnkPosSys2 lAnkDorSys1 lAnkDorSys2
lAnkPosSys1  1.00        0.86***     0.82***     0.83***   
lAnkPosSys2  0.86***     1.00        0.77***     0.83***   
lAnkDorSys1  0.82***     0.77***     1.00        0.84***   
lAnkDorSys2  0.83***     0.83***     0.84***     1.00      

n
            lAnkPosSys1 lAnkPosSys2 lAnkDorSys1 lAnkDorSys2
lAnkPosSys1         430         430         430         428
lAnkPosSys2         430         430         430         428
lAnkDorSys1         430         430         430         428
lAnkDorSys2         428         428         428         428

Right ankle posterior and dorsal correlations

            rAnkPosSys1 rAnkPosSys2 rAnkDorSys1 rAnkDorSys2
rAnkPosSys1  1.00        0.87***     0.81***     0.82***   
rAnkPosSys2  0.87***     1.00        0.80***     0.89***   
rAnkDorSys1  0.81***     0.80***     1.00        0.88***   
rAnkDorSys2  0.82***     0.89***     0.88***     1.00      

n =  430 

Overall indexes correlations

     rABI     lABI     ABI     
rABI  1.00     0.82***  0.92***
lABI  0.82***  1.00     0.93***
ABI   0.92***  0.93***  1.00   

n =  430 

Coefficient of variation (CV)

The coefficient of variation is a standardized measure of dispersion (higher values indicate greater dispersion). It is useful for comparing data among studies despite differences in methods.

A wide range of coefficients of variation are reported in the literature. In our data, CV is 12.0%, which is somewhat greater than some published reports, but perhaps not so large for a sample with this much age and demographic variation.

CV varies by demographics but not in an obvious systematic way.

   Sex  Race PovStat  ABI
 Women White   Above  8.9
 Women White   Below 12.6
 Women AfrAm   Above 13.9
 Women AfrAm   Below 12.0
   Men White   Above 10.8
   Men White   Below 15.8
   Men AfrAm   Above 10.4
   Men AfrAm   Below  9.9