a total of 146 consecutive patients ( 292 lower limbs ) , referred to the physiology department for doppler ultrasound evaluation of pad , were prospectively included in the study .
risk factors were self reported by the patient , and biological values were found in medical files .
the lower limbs were classified as clinically normal when skin was normal and both dorsalis pedis and posterior tibialis pulses were present .
doppler measurement and two - dimensional ultrasound examination were conducted by a single investigator ( c.c . ) , using the toshiba powervision 7000 10-mhz linear probe .
two - dimensional images and doppler interrogation were obtained for iliac to ankle arteries and the abdominal aorta .
stenoses were evaluated with the ratio of the maximal systolic velocity at stenosis to the systolic velocity proximal to the stenosis .
osc - abi was measured with an automatic device ( dynamap 8100 , critikon , little chalfont , buckinghamshire , u.k . ) by nurses or clinical staff .
systolic blood pressure was measured with the cuff placed above the ankles for both legs and both arms .
nurses or clinical staff were taught to measure osc - abi , i.e. , to install the cuff with the sampling area facing the ankle artery , namely posterior , and anterior tibial artery for ankle measurement and brachial artery .
dop - abi was measured by a single investigator ( c.c . ) with a continuous wave doppler device ( md2 , 8-mhz probe , huntleigh , luton , u.k . ) .
abi was computed as the ratio of ankle blood pressure to the highest brachial systolic blood pressure for both osc - abi and dop - abi .
costs of procedures were derived from the french medical care system fees for doppler ultrasound examination or abi measurement , combined with a visit with a cardiologist , a general practitioner , or a nurse .
qualitative and quantitative variables were compared using  and student 's t tests , respectively .
the level of agreement between osc - abi and dop - abi was assessed both by correlation analysis using pearson 's correlation coefficient and by a bland - altman plot ( 13 ) .
receiver operating characteristic ( roc ) curves were computed as well as areas under roc curves using proc logistic ; curve areas were compared using a nonparametric approach ( 14 ) implemented in an sas macro for correlated data or a wald test ( 15 ) . positive predictive value ( ppv ) and negative predictive value ( npv ) were computed .
the positive likelihood ratio was computed as the probability of true positive over the probability of false positive , and the negative likelihood ratio was computed as the probability of false negative over the probability of true negative .
doppler measurement and two - dimensional ultrasound examination were conducted by a single investigator ( c.c . ) , using the toshiba powervision 7000 10-mhz linear probe .
two - dimensional images and doppler interrogation were obtained for iliac to ankle arteries and the abdominal aorta .
stenoses were evaluated with the ratio of the maximal systolic velocity at stenosis to the systolic velocity proximal to the stenosis .
osc - abi was measured with an automatic device ( dynamap 8100 , critikon , little chalfont , buckinghamshire , u.k . ) by nurses or clinical staff .
systolic blood pressure was measured with the cuff placed above the ankles for both legs and both arms .
nurses or clinical staff were taught to measure osc - abi , i.e. , to install the cuff with the sampling area facing the ankle artery , namely posterior , and anterior tibial artery for ankle measurement and brachial artery .
dop - abi was measured by a single investigator ( c.c . ) with a continuous wave doppler device ( md2 , 8-mhz probe , huntleigh , luton , u.k . ) .
abi was computed as the ratio of ankle blood pressure to the highest brachial systolic blood pressure for both osc - abi and dop - abi .
costs of procedures were derived from the french medical care system fees for doppler ultrasound examination or abi measurement , combined with a visit with a cardiologist , a general practitioner , or a nurse .
qualitative and quantitative variables were compared using  and student 's t tests , respectively .
the level of agreement between osc - abi and dop - abi was assessed both by correlation analysis using pearson 's correlation coefficient and by a bland - altman plot ( 13 ) .
receiver operating characteristic ( roc ) curves were computed as well as areas under roc curves using proc logistic ; curve areas were compared using a nonparametric approach ( 14 ) implemented in an sas macro for correlated data or a wald test ( 15 ) . positive predictive value ( ppv ) and negative predictive value ( npv ) were computed .
the positive likelihood ratio was computed as the probability of true positive over the probability of false positive , and the negative likelihood ratio was computed as the probability of false negative over the probability of true negative .
diabetic patients had microvascular disease with nephropathy ( 34.6% ) , retinopathy ( 35.8% ) , and neuropathy ( 48.1% ) or macrovascular disease ( 40.7% ) including coronary artery disease , pad , stroke , or carotid stenosis .
pad was clinically suspected because of the absence of distal artery pulses in 54% of nondiabetic patients and 40% of diabetic patients .
pad was diagnosed with dop - abi in 33% of nondiabetic patients and 27% of diabetic patients .
doppler ultrasound examination showed at least one arterial stenosis in 41.7% of the legs in diabetic patients and in 50.8% of the legs in nondiabetic patients . a proximal localization ( i.e. , iliac or femoral artery ) was more frequent in nondiabetic than in diabetic patients ( 37.7 and 5.2% of the localizations , respectively , p < 0.0001 ) , who had more distal localization ( 72.0 vs. 20.8% of the localizations in nondiabetic patients , p = 0.0004 ) .
population characteristics data are means  sd ( range ) or n ( % ) .
* p < 0.05 with t test comparison of means or  test comparison of frequencies .
dop - abi was measurable in 98% of the total population studied ( 97% of diabetic and 99.2% of nondiabetic patients ) , whereas osc - abi was obtained in 95.5% of the legs in the whole population ( p = 0.16 for comparison of techniques ) , in 95.8% of diabetic patients , and in 95.3% of nondiabetic patients .
when osc - abi was not measurable , dop - abi was either not measurable or < 0.90 in most patients ( 9 of 13 legs ) .
osc - abi was related to dop - abi ( r = 0.53 , p < 0.0001 ) in the total population , as well as in nondiabetic patients and in diabetic patients ( fig .
bland - altman representation showed that dop - abi and osc - abi were in good agreement in a wide range of values , and the difference did not vary with the average values in any significant way ( fig .
the mean difference between the two methods was 0.0207  0.27 in the total population , 0.028  0.25 in diabetic patients , and 0.0098  0.28 in nondiabetic patients .
relationship between dop - abi and osc - abi in nondiabetic ( a ) ( r = 0.60 ; p < 0.0001 ) and diabetic ( b ) ( r = 0.49 ; p < 0.0001 ) patients .
c : bland - altman representation of doppler and oscillometric measurement of abi in the whole population and the 95% limit of agreement to the mean difference .
roc curves constructed for osc - abi with dop - abi 0.90 defining pad ( fig .
areas under the curve ( aucs ) of roc curves were not different in diabetic and nondiabetic patients ( auc 0.83 and 0.844 , respectively , p = 0.66 ) .
the best cutoff value for optimal sensitivity and specificity was 1.02 in the whole population , 1.04 in diabetic patients , and 1.0 in nondiabetic patients ( fig .
roc curves for osc - abi for diagnosis of pad , as defined with dop - abi < 0.90 in the whole population ( a ) , diabetic patients ( b ) , and nondiabetic patients ( c ) .
d : best cutoff determination for maximizing both the sensitivity and the specificity in the whole population , diabetic and nondiabetic patients .  ,
roc curves were constructed for dop - abi and osc - abi with stenosis at ultrasound as the criterion for diagnosis of pad ( fig .
the roc curve analyses showed that dop - abi was better than osc - abi for correctly classifying patients for pad ( aucdop - abi 0.873 , aucosc - abi 0.806 , p = 0.026 ) .
dop - abi performance was equivalent in nondiabetic and diabetic patients ( p = 0.068 for aucs of roc curves ) , whereas osc - abi did not perform as well as dop - abi in diabetic patients ( p = 0.026 for roc auc comparison ) .
roc curves for dop - abi and osc - abi for diagnosis of ultrasound - identified arterial stenosis in the whole population ( a ) , diabetic patients ( b ) , and nondiabetic patients ( c ) .
e : dop - abi best cutoff determination for maximizing both the sensitivity and the specificity in the whole population , diabetic and nondiabetic patients .
 , sensitivity ;    , specificity . the diagnostic accuracy for selected abi thresholds ( table 2 ) showed that the commonly used value of 0.90 has a high specificity but a medium sensitivity in the whole population .
the sensitivity of dop - abi and osc - abi was greater in the nondiabetic population compared with that in diabetic patients .
thus , a threshold value of 0.90 defined a highly specific test at the expense of sensitivity for both dop - abi and osc - abi .
dop - abi and osc - abi presented high ppvs in the total population ( 95.3 and 88.1% , respectively ) but also in diabetic patients ( 92.5 and 83.3% , respectively ) .
conversely , npvs were medium in both the whole population ( 76.1 and 65.9% , respectively ) and diabetic patients ( 74.7 and 66.2% , respectively ) . to optimize the threshold values of abi for screening and diagnosis , respectively ,
figure 3b and c shows that the highest sensitivity and specificity were achieved at cutoff values between 1 and 1.1 for both dop - abi and osc - abi in patients with or without diabetes .
diagnostic performance of dop - abi and osc - abi for diagnosis of ultrasound - identified arterial stenosis in the total population and in nondiabetic and diabetic patients nlr , negative likelihood ratio ; plr , positive likelihood ratio .
according to the french medical care system , the costs of pad screening would be 121  ( 162 us dollars [ usd ] ) with a vascular ultrasound study only or 66  ( 88 usd ) with abi only by a cardiologist , 43  ( 58 usd ) with abi only by a general practitioner , and 33  ( 44 usd ) with abi only by a nurse .
dop - abi was measurable in 98% of the total population studied ( 97% of diabetic and 99.2% of nondiabetic patients ) , whereas osc - abi was obtained in 95.5% of the legs in the whole population ( p = 0.16 for comparison of techniques ) , in 95.8% of diabetic patients , and in 95.3% of nondiabetic patients .
when osc - abi was not measurable , dop - abi was either not measurable or < 0.90 in most patients ( 9 of 13 legs ) .
osc - abi was related to dop - abi ( r = 0.53 , p < 0.0001 ) in the total population , as well as in nondiabetic patients and in diabetic patients ( fig .
bland - altman representation showed that dop - abi and osc - abi were in good agreement in a wide range of values , and the difference did not vary with the average values in any significant way ( fig .
the mean difference between the two methods was 0.0207  0.27 in the total population , 0.028  0.25 in diabetic patients , and 0.0098  0.28 in nondiabetic patients .
relationship between dop - abi and osc - abi in nondiabetic ( a ) ( r = 0.60 ; p < 0.0001 ) and diabetic ( b ) ( r = 0.49 ; p < 0.0001 ) patients .
c : bland - altman representation of doppler and oscillometric measurement of abi in the whole population and the 95% limit of agreement to the mean difference .
roc curves constructed for osc - abi with dop - abi 0.90 defining pad ( fig .
areas under the curve ( aucs ) of roc curves were not different in diabetic and nondiabetic patients ( auc 0.83 and 0.844 , respectively , p = 0.66 ) .
the best cutoff value for optimal sensitivity and specificity was 1.02 in the whole population , 1.04 in diabetic patients , and 1.0 in nondiabetic patients ( fig .
roc curves for osc - abi for diagnosis of pad , as defined with dop - abi < 0.90 in the whole population ( a ) , diabetic patients ( b ) , and nondiabetic patients ( c ) .
d : best cutoff determination for maximizing both the sensitivity and the specificity in the whole population , diabetic and nondiabetic patients .  ,
roc curves were constructed for dop - abi and osc - abi with stenosis at ultrasound as the criterion for diagnosis of pad ( fig .
the roc curve analyses showed that dop - abi was better than osc - abi for correctly classifying patients for pad ( aucdop - abi 0.873 , aucosc - abi 0.806 , p = 0.026 ) .
dop - abi performance was equivalent in nondiabetic and diabetic patients ( p = 0.068 for aucs of roc curves ) , whereas osc - abi did not perform as well as dop - abi in diabetic patients ( p = 0.026 for roc auc comparison ) .
roc curves for dop - abi and osc - abi for diagnosis of ultrasound - identified arterial stenosis in the whole population ( a ) , diabetic patients ( b ) , and nondiabetic patients ( c ) .
e : dop - abi best cutoff determination for maximizing both the sensitivity and the specificity in the whole population , diabetic and nondiabetic patients .
the diagnostic accuracy for selected abi thresholds ( table 2 ) showed that the commonly used value of 0.90 has a high specificity but a medium sensitivity in the whole population .
the sensitivity of dop - abi and osc - abi was greater in the nondiabetic population compared with that in diabetic patients .
thus , a threshold value of 0.90 defined a highly specific test at the expense of sensitivity for both dop - abi and osc - abi .
dop - abi and osc - abi presented high ppvs in the total population ( 95.3 and 88.1% , respectively ) but also in diabetic patients ( 92.5 and 83.3% , respectively ) .
conversely , npvs were medium in both the whole population ( 76.1 and 65.9% , respectively ) and diabetic patients ( 74.7 and 66.2% , respectively ) . to optimize the threshold values of abi for screening and diagnosis , respectively ,
figure 3b and c shows that the highest sensitivity and specificity were achieved at cutoff values between 1 and 1.1 for both dop - abi and osc - abi in patients with or without diabetes .
diagnostic performance of dop - abi and osc - abi for diagnosis of ultrasound - identified arterial stenosis in the total population and in nondiabetic and diabetic patients nlr , negative likelihood ratio ; plr , positive likelihood ratio .
according to the french medical care system , the costs of pad screening would be 121  ( 162 us dollars [ usd ] ) with a vascular ultrasound study only or 66  ( 88 usd ) with abi only by a cardiologist , 43  ( 58 usd ) with abi only by a general practitioner , and 33  ( 44 usd ) with abi only by a nurse .
automated oscillometric abi measurement by clinical assistants with little formal training was shown to be feasible in most patients , including diabetic patients .
the diagnostic efficiency was close to that of dop - abi in nondiabetic as well as in diabetic patients , as validated against ultrasound .
furthermore , we defined threshold values for osc - abi measurement as a screening or diagnostic test for pad in nondiabetic and diabetic patients .
our study showed that dop - abi and osc - abi were significantly related , as previously reported in several studies ( 11,12,16 ) .
both methods were limited in some patients ( 0.6% of the legs in our population ) when lower limb arteries were not compressible .
we also described , for the first time , evaluation of the use of the oscillometric method in diabetic patients .
indeed , we showed that osc - abi was obtained in most diabetic patients and related to dop - abi .
furthermore , the low rate of failure for osc - abi ( 1.3% of diabetic patients ) showed that most arteries could be evaluated with this method .
the availability of an automated oscillometric method in diabetic subjects is of particular interest because pad is frequently associated with few clinical symptoms ( 10 ) .
indeed , we validated both dop - abi and osc - abi against ultrasound as a reference and osc - abi against dop - abi as a reference in diabetic patients and established threshold values for detection of artery stenosis .
the analysis of roc curves showed that dop - abi was slightly better than osc - abi in diabetic patients . despite this difference
, osc - abi could represent an alternative method for abi measurement , even in diabetic patients , with the benefit that this method is more readily available than doppler measurement .
our study further extended the evaluation of dop - abi and osc - abi as a diagnostic or a screening test . setting
the threshold at 0.90 led to a ppv > 95% and a threshold of 1.1 led to an npv > 99% ( 1719 ) . in our study ,
dop - abi showed a similar ppv ( 95% ) at a threshold of 0.90 but a lower npv ( 76% ) with a threshold of 1.1 .
this result may be related to differences in the populations studied : the relatively smaller size of our population and higher - risk patients .
we demonstrated similar results with osc - abi and dop - abi in the same patients , with ppv and npv that were 10% lower in the diabetic subpopulation . despite this difference
, the diagnostic accuracy of osc - abi remained high enough to conclude that it could help in pad assessment in diabetic patients .
indeed , pad is frequent in diabetic patients , despite missing or confounding clinical symptoms , because of its coexistence with neuropathy ( 10 ) .
thus , the use of osc - abi as a routine test could improve pad diagnosis and management of lower limb complications in diabetes ( 8) . further , we established threshold values of abi optimized for a screening purpose .
the roc curves showed that both dop - abi and osc - abi could be used for screening for arterial stenosis with a cutoff set at 1.0 to 1.1 , which identified > 80% of the patients with pad whatever the technique used and the presence or absence of diabetes .
these results were in agreement with those reported for dop - abi with a normal value between 1 and 1.2 ( 2,5,17,20 ) .
obstacles to adopting abi measurement for pad diagnosis in primary care were identified previously as time , cost , and the need for a dedicated device and operator skill ( 6,7,12 ) .
in contrast , we have demonstrated that osc - abi can be easily performed by clinical assistants , i.e. , nurses or others , after minimal training and with commonly available devices ( 2,7 ) .
this approach represents substantial savings of costs and time , with a significant improvement in the diagnosis and management of pad in the general population and particularly in diabetic patients .
our study was not designed for cost - effectiveness evaluation ; however , we showed that the use of osc - abi , as first - line screening for pad , would reduce by 61 and 75% the use of vascular studies for pad diagnosis ( 25 of 63 nondiabetic patients and 21 of 83 diabetic patients ) . in patients in whom
distal artery pulses were not palpable , vascular studies would have been reduced by 24 and 36% in nondiabetic and diabetic patients , respectively .
the reduction of costs ( roughly divided by a factor of 3 ) clearly supports the hypothesis of cost saving in pad diagnosis with the use of osc - abi , as measured by nurses and clinical staff .
moreover , the early recognition of pad would improve the management of lower limb complications and cardiovascular risk factors in the general population , with a further reduction in costs because of early intervention for modifiable cardiovascular risk factors ( 10,21 ) .
nevertheless , the cost - effectiveness of osc - abi needs to be assessed in a study specifically design for that purpose . in summary
, our study showed that osc - abi measurement was feasible for clinical assistants using an automatic blood pressure monitoring device .
this may be a low - cost and effective procedure to improve pad management in at - risk patients , including subjects with diabetes , with early recognition and appropriate counseling for the control of modifiable cardiovascular risk factors .
 objectiveperipheral arterial disease ( pad ) is a prognostic marker in cardiovascular disease . 
 the use of doppler - measured ankle - brachial pressure index ( dop - abi ) for pad diagnosis is limited because of time , required training , and costs . 
 we assessed automated oscillometric measurement of the ankle - brachial pressure index ( osc - abi ) by nurses and clinical staff.research design and methodsclinical staff obtained osc - abi with an automated oscillometric device in 146 patients ( 83 with diabetes ) at the time of dop - abi measurement and ultrasound evaluation.resultsmeasurements were obtained in most legs ( dop - abi 98% ; osc - abi 95.5% ) . 
 dop- and osc - abi were significantly related in diabetic and nondiabetic patients with good agreement over a wide range of values . when dop - abi 0.90 was used as the gold standard for pad , receiver operating characteristic curve analysis showed that pad was accurately diagnosed with osc - abi in diabetic patients . when ultrasound was used to define pad , 
 dop - abi had better diagnostic performance than osc - abi in the whole population and in diabetic patients ( p = 0.026 ) . 
 both methods gave similar results in nondiabetic patients . 
 the cutoff values for the highest sensitivity and specificity for pad screening were between 1.0 and 1.1 . 
 estimation of cost with the french medical care system fees showed a potential reduction by three of the screening procedures.conclusionspad screening could be improved by using osc - abi measured by clinical staff with the benefit of greater cost - effectiveness but at the risk of lower diagnostic performance in diabetic patients . 