Profound influence of different methods for determination of the ankle brachial index on the prevalence estimate of peripheral arterial disease

BACKGROUND: The ankle brachial index (ABI) is an efficient tool for objectively documenting the presence of lower extremity peripheral arterial disease (PAD). However, different methods exist for ABI calculation, which might result in varying PAD prevalence estimates. To address this question, we compared five different methods of ABI calculation using Doppler ultrasound in 6,880 consecutive, unselected primary care patients ≥65 years in the observational getABI study. METHODS: In all calculations, the average systolic pressure of the right and left brachial artery was used as the denominator (however, in case of discrepancies of ≥10 mmHg, the higher reading was used). As nominators, the following pressures were used: the highest arterial ankle pressure of each leg (method #1), the lowest pressure (#2), only the systolic pressure of the tibial posterior artery (#3), only the systolic pressure of the tibial anterior artery (#4), and the systolic pressure of the tibial posterior artery after exercise (#5). An ABI < 0.9 was regarded as evidence of PAD. RESULTS: The estimated prevalence of PAD was lowest using method #1 (18.0%) and highest using method #2 (34.5%), while the differences in methods #3–#5 were less pronounced. Method #1 resulted in the most accurate estimation of PAD prevalence in the general population. Using the different approaches, the odds ratio for the association of PAD and cardiovascular (CV) events varied between 1.7 and 2.2. CONCLUSION: The data demonstrate that different methods for ABI determination clearly affect the estimation of PAD prevalence, but not substantially the strength of the associations between PAD and CV events. Nonetheless, to achieve improved comparability among different studies, one mode of calculation should be universally applied, preferentially method #1

Peripheral Arterial Disease as an Independent Predictor for Excess Stroke Morbidity and Mortality in Primary-Care Patients: 5-Year Results of the getABI Study

Background:There is controversial evidence with regard to the significance of peripheral arterial disease (PAD) as an indicator for future stroke risk. We aimed to quantify the risk increase for mortality and morbidity associated with PAD. Methods:In an open, prospective, noninterventional cohort study in the primary care setting, a total of 6,880 unselected patients ≧65 years were categorized according to the presence or absence of PAD and followed up for vascular events or deaths over 5 years. PAD was defined as ankle-brachial index (ABI) <0.9 or history of previous peripheral revascularization and/or limb amputation and/or intermittent claudication. Associations between known cardiovascular risk factors including PAD and cerebrovascular mortality/events were analyzed in a multivariate Cox regression model. Results:During the 5-year follow-up [29,915 patient-years (PY)], 183 patients had a stroke (incidence per 1,000 PY: 6.1 cases). In patients with PAD (n = 1,429) compared to those without PAD (n = 5,392), the incidence of all stroke types standardized per 1,000 PY, with the exception of hemorrhagic stroke, was about doubled (for fatal stroke tripled). The corresponding adjusted hazard ratios were 1.6 (95% confidence interval, CI, 1.1–2.2) for total stroke, 1.7 (95% CI 1.2–2.5) for ischemic stroke, 0.7 (95% CI 0.2–2.2) for hemorrhagic stroke, 2.5 (95% CI 1.2–5.2) for fatal stroke and 1.4 (95% CI 0.9–2.1) for nonfatal stroke. Lower ABI categories were associated with higher stroke rates. Besides high age, previous stroke and diabetes mellitus, PAD was a significant independent predictor for ischemic stroke. Conclusions:The risk of stroke is substantially increased in PAD patients, and PAD is a strong independent predictor for stroke.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

Prevalence estimates for PAD using different methods for ABI calculation

<p><b>Copyright information:</b></p><p>Taken from "Profound influence of different methods for determination of the ankle brachial index on the prevalence estimate of peripheral arterial disease"</p><p>http://www.biomedcentral.com/1471-2458/7/147</p><p>BMC Public Health 2007;7():147-147.</p><p>Published online 6 Jul 2007</p><p>PMCID:PMC1950873.</p><p></p> PAD was defined by an ABI value < 0.9 or clinical evidence of PAD . Clinical evidence of PAD included positive Rose questionnaire, intermittent claudication and peripheral vascular event

Association between PAD and history of cardiac event using odds ratios (OR)

<p><b>Copyright information:</b></p><p>Taken from "Profound influence of different methods for determination of the ankle brachial index on the prevalence estimate of peripheral arterial disease"</p><p>http://www.biomedcentral.com/1471-2458/7/147</p><p>BMC Public Health 2007;7():147-147.</p><p>Published online 6 Jul 2007</p><p>PMCID:PMC1950873.</p><p></p> PAD was defined by an ABI value < 0.9 or clinical evidence of PAD, while history of cardiac event was evident after myocardial infarction or coronary revascularisation. OR, sensitivity and specificity are shown for the different modes of ABI calculation. Sensitivity and specificity are given for the 'detection' or 'exclusion', resp., of a history of cardiac events

ROC curves for the association between ABI values (according to different methods for ABI calculation) and the history of cardiovascular events (myocardial infarction or coronary revascularisation)

<p><b>Copyright information:</b></p><p>Taken from "Profound influence of different methods for determination of the ankle brachial index on the prevalence estimate of peripheral arterial disease"</p><p>http://www.biomedcentral.com/1471-2458/7/147</p><p>BMC Public Health 2007;7():147-147.</p><p>Published online 6 Jul 2007</p><p>PMCID:PMC1950873.</p><p></p> , method #1; , method #2; , method #3; , method #4. The red dashed line represents the line of identity of tpr and fpr