OBJECTIVES: To investigate, in patients with peripheral arterial disease (PAD), the association between the level of the Ankle-Brachial Pressure Index (ABPI) at time of diagnosis and clinical outcome. METHODS: The data set of the Limburg PAOD Longitudinal Study (n=3649, mean follow-up time 7.2 years) was analyzed for this purpose. The ABPI was measured by trained personnel using handheld Doppler devices. Subjects were classified into 6 baseline ABPI categories ranging from ABPI > or = 1.10 ('certainly normal') to ABPI<0.50 ('seriously reduced'). Outcome measures were progressive limb ischaemia, cardiovascular morbidity and cardiovascular mortality. Cox proportional hazard models were used to investigate the associations (including hazard ratio's, HR) between different ABPI categories and outcome events. RESULTS: As compared to persons with an ABPI > or = 1.10 ('certainly normal'), patients with a baseline ABPI <1.00 (categories 'probably normal' and worse) were at high risk to develop progressive limb ischaemia (HR 3.3 - 9.0). Additionally, patients with a baseline ABPI <0.90 (categories 'moderately reduced' and worse) were at higher risk to experience a non-fatal cardiovascular disease (HR 1.5 - 1.7). Moreover, patients with a baseline ABPI <0.70 ('clearly' and 'seriously' reduced ABPI) were at high risk to die from a cardiovascular or other cause (HR 2.3). CONCLUSION: The ABPI can be helpful in identifying subjects at high risk for a poor cardiovascular outcome, in whom strict cardiovascular risk management would be appropriate. AD - Departments of General Practice and Biological Health Sciences, Universiteit Maastricht, Care and Public Health Research Institute, The Netherlands.