Ankle-brachial index and mortality in a cohort of questionnaire recorded leg pain on walking.

Abstract

To study the association between the ankle-brachial pressure index (ABPI), premature death and the need for surgical treatment for lower limb ischaemia. Population based cohort study. Three hundred and fifty-three men and women, 50-89 years old, underwent a leg pain questionnaire and measurement of ABPI and was then followed for 10 years. All cause mortality, vascular procedures and major amputations. A low ABPI was independently associated with premature all cause mortality in the multiple regression analysis, carrying a relative risk of 3.4 (95% confidence interval 2.0-5.9) and 2.1 (1.3-3.3) for ABPIs <or=0.50 and 0.51-0.80, respectively, compared to those with ABPI >or=1.0. Individuals with an ABPI in the interval 0.81-0.99 suffered only a slight, not statistically significant risk increase compared to normals. A low ABPI at baseline implied a continuous constant increased risk of death throughout the study period. The same risk was observed among elderly (70-89, median 77 years), and in the middle aged (50-69, median 63 years) individuals. The vast majority of those subjected to vascular intervention or major amputation during follow-up had an ABPI<or=0.8 at baseline (83 and 89%, respectively). However, within that group, the individual ABPI was not predictive for surgical intervention. The association found between an ABPI <or=0.8 and premature mortality in this cohort of symptomatic subjects implies that the ABPI is a powerful, independent predictor for premature death. The prognostic information carried by an ABPI in the interval 0.81-0.99 remains uncertain. Septuagenarians and octogenarians carry the same risk increase associated with a low ABPI as those in the middle ages.