Development and Validation of a Clinical Prediction Rule for Lower Limb Critical Limb Ischaemia (PREDICCMI)

Overview

Critical limb ischaemia (CLI) is the most serious stage of peripheral occlusive arterial disease (POAD). Despite progress in the revascularization procedures, half these patients experience amputation or death after one year. One issue is to identify these subjects because aggressive treatment is necessary in those cases, while in others (ie leg ulcer in a patient with POAD but no rest lower limb ischaemia), revascularization will not be necessary. Then it would be useful to develop a simple score to help the physician to improve diagnosis of CLI.

Today many patients with suspected critical limb ischaemia do not have objective assessment of limb ischaemia despite recommendations, mainly because of lack of vascular medicine units able to measure ischaemia with adequate methods such as toe pressure or TCpo2. It would be very useful to better identify the patients who need to be explored, or at least to have an evidence-based clinical assessment in those who cannot be explored . The objective is to develop a simple clinical prediction rule of critical lower limb ischaemia. Two definitions are currently used for critical limb ischaemia. In both definitions, objective confirmation is needed for critical limb ischaemia by measurement of ankle pressure, toe pressure or transcutaneous oxygen pressure. These two latter measurements are mandatory in the numerous patients whose ankle pressure measurement is not possible (diabetes, chronic renal failure). Unfortunately few vascular medicine units exist to carry out these measurements, so that it would be useful to better identify those patients who need to be explored. In those who cannot be explored, better clinical assessment would also be very useful. The investigators aim to develop a simple clinical prediction rule by completing a specific clinical chart in the patients hospitalized for peripheral occlusive arterial disease in Bordeaux, Toulouse and Limoges university hospital vascular medicine units and included in the COPART II cohort. Internal validation will be performed using cross-validation and bootstrap methods. To achieve the secondary objective, the patients will be followed-up for the duration of the study (ie from 1 to 3 years) to evaluate the prediction of clinical outcomes (death or amputation) by both definitions of critical limb ischaemia.