PAD as a risk factor for mortality among patients with elevated ABI--a clinical study.

OBJECTIVE

This study aims to evaluate mortality across ankle-brachial index (ABI) values and to assess the association between elevated ABI, peripheral arterial disease (PAD) and mortality.

DESIGN

This is a retrospective clinical study.

MATERIAL AND METHODS

A total of 2159 patients referred with a suspicion of PAD had their ABI and toe brachial index (TBI) measured by photoplethysmography. ABI > or =1.3 was considered falsely elevated while TBI <0.60 was the diagnostic criterion for PAD among the subjects. The cohort was followed up for total and cardiovascular mortality until 30 June 2008, by record linkage with the National Causes-of-Death Register.

RESULTS

The average follow-up time was 39 months. A total of 576 (26.7%) patients died during the follow-up. Mortality was highest in the elevated ABI group (35.7% for elevated ABI; 30.1% for low ABI and 16.0% for normal ABI, p < 0.001). There was a greater than twofold risk of total, and an increased but statistically non-significant risk of, cardiovascular mortality among patients with elevated ABI. Similar risk ratios were noted for the low ABI (< or =0.9) group. More pronounced associations were observed at both ends of the scale when ABI was divided into sub-categories. The overall survival was significantly worse for the elevated ABI group than for both the normal and the low-ABI group (p < 0.01 and p = 0.013, respectively). PAD was found to be independently associated with both total and cardiovascular mortality among those with elevated ABI (odds ratio (OR): 2.21; 95% confidence interval (CI): 1.01-4.85 and OR: 4.90; 95% CI: 1.50-16.04, respectively).

CONCLUSIONS

The association between elevated ABI and poor survival is similar to that of low ABI. PAD appears to be an independent risk factor for mortality among patients with elevated ABI.