[Comparison of two coronary risk equivalents: diabetes mellitus and peripheral arterial disease].

BACKGROUND AND OBJECTIVE

Diabetes mellitus (DM) and peripheral arterial disease (PAD) are both coronary artery disease equivalents ("coronary equivalents"). It was the aim of this study to ascertain (1) to what extent each of these diseases differs from the other in respect of early death, (2) how frequently DM and PAD occur together in elderly patients seen in general practice and (3) what risk patients with DM and concomitant PAD carry.

PATIENTS AND METHODS

In the prospective non-interventional study--"German Epidemiological Trial on Ankle Brachial Index"--6,880 unselected patients, aged 65 years or more, from 344 general medical practices were followed over five years and the incidence of deaths and of cardiovascular events recorded. DM was defined according to the medical diagnosis and/or if the HbA1c was > or = 6.5% and the ankle brachial index (ABI), determined by Doppler sonography. PAD was defined as an ABI of < 0.9 or the presence of intermittent claudication or state after peripheral revascularization/amputation. Survival rates were obtained using Kaplan-Meier estimate curves and Cox's proportional hazard model. 59 patients with an ABI > 1.5 were excluded from the study. Hazard ratios (HR with 95% confidence intervals [CI]) were adjusted according to known risk factors.

RESULTS

The overall observation period for all the patients amounted to nearly 33000 patient-years (PY). The risk of death of patients with DM but no PAD (n = 1,220; 17.9%) was 1.5 times the risk of death (HR, 95% CI 1.2-1.8) of persons with neither disease (n = 4 172; 61.2%) and the risk of those with PAD but no DM (n = 918, 13;5%) was 1.7 times of those persons without either disease (HR, 95% CI 1.4-2.0). The risk for persons with DM and PAD (n = 511; 7.5%) was nearly 3 times that of persons without either disease, after adjustment for other cardiovascular risk factors (HR 2.8, 95% CI 2.3-3.4). The lower the ABI in persons with or without DM the greater the number of deaths per 1000 PY.

CONCLUSIONS

These results confirm that diabetics and patients with PAD have a clearly increased risk of early death. These patients need intensive treatment of the risk factors. This is especially true for patients who have DM and PAD concomitantly.