Quantitative and qualitative progression of peripheral arterial disease bynon-invasive testing

There is little information on the progression of peripheral arterial disea se (PAD) over time. A series of 508 patients with a prior examination for P AD were contacted and brought in for follow-up to evaluate the natural hist ory of PAD. A total of 85 patients were excluded because they had intervent ions in both limbs prior to their return visit. Progression was assessed in the remaining 423 patients for a total of 755 limbs, both quantitatively a nd qualitatively using six categories of PAD severity. There was a modest o verall categorical progression of disease: 228 limbs (30.2%) displayed cate gorical progression, while 172 limbs (22.8%) improved over a 4.6-year avera ge follow-up. Through analysis of quantitative change, it was determined th at more quantitative progression occurred than was evident from categorical progression. Two of the three non-invasive tests employed, the ankle/brach ial index (ABI) and posterior tibial peak forward flow velocity (peak PT), showed statistically significant progression during follow-up: mean ABI cha nge = -0.019, 95% confidence interval (CI)= -0.031 to -0.007; mean peak PT change = -2.32 cm/s, 95% CI = -3.20 to -1.44. The toe/brachial index (TBI) also suggested progression: mean change = -0.013, but the 95% CI included n o change. Standard scores (sum of the Z-scores for ABI, peak PT and TBI) we re calculated. The standard score progressed approximately 0.34 units (stan dard deviations), p-value <0.001, over 4.6 years; or about 0.07 standard de viations per year. There were independent and statistically significant (p < 0.05) associations between the rate of PAD progression (standard score ch ange) and age, diabetes, classic ('Rose') intermittent claudication, modera te to severe PAD in the same limb, moderate to severe PAD in the contralate ral limb and future therapeutic intervention. There were independent and su ggestive associations (0.05 < p-value < 0.15) between PAD progression and p ain at rest, mild PAD in the same limb, and mild PAD in the contralateral l imb. PAD progression was not associated with gender, atypical claudication, or amputation status. Thus, in this cohort of PAD patients, PAD on average progressed significant ly over 4.6 years. This progression was independently related to age, diabe tes and several markers of disease severity.