Estimation of walking distance in intermittent claudication: need for standardization.

Intermittent claudication is the most striking symptom of peripheral arterial occlusive disease, a disease mostly confined to the lower limb arteries and characterized by ischaemic processes in one or both legs and important reductions of the patients’ walking distance. In a large number of patients significant reduction of symptoms can be achieved by correction of associated risk factors, particularly smoking, and by (supervised) training programmes (walking). The treadmill is generally accepted as the reference method for evaluating severity of intermittent claudication and effects of treatment options. However, as yet there are no sound literature data to sustain these widely accepted indications. Ideally any standardization of a treadmill test should fulfil several criteria: simplicity and cheapness, no complications, a good reproducibility and predictive value and accuracy against a gold standard. Whether arteriography of the lower limb arteries constitutes the gold standard to assess severeness of arterial lesions remains a matter of debate. A recent review of all methodology used in the literature to measure claudication distance revealed that at present it is measured spuriously and inappropriately, is inaccurately reported and usually misinterpreted. We will limit ourselves to critical discussion of the evaluation of the walking distance by treadmill tests or alternatives. The following parameters can be derived from a treadmill test: (1) the claudication-free walking time or distance; (2) the maximal walking time or distance. We prefer to use the distance parameters, because this is more meaningful than considering walking time. The claudication-free distance is the distance that a claudicant can walk on the treadmill without pain in the limb(s). The pain-free walking or the initial claudication distance is another method of measuring the claudication-free walking distance. The maximal walking distance is the maximal distance that a claudicant can walk on a treadmill. Other terms for