Some 50% to 80% of patients with peripheral arterial disease (PAD) are symptomatic with intermittent claudication (IC).1 IC is defined as muscle discomfort in the lower limb(s) elicited by exercise that resolves after a short period of rest.1 IC is associated with significant disability, reduced quality of life,2,3 and an increased risk of death.4 A recent study found a significant difference in survival when patients with and without PAD were compared; for instance, the all-cause and cardiovascular mortality rates were 24% and 7.7% in patients with PAD vs 9.5% and 2.4% in patients without PAD, respectively.5 The unfavourable prognosis associated with PAD is dominated by the concomitant presence of cerebral and coronary artery disease (CAD) due to generally accepted risk factors (smoking, hypertension, diabetes mellitus, hyperlipidaemia).6-8 The estimated overall prevalence of atherosclerotic CAD in PAD is 72%, with an obstructive nature in 61% to 98% in certain subgroups.9,10 The Quebec Cardiovascular Study reported that the risk of fatal and nonfatal cardiovascular events in men with IC was twice as high compared with men without known cardiovascular disease.11International guidelines state that treatment of IC should consist of a multimodal approach that includes cardiovascular risk reduction combined with symptomatic treatment.1,7 First-choice symptomatic treatment, demonstrated by Level I evidence, is daily-supervised exercise therapy (SET).12-17 Apart from symptomatic improvement, a 12-week SET program also reduced overall cardiovascular mortality by 52% and morbidity by 30%.18 Although it is generally accepted that SET should be part of the initial treatment for each patient with IC, this therapeutic tool is seriously underused in clinical practice.19-21 A study among surgeons in the United Kingdom revealed that only 24% of IC patients had access to SET.21 Moreover, a large variation was found in the proportion of eligible patients referred to such an exercise program. Lack of knowledge on referral criteria was also observed in a recent nationwide survey among Dutch vascular surgeons. Approximately 70% of the interviewed surgeons were convinced that coexisting cardiopulmonary comorbidity or aortoiliac stenosis or occlusion, or both, were relative contraindications for participation in a SET program.20 These doubts are strengthened by a worry among physical therapists providing SET because they fear the onset of cardiovascular events that may possibly occur during exercise. Moreover, physical therapy guide- lines advocate cardiac screening before SET,22 although evidence to support such a strategy is currently lacking. SET is often described as well tolerated, and two studies re- ported cardiovascular complications were rare.23,24 The aim of the present study was to analyze the safety of SET in patients with IC in terms of onset of untoward (cardio- vascular) events.
Fig. Flow chart of study selection. *Defined as1 missing data on complications during supervised exercise training (SET),2 incomplete data on reasons for dropout, or3 nonresponse on e-mail request as a final attempt to obtain information.