Despite the documented benefits of supervised exercise in patients with claudication, its effect on actual clinical practice has been disappointing due to a lack of reimbursement. But practitioners and researchers have been investigating other options, with encouraging preliminary results.
By Cary Groner
Clinicians treating intermittent claudication, a common symptom of peripheral arterial disease (PAD), face a vexing conundrum: the safest and most effective treatment, supervised walking, isn’t reimbursed by Medicare or private insurance. The result has been a scramble to find ways to give patients relief without draining their bank accounts.
Claudication refers to leg pain while walking; the pain is often felt in the calves, but may also occur in the thighs or buttocks.1 According to Mary McDermott, MD, a professor of medicine and preventive medicine at Northwestern University’s Feinberg School of Medicine in Chicago, by definition the pain begins as a result of exertion and typically subsides within 10 minutes of stopping to rest. The reasons for the condition are complex and systemic.
“Blockage in the vessels contributes, but there also seems to be a muscle problem that develops in patients with PAD that involves the mitochondria and that may not be reversible,” McDermott said. “These patients tend to have fewer muscle fibers in the legs, and they also have systemic atherosclerosis. Cardiovascular and endothelial functions are impaired. But when it comes to walking, claudication is mainly related to blood flow and muscle impairment.”
Arterial lesions limit the flow of blood, starving muscles of the oxygen they need during exertion, and this causes pain.1 According to McDermott, common areas of occlusion include the femoral arteries and the aortal iliac. One issue from both a research and clinical perspective, she said, is that claudication occupies a somewhat blurry position on a spectrum of afflictions related to PAD.
“Most people with PAD do not have classic symptoms of claudication,” she explained. “But they still have leg pain, and they can still improve with exercise. Some patients tell you they’re asymptomatic, but when you have them do a six-minute walk, they get symptoms. The problem is that they’ve self-restricted their activities to avoid those symptoms.”
McDermott has conducted studies on exercise and PAD together with claudication and its close relatives. For example, in a 2009 paper in the Journal of the American Medical Association, she assessed whether supervised treadmill exercise and lower extremity resistance training, respectively, improved functional performance, versus a control group that participated in nutritional information sessions, in patients with and without intermittent claudication (IC).2 Of 156 participants, about 19% had strictly defined claudication. Nevertheless, supervised treadmill exercise improved six-minute walk distance, walking performance, quality of life (QOL), and other measures, in PAD patients both with and without classic symptoms of IC. Resistance training had similar effects.
“We’re not the only people to describe this,” McDermott said. “Most people with PAD have leg pain—just not classic claudication. It’s similar to the relationship between coronary artery disease and angina.”
Research delineates the benefits of supervised exercise for IC patients. For example, a 2008 Cochrane review of 22 clinical trials found that exercise significantly improved maximum walking time, ability, and distances, and that benefits continued up to two years after the intervention.3
“Supervised exercise occupies a central role in PAD,” said William Hiatt, MD, a professor of medicine in the Division of Cardiology at the University of Colorado (UC) School of Medicine in Denver. “The key components are a workload on the treadmill that is sufficiently high to induce claudication pain, then allowing the patient to experience moderate claudication, then resting, then getting back on the treadmill. You repeat that over the course of an hour.”
Judy Regensteiner, PhD, another UC Denver professor of medicine and a colleague of Hiatt’s, agreed.
“Supervised exercise is a very effective therapy for claudication,” she said. “It improves both walking ability and quality of life.”
Despite the advantages supervised exercise offers, its effect on actual clinical practice has been disappointing due to the lack of reimbursement. Physicians are presented with difficult choices as a result.
“Current behavior in vascular medicine is that when patients are diagnosed with claudication, or with PAD in general, they are often referred to the cath lab straightaway,” Hiatt said. “There are reasons for that: patients want instant gratification and people who do the procedures get paid. Patients may be sent to an exercise program only if they are not good catheterization candidates.”
Another result of problematic incentives has been a push toward unsupervised, community-based exercise. Until recently, such programs haven’t appeared particularly promising. For example, a 2013 update to a 2006 Cochrane review compared 14 studies with 1002 participants and found that only supervised exercise had a significant benefit on treadmill walking distance, versus nonsupervised regimens, at three and six months.4
Conversely, however, some studies suggest that unsupervised exercise can have positive effects. Hiatt, Regensteiner, and two colleagues authored a 2013 literature review of 10 randomized controlled trials and reported that, though supervised programs were more effective than community walking, more recent studies that included better advice and feedback resulted in outcomes similar to those in the supervised exercise trials.5 In other words, efficacy may depend to some extent on how you define “unsupervised.”
“I think that, if you have a well-designed program and lots of interaction with the subjects, you can make home exercise work,” Hiatt said. “It may not be quite as good, but it’s certainly more cost-effective than in-hospital management.”
“You have to check in with people,” Regensteiner agreed. “Teaching them to exercise and monitoring them is very helpful, and if you can do those things I think it will be an effective therapy.”
A recent paper by Mary McDermott supports this notion.6 In a trial of 194 patients with PAD (with and without classic claudication), participants were randomized to either a home-based group-mediated walking intervention or to a control group that received group-based health education. Those in the intervention cohort met once weekly for 90 minutes with other participants in groups led by a trained facilitator. They spent 45 minutes in discussion and 45 minutes walking around an indoor track; the discussions included topics such as the benefits of walking for PAD, goal-setting, self-monitoring (in this case, using pedometers), and managing pain. They were also instructed to do over-ground walking at least five days per week, working up to 50 minutes per session; they walked to severe leg discomfort, then rested until the pain subsided enough to resume.
Over the course of the study, those in the walking cohort significantly increased their six-minute walk distance, maximal treadmill walking time, and other scores, whereas controls did not.
“These patients have so few therapeutic options open to them, and exercise works,” McDermott said. “But there are people in my practice that can’t afford to come down to the center for supervised exercise three times a week. We need to come up with interventions they can do at home, that they’ll adhere to.”
Another recent study bolsters the case for home-based exercise. In a controlled trial published in Circulation in 2011, researchers at the Oklahoma University Health Sciences Center in Oklahoma City randomized 119 patients to three groups: 29 for home-based exercise, 33 for supervised exercise, and 30 as usual-care controls.7 Home-based exercise was quantified with a step activity monitor and designed to be as similar to the supervised program as possible. Both consisted of 12 weeks of intermittent walking to near-maximal claudication pain three days a week, progressing to 45 minutes per session by the last two weeks of the study. Both the supervised and unsupervised groups significantly increased claudication onset time and peak walking time; surprisingly, only the home-based intervention also increased average cadence.
Andrew Gardner, PhD, the study’s lead author and an exercise physiologist at the university, said that though supervised walking remains the gold standard, home-based alternatives show increasing promise.
“The literature is full of studies showing that unsupervised exercise doesn’t work, but it’s misleading because most of them consisted of little more than the patients receiving advice about exercise,” Gardner said. “In our program we monitored them intensely with a computerized pedometer, and it worked reasonably well.”
Because diabetes is a risk factor for PAD (55% of PAD patients also have diabetes),8 one study has examined the effect of a home-based walking intervention in patients with both conditions.9 Researchers randomized 145 participants to either a program targeting levels of readiness to engage in routine walking for exercise, or to a control group that received twice-monthly status checks by phone. After six months, neither group differed significantly from baseline levels with regard to maximal treadmill walking distance; however, the home-based intervention did improve walking speed and QOL.
The study’s lead author, Tracie Collins, MD, MPH, told LER that the study included both those with classic claudication and those with related symptoms such as pain that began before heavy exertion.
“The first component of our intervention was that our research team had a face-to-face counseling session with patients right after they were randomized,” Collins said. “We went over risk factor management such as diabetes, blood pressure, and lipid control, as well as smoking cessation. We encouraged them to walk, and scheduled them for a home-based walking training session, which covered details such as the kind of shoes to wear, walking until they had moderate discomfort, and so forth.”
Patients were asked to walk three days a week on their own, then to join one of the researchers—an exercise instructor—one day a week to walk with others in the cohort, for social support. They also received phone calls every two weeks to assess their status.
Collins shares Mary McDermott’s concern about patients with different symptom subtypes.
“Some are asymptomatic, some have atypical leg symptoms, and some have classic claudication,” she said. “We’ve done a good job targeting those with claudication, and we are beginning to learn more about those with atypical symptoms, but more needs to be done to understand those who are asymptomatic. This is a large group of patients who are electing to be less active to avoid discomfort. They would benefit from exercise therapy, but they are missed, and physicians aren’t telling them to walk the right way.”
The right way, in this case, means what Collins refers to as a training effect, which helps patients’ muscles become more conditioned.
“That comes about from pushing through moderate or severe pain, then stopping and letting the muscle recover, then getting up and doing it again,” she said. “We need a training effect in home-based programs that mimics what you get from supervised walking therapy.”
Researchers and clinicians have developed alternative approaches to exercise for claudication patients who, for various reasons, may not respond well to walking.
For example, in a 2009 study, researchers at the University of Minnesota in Minneapolis randomized 41 patients to 12 weeks of supervised exercise training using either treadmill walking, dynamic arm exercise, or a combination of the two.10 They discovered that maximal walking distance increased almost as much in the arm exercise group (53%) as in the treadmill and combination groups (69% and 68%, respectively).
In a 2011 systematic review of 36 trials, Australian researchers reported that several exercise modes—including aerobics, walking, resistance training, and weight lifting—significantly improved walking capability in claudication patients.11 And a 2013 paper by the same lead author reported that high-intensity progressive resistance training improved performance on the six-minute walk test in 22 older patients with claudication.12
The lead author of both studies, Belinda Parmenter, PhD, is an exercise physiologist at the University of Sydney in Australia. She told LER that she first became interested in alternative training methods for claudication patients by working with her father, a vascular surgeon.
“He had patients who couldn’t just go home and walk due to their comorbidities,” she said. “They had knee osteoarthritis, or chronic low back pain, or they’d had a stroke or an amputation, and they couldn’t cope with the level of pain they were being asked to walk to. Most weren’t candidates for surgery, due to the cardiovascular risk. So my father was trying to figure out how to help them.”
Parmenter was working on her doctorate at the time; her advisor had had good results with weight and resistance training for patients with a variety of conditions, and suggested she investigate these methods for PAD and claudication patients. Parmenter developed a circuit of what she calls lower extremity aerobic exercises that included squats, jumps, calf raises, knee extensions, and the like.
“People were strengthening the leg muscles, but they were also elevating their heart rates and improving their aerobic fitness,” she said. “It involved a lot of different muscles as opposed to just those related to gait, so the claudication pain didn’t come on as much. If you can find a mode of exercise for these people so that they improve not only their walking, but also their aerobic fitness, you are addressing the bigger picture of overall cardiovascular risk, the whole spectrum of the disease.”
In her review article, Parmenter also reported that, as in the Minnesota study, arm exercise (in this case, cranking) was effective. In all cases, supervision while the routines were being established was critical.
“Supervision is really important to ensure that there is correct technique and that they are training at the right intensity,” she said. “But once you educate the patient about those things, there is definitely room to move them into an unsupervised environment.”
One exercise notably absent from the literature is swimming. Parmenter suspects this has to do with the underlying cardiovascular issues associated with claudication and PAD.
“When you enter an aquatic environment, you increase the pressure placed on the heart,” she said. “Water immersion increases central venous pressure, venous return, stroke volume, and cardiac output, which all increase left ventricular wall stress and can increase ST depression and angina. Cold water can also decrease heart rate and increase ventricular irritability and arrhythmias; and patient monitoring and emergency precautions are more difficult when patients are in the water.”
As noted earlier, many clinicians turn to vascular interventions to treat claudication. These may include approaches such as angioplasty in the leg arteries or stent placement in the pelvic arteries.
“People with claudication typically experience leg pain not due to blockage in the leg arteries, but rather in the pelvis,” said Timothy Murphy, MD, a professor of diagnostic imaging at Brown University Medical school and an interventional radiologist at Rhode Island Hospital, both in Providence.
“The leg arterial obstructions are more common, but someone with an iliac (pelvic) obstruction is more likely to undergo an intervention because it’s technically more feasible and it’s known to provide more durable results.”13
The clinicians who spoke with LER generally agreed that angioplasty should not be considered a substitute for exercise, but historically it has often been used as such due to the insurance environment. Studies suggest that, though revascularization provides quicker relief than exercise, the long-term results are about the same. For example, in a 2013 study comparing supervised exercise with revascularization, the approaches were equally effective in improving functional performance and QOL, but, because of the invasive aspects of revascularization, the authors suggested exercise should be the first-line treatment.14 A similar study from 1996 reported that exercise conferred greater improvements in maximum walking distance than angioplasty.15 And in 2009, researchers reported that, in 151 claudication patients randomly assigned to receive either endovascular revascularization or supervised exercise, the revascularization group improved more quickly, but the advantage was lost at six and 12 months, at which point both groups were equivalent in functional capacity and QOL scores.16
Increasingly, however, clinicians are interested not in opposing the approaches but in combining them.
“Angioplasty plus exercise is better than either individual therapy,” said Mary McDermott. “People who get angioplasty have immediate relief of symptoms, but it is not sustained. The more time that has passed since your procedure, the more common is restenosis. With the exercise, you don’t get immediate relief, but if you stick with it, at four to six weeks you’ll start seeing benefit.”
Andrew Gardner agreed.
“If you really want to improve blood flow through the major arteries of the leg, revascularization is the way to do it, because exercise isn’t going to diminish the arterial plaque,” he said. “Unfortunately, that doesn’t necessarily mean you’re going to walk better, because there are still issues with the smaller vessels downstream, and the muscles are weak, and surgery doesn’t treat that. That’s where exercise comes in; it improves muscle function, and the theory is that you’re building more capillaries and rerouting the blood flow away from the blockage, so the muscles get the blood they need.”
Research supports combining the approaches. For example, a 2013 article reported that in 50 claudication patients randomized to receive angioplasty alone or angioplasty followed by exercise, the latter group had significantly better QOL and walking distance scores at 12 months.17 Other papers have noted similar findings.18,19
A 2012 paper in Circulation reported the results of the CLEVER (Claudication: Exercise versus endoluminal revascularization) study, in which 111 patients with PAD were randomized to receive one of three treatments: optimal medical care (OMC), OMC plus supervised exercise (SE), or OMC plus stent revascularization (ST).20 Researchers found that SE resulted in better treadmill walking performance than ST, even for those with aortoiliac PAD, but that ST was associated with better patient-reported QOL.
Timothy Murphy, the study’s lead author, told LER that he considers the matter open.
“I think whether stenting adds anything to supervised exercise is still unanswered,” Murphy said. “However, it wouldn’t surprise me if the combination is ideal, because patients are usually deconditioned before you revascularize them. If you put in a stent, you’re going to get a much faster rise in their peak walking times, and that lets you focus on cardiorespiratory fitness since they’re less limited by leg pain.”
“If there are revascularization options, that’s fine, and patients should get them,” added Will Hiatt. “But they should also get an exercise program, and the combination is one of the best approaches.”
Hiatt noted that these are, nevertheless, essentially symptom treatments, and that patients will continue to have to address the basic issues.
“What deals with the underlying problem is risk factor management, use of antiplatelet drugs, smoking cessation, lipid and blood pressure control,” he said. “Exercise controls some of that, but it doesn’t directly modify the disease process.”
Cary Groner is a freelance writer based in the San Francisco Bay Area.
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