Key messages:
- People who find walking difficult due to pain caused by a lack of blood flow in the legs can be treated with an operation to improve blood flow. Adding an exercise programme to this treatment may help them walk further distances compared to just having an operation, but we are very uncertain due to poor-quality evidence.
- We cannot tell if adding exercise helps improve lower limb blood flow, the distance people can walk without pain, quality of life, need for repeat operations, or death rates.
- The studies involved relatively few participants and had many methodological weaknesses, which means their results may be insufficiently accurate. We need more high-quality evidence to be confident that adding an exercise programme after an operation improves crucial health outcomes for people with peripheral arterial disease.
What is peripheral arterial disease (PAD)?
PAD is a condition where the blood vessels in the legs become narrow or blocked, making it hard for blood to flow. This can cause pain or aching in the legs when individuals walk, and in severe cases, it can lead to problems like pain at rest and wounds that won't heal, which may even lead to amputation (having part of the leg removed).
People with symptoms of PAD are usually treated with medicine and exercise to help prevent it from getting worse. However, this is not enough in some cases and surgery is needed to improve blood flow.
What did we want to find out?
We wanted to see if adding exercise to peoples' routines after surgery for PAD would benefit them more than just having surgery alone. We assessed this by looking at the distance people can walk before needing to stop, the distance they can walk without pain, blood flow in the legs, quality of life, the need for repeat operations, and death rates.
What did we do?
We searched for studies that compared participants who exercised after surgery to improve blood flow in their legs to those who just had surgery alone. Where possible, we combined the results of the studies to see what the effect of treatment was for larger groups of people.
What did we find?
We found 7 studies that involved a total of 376 participants. The studies showed different results. Individually, some studies showed no difference in the distance participants could walk, and some showed an improvement with exercise.
For most of our outcomes of interest, we were able to combine the results from only two studies. For death and repeat operation rates, we were able to combine the results of 6 and 5 studies, respectively.
When combined, the evidence showed that the addition of exercise treatment may increase people's maximum walking distance, but we are very uncertain. We are also very uncertain whether additional supervised exercise following surgery compared with surgery alone has an effect on the distance people could walk without any pain or the total distance that they could walk within 6 minutes. We are also very uncertain whether additional supervised exercise has an effect on lower limb blood flow, quality of life, the need for repeat operations, or death.
Overall, we can't be sure if adding exercise treatment after surgery for PAD is helpful for people, and more studies are needed to answer this question. However, none of the studies indicated that supervised exercise training harms patients following surgery for PAD. Thus, adding exercise training after surgery seems to be safe.
What are the limitations of the evidence?
There were many limitations of the evidence we reviewed. The studies we included had problems with how they were designed and carried out, which may mean the results are inaccurate. For instance, some studies put a time limit cap on participants' exercise training, making it challenging to understand the true impact of adding exercise after surgery and its effects on the primary outcomes.
Not all studies made their data available in a useful way, which can be a significant problem for researchers trying to understand the findings. This made it difficult to assess the quality of the studies fully. There were also relatively small numbers of people included in the available studies.
All these factors limited our ability to combine the studies to get a clearer picture of the overall effect which they measured.
How up to date is this evidence?
The evidence is current to 14 March 2023.
There is very uncertain evidence that additional exercise therapy after successful lower limb revascularisation may improve absolute maximal walking distance at the end of follow-up compared to standard care. Evidence is also very uncertain about the effects of exercise on pain-free walking distance, six-minute walk test distance, quality of life, ankle-brachial index, mortality, and reintervention rates. Although it is not possible to confirm the effectiveness of supervised exercise compared to standard care for all outcomes, studies did not report any harm to participants from this intervention after lower limb revascularisation.
Overall, the evidence incorporated into this review was very uncertain, and additional evidence is needed from large, well-designed, randomised controlled studies to more conclusively demonstrate the role additional exercise therapy has after lower limb revascularisation in people with PAD.
Peripheral arterial disease (PAD) is characterised by obstruction or narrowing of the large arteries of the lower limbs, usually caused by atheromatous plaques. Most people with PAD who experience intermittent leg pain (intermittent claudication) are typically treated with secondary prevention strategies, including medical management and exercise therapy. Lower limb revascularisation may be suitable for people with significant disability and those who do not show satisfactory improvement after conservative treatment. Some studies have suggested that lower limb revascularisation for PAD may not confer significantly more benefits than supervised exercise alone for improved physical function and quality of life. It is proposed that supervised exercise therapy as adjunctive treatment after successful lower limb revascularisation may confer additional benefits, surpassing the effects conferred by either treatment alone.
To assess the effects of a supervised exercise programme versus standard care following successful lower limb revascularisation in people with PAD.
We searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, two other databases, and two trial registers, most recently on 14 March 2023.
We included randomised controlled trials which compared supervised exercise training following lower limb revascularisation with standard care following lower limb revascularisation in adults (18 years and older) with PAD.
We used standard Cochrane methods. Our primary outcomes were maximum walking distance or time (MWD/T) on the treadmill, six-minute walk test (6MWT) total distance, and pain-free walking distance or time (PFWD/T) on the treadmill. Our secondary outcomes were changes in the ankle-brachial index, all-cause mortality, changes in health-related quality-of-life scores, reintervention rates, and changes in subjective measures of physical function. We analysed continuous data by determining the mean difference (MD) and 95% confidence interval (CI), and dichotomous data by determining the odds ratio (OR) with corresponding 95% CI. We used GRADE to assess the certainty of evidence for each outcome.
We identified seven studies involving 376 participants. All studies involved participants who received either additional supervised exercise or standard care after lower limb revascularisation. The studies' exercise programmes varied, and included supervised treadmill walking, combined exercise, and circuit training. The duration of exercise therapy ranged from six weeks to six months; follow-up time ranged from six weeks to five years. Standard care also varied between studies, including no treatment or advice to stop smoking, lifestyle modifications, or best medical treatment. We classified all studies as having some risk of bias concerns. The certainty of the evidence was very low due to the risk of bias, inconsistency, and imprecision. The meta-analysis included only a subset of studies due to concerns regarding data reporting, heterogeneity, and bias in most published research.
The evidence was of very low certainty for all the review outcomes. Meta-analysis comparing changes in maximum walking distance from baseline to end of follow-up showed no improvement (MD 159.47 m, 95% CI -36.43 to 355.38; I2 = 0 %; 2 studies, 89 participants). In contrast, exercise may improve the absolute maximum walking distance at the end of follow-up compared to standard care (MD 301.89 m, 95% CI 138.13 to 465.65; I2 = 0 %; 2 studies, 108 participants). Moreover, we are very uncertain if there are differences in the changes in the six-minute walk test total distance from baseline to treatment end between exercise and standard care (MD 32.6 m, 95% CI -17.7 to 82.3; 1 study, 49 participants), and in the absolute values at the end of follow-up (MD 55.6 m, 95% CI -2.6 to 113.8; 1 study, 49 participants). Regarding pain-free walking distance, we are also very uncertain if there are differences in the mean changes in PFWD from baseline to treatment end between exercise and standard care (MD 167.41 m, 95% CI -11 to 345.83; I2 = 0%; 2 studies, 87 participants).
We are very uncertain if there are differences in the absolute values of ankle-brachial index at the end of follow-up between the intervention and standard care (MD 0.01, 95% CI -0.11 to 0.12; I2 = 62%; 2 studies, 110 participants), in mortality rates at the end of follow-up (OR 0.92, 95% CI 0.42 to 2.00; I2 = 0%; 6 studies, 346 participants), health-related quality of life at the end of follow-up for the physical (MD 0.73, 95% CI -5.87 to 7.33; I2 = 64%; 2 studies, 105 participants) and mental component (MD 1.04, 95% CI -6.88 to 8.95; I2 = 70%; 2 studies, 105 participants) of the 36-item Short Form Health Survey. Finally, there may be little to no difference in reintervention rates at the end of follow-up between the intervention and standard care (OR 0.91, 95% CI 0.23 to 3.65; I2 = 65%; 5 studies, 252 participants).