Pain Management and Patient Education for Physical Activity in Intermittent Claudication (PrEPAID)

Peripheral Arterial disease (PAD) affects 2.7 million people in the United Kingdom (UK). The most common symptom that patients experience is Intermittent Claudication (IC), which is pain in the buttock, calf or thigh precipitated by exercise and relieved by rest. The underlying cause of PAD is atherosclerosis, which leads to arterial stenosis, inadequate blood flow and build-up of lactic acid during exercise. Patients with IC have impaired quality of life due to reduced physical capacity. Furthermore, due to the diffuse nature of atherosclerosis and the involvement of other arterial beds, they have 3-4 times increased mortality compared to age and sex matched controls.

Patients with symptomatic PAD should receive the same secondary prevention management as patients with symptomatic coronary artery disease. Improving daily physical activity (PA) is particularly important in individuals with IC as lower PA levels have been recognised as a strong predictor of increased morbidity and mortality in this population. Current National Institute for Health and Care Excellence (NICE) guidelines recommend the use of supervised exercise programmes (SEPs), encouraging patients "to exercise to the point of maximal pain", as first line treatment. SEPs has been shown to be cost-effective when compared to other treatment options such as endovascular intervention and surgical revascularisation. However, while systematic reviews show that SEPs lead to a significant improvement in the absolute walking distances of patients with IC on a treadmill, it is unclear if this is sustained or leads to improvement in daily PA. Furthermore, due to the considerable extra resources required to deliver the recommended 3 months exercise programme (30-45 minutes 3x weekly), SEPs are not always routinely available to National Health Service (NHS) patients, and time and travel costs tend to lead to low patient uptake and high attrition rates. Therefore, investigating the feasibility of using low-cost, patient-centred interventions that can support increased PA is warranted.

Lack of self-efficacy, attributed to poor understanding of the disease and uncertainty regarding the importance of exercise, has been shown to be a major barrier to exercise uptake in this population. Educating patients with IC about their disease pathology and the benefits of walking is key to enhancing success of secondary prevention strategies for people with IC. Investigators recently piloted a structured, patient-centred education intervention (SEDRIC) with the specific aim of educating patients with IC about their condition, improving patient ownership, and promoting self-managed walking. In addition to improved treadmill walking distances, investigators found out that there was a trend for patients to increase their daily PA.

For patients with IC to gain benefits of secondary prevention, exercising beyond the point when pain occurs is recommended, representing another barrier to engagement in PA. Despite this, investigators' systematic review found that pain management as a route to facilitate exercise and PA has rarely been explored. Recent interest has focused on the use of TENS (a low-cost, non-invasive pain management device) to improve angiogenesis, muscle function, pain and walking distances in patients with IC. TENS has a strong placebo effect in pain conditions, and testing effectiveness against placebo is advocated. In a proof-of-concept pilot study, Investigators demonstrated that TENS could significantly improve pain and increase treadmill walking distances above placebo levels. Our exploratory study also established that home use of TENS was both acceptable and provided self-reported improvement in PA in individuals with IC.

Although patient-centred education (SEDRIC) and TENS have both demonstrated potential to improve daily PA in people with IC, the use of these components in combination has not previously been evaluated. Investigators therefore propose a 2 x 2 (TENS versus placebo TENS x SEDRIC versus no additional education) feasibility Randomised Controlled Trial (RCT) that will compare use of TENS against placebo TENS with and without a patient-centred education programme.

Investigators have conducted a series of pilot studies underpinning both aspects of the intervention. Investigators have demonstrated in an experimental lower limb ischaemic pain model in healthy volunteers (n=28) that TENS significantly reduced onset of pain (by 29 seconds; 23%), tolerance of pain (by 203 seconds; 53%) and the pain endurance (by 173 seconds; 67%), compared to placebo TENS. Following this, in a proof-of-concept pilot study, investigators demonstrated that TENS when applied to patient with IC exercising on a treadmill (n=40) significantly improved absolute claudication distance (ACD) above placebo levels (approx. mean individual increase in ACD of 40%, p=.025, r= .53). Our phase 2 study also established that home use of TENS was both acceptable and provided self-reported improvement in PA in individuals with IC. Investigators have not assessed the ability of TENS to improve ACD when used during daily life.

Similarly, this research group developed and piloted SEDRIC, a structured, patient-centred education intervention with the specific aim of educating patients about their condition, improving patient ownership, and promoting self-managed walking. Investigators found that in patients with PAD (n=14), treadmill walking distances (30%) and quality of life (32%) improved from baseline after 6 weeks of structured education, and there was a trend for patients to increase their daily PA (approx. 8% change from baseline).

The aim is to determine the feasibility of electrical stimulation via a low-cost CE-marked device used within a patient centred education programme to improve walking distances in patients with PAD.

The following research questions will be answered by this project:

• What is the feasibility (i.e. recruitment and retention rates, adherence, safety, sample size for a definitive trial, potential for effectiveness) of conducting a definitive RCT comparing TENS with and without patient-centred education?
• How acceptable are TENS and patient-centred education as interventions on their own or in combination in patients with IC?

Inclusion criteria

• Clinical diagnosis of symptomatic Peripheral Arterial Disease (PAD) including resting Ankle Brachial Pressure Index (ABPI) <0.9 in at least one leg
• Stable IC for ≥3 months
• Walking limited primarily by claudication
• Able to exercise on a treadmill
• Able to read and speak English to a level allowing satisfactory completion of the study procedures
• Able to provide written informed consent for participation

Exclusion criteria

• Planned surgical or endovascular intervention for PAD within the next 3 months
• Critical limb ischaemia
• The presence of any absolute contraindications to exercise testing/training as defined by the American College of Sports Medicine (ACSM)
• Previous experience of using TENS/ structured patient education for PAD
• Contraindications to TENS (including epilepsy, dermatological conditions, indwelling electrical pumps/pacemakers) and inability to apply TENS independently.
• Patients who require walking aids including artificial limbs
• Major surgery, myocardial infarction or stroke/ Transient Ischaemic Attack (TIA) in the previous 6 months
• Co-morbidities that cause pain or limit walking to a greater extent than IC (e.g. severe arthritis)
• >20% variation in baseline ACD on treadmill
• Severe peripheral neuropathies above the ankle.
• Participation in another research protocol