Efficacy and Mechanism Evaluation (Jul 2023)
Neuromuscular electrical stimulation as an adjunct to standard care in improving walking distances in intermittent claudication patients: the NESIC RCT
Abstract
Background Peripheral arterial disease is common and associated with increased cardiovascular morbidity and mortality. While patients with peripheral arterial disease are known to benefit from supervised exercise therapy, it is not always available. Neuromuscular electrical stimulation devices may offer a similar benefit. A randomised controlled trial was required to ascertain whether such devices can benefit patients who receive supervised exercise therapy and those who do not. Objective(s) The primary objective was to assess the mean difference in absolute walking distance at 3 months in intermittent claudication patients receiving either a neuromuscular electrical stimulation device and local standard care (intervention), or local standard care alone (control). Design A pragmatic, multicentre, randomised controlled trial stratified by centre. Setting Secondary-care National Health Service hospitals in the United Kingdom. Participants Patients aged ≥18 years, with a diagnosis of intermittent claudication according to the Edinburgh Claudication Questionnaire and ankle–brachial pressure index (or stress test), without contraindications to neuromuscular electrical stimulation were deemed eligible to partake. Interventions Participants were randomised 1 : 1 to either local standard care or local standard care and neuromuscular electrical stimulation. Due to the nature of the intervention, it was unfeasible to blind the research nurse or participant to the study allocation. Main outcome measures The primary outcome measure was absolute walking distance measured by treadmill testing at 3 months. Secondary outcomes included change in initial claudication distance, quality of life, compliance with interventions and haemodynamic assessments. Results Two hundred patients underwent randomisation, with 160 patients having analysable primary outcome data for the intention-to-treat analysis intervention (n = 80); control (n = 80). As the data were right-censored, a Tobit regression model was used to analyse the primary outcome, utilising the square root of the absolute walking distance to accommodate the skewed data. However, as this made the data difficult to interpret, a Tobit regression model using raw absolute walking distance data was used as well. Neuromuscular electrical stimulation improved the difference in absolute walking distance at 3 months but this was not statistically significant (square root of absolute walking distance: 0.835 units, 95% confidence interval −0.67 to 2.34 units; p = 0.28/absolute walking distance raw data: 27.18 m, 95% confidence interval −26.92 to 81.28 m; p = 0.323). Supervised exercise therapy participants showed a markedly improved absolute walking distance compared with patients receiving best medical therapy only at 3 months (square root of absolute walking distance: 3.295 units 95% confidence interval 1.77 to 4.82; p 30 mmHg, 40 seconds post 1 minute treadmill at 10% gradient, 4 km/hour) •able to give informed consent to participate in the trial after reading the patient information documentation •age ≥18 years. Exclusion criteria •severe IC requiring invasive intervention as determined by the treating clinician •critical limb ischaemia as defined by the European Consensus Document •comorbid disease prohibiting walking on a treadmill or taking part in SET •able to walk for longer than 15 minutes on the study treadmill assessment •have attended SET classes in the previous 6 months •popliteal entrapment syndrome •commenced vascular-symptom-specific medication in previous 6 months – for example, naftidrofuryl oxalate, cilostazol •pregnancy •any implanted electronic, cardiac or defibrillator device •acute deep vein thrombosis •broken or bleeding skin, including leg ulceration •peripheral neuropathy •recent lower-limb injury or lower back pain •already using a NMES device. Randomisation Randomisation (1 : 1) was web-based and hosted by Oracle Health Sciences InForm™ (Oracle®; Health Sciences, Austin, TX, USA) electronic data capture on an Oracle platform. Randomisation used random block size and was stratified by centres. Interventions The NMES device (REVITIVE IX) can be used in the patient’s own home. It delivers a 30-minute pre-programmed session of electrical stimulation to the lower-limb muscles through foot pads while the patient is in a seated position. The user controls the intensity of the impulses, and therapeutic benefit is deemed to occur when impulses are sufficient to cause contraction of the calf muscles, increasing venous return to the heart. The IsoRocker feature allows the device to tilt back and forth as the muscles contract and relax. The device is to be used for at least one 30-minute session daily (up to a maximum of six sessions) for 3 months (treatment period). Diabetic patients are to use the device for a minimum of two 30-minute sessions daily for the duration of the treatment period to better reflect the evidence supporting the diabetic patient group and improvement of their symptoms. A SET programme is usually led by a physiotherapist or allied health-care provider supervising exercise, usually within the physiotherapy gymnasium with equipment including a treadmill, steps and walking cones. SET classes usually involve a circuit of lower-limb exercises, for a minimum of 30 minutes per week, and usually over a 3-month duration. Outcomes and follow-up The primary outcome was AWD at 3 months, measured by treadmill testing. Secondary outcomes included quality of life over 12 months as measured by generic health-related quality of life tools, European Quality of Life 5-Dimensions 5-Level (EQ-5D-5L®) (EuroQol Group, Rotterdam, The Netherlands), Short-Form Health Survey-36 (SF-36®) (RAND Health Care, Santa Monica, CA, USA) and the intermittent claudication questionnaire; compliance with NMES and SET as measured against self-report participant diaries and device data loggers; change in initial claudication distance measured by treadmill testing; and haemodynamic assessments measured by duplex ultrasound and laser doppler flowmetry. Participants in both groups were followed up for 12 months post randomisation. In-person visits were performed at screening/baseline (randomisation), 3 months, 6 months and 12 months. The treadmill assessment (Gardner-Skinner protocol) and laser doppler flowmetry of the foot were completed at each visit and the duplex ultrasound was performed by a vascular scientist at baseline and 3 months only. Self-report health resource-use participant diaries were completed throughout the 12-month duration of the study. Additionally, the self-report exercise diaries were completed by all participants for 3 months or for the duration of the SET programme, and the device compliance diaries were completed by participants randomised to NMES for the duration of the treatment period. A device experience questionnaire was completed at 3 months for participants in the NMES arm of the trial. The quality-of-life questionnaires were administered at baseline and each follow-up either in person, via the telephone or via post. Participant follow-up is summarised in Appendix 1. Due to the COVID-19 crisis, a substantial amendment was submitted to Ethics in April 2020 to allow all follow-up visits to take place remotely (i.e. over the telephone completely or in combination with postal questionnaires) in the event that the participant was unable to attend in clinic or the site was unable to accommodate the on-site visit. Missed (physical) assessments as a result of a remote visit were rescheduled at a later date as a separate on-site visit, where possible. If an on-site visit was rescheduled at a later date, all quality-of-life questionnaires that were completed remotely were repeated at the on-site visit. Results (research findings) Two hundred participants underwent randomisation and 160 were included in the intention-to-treat primary analysis [intervention (n = 80); control (n = 80)]. NMES improved AWD in patients with IC following the 3-month treatment period but this was not statistically significant [square root of AWD: 0.835 units, 95% confidence interval (CI) −0.67 to 2.34; p = 0.276/AWD raw data: 27.18 m, 95% CI −26.92 to 81.28; p = 0.323]. Participants who had access to a SET programme showed a clear improvement in AWD compared with patients who received BMT only at 3 months (square root of AWD: 3.295 units, 95% CI 1.77 to 4.82; p < 0.001/AWD raw data: 121.1 m, 95% CI 67.32 to 176.10; p < 0.001). Improvements in the AWD at 3 months were seen when NMES was used in combination with SET, but this was not significant (square root of AWD: 1.724 units, 95% CI −0.56 to 4.01; p = 0.137/AWD raw data: 64.26 units, 95% CI −20.03 to 148.54; p = 0.13). NMES significantly improved AWD at 3 months for patients who could walk for more than 340 m at baseline (square root of AWD: 2.877 units, 95% CI 0.51 to 5.25; p = 0.019/AWD raw data: 120.55 m, 95% CI 16.03 to 225.06; p = 0.03) compared to the control arm. Mechanistic findings of the laser doppler flowmetry found no clear differences in blood flux between the two treatment groups over the 12-month follow-up period, nor any significant differences in volume flow or time average mean velocity (duplex ultrasound) groups at 3 months. Serious adverse events (n = 29) were reported in 24 participants, with all events being classified as either not related or unlikely to be related to the study device. The number of SAEs in the treatment arm was 13 and 16 in the control arm. Most of the events required hospitalisation; there were four deaths. Conclusions The results of the NESIC trial indicate that SET is the most effective treatment option for patients with IC. Although not significant, NMES improves walking distances when used in combination with a SET programme, and significantly improves AWD in mild claudicants. Implications for health care Findings from this trial suggest that all IC patients should have access to a SET programme and changes to such programmes may need to be made to encourage and/or retain participants. NMES may be an effective adjunct to SET and in patients with a good baseline walking distance. Recommendations for research (numbered in priority order) 1.Randomised controlled trial of NMES as an adjunct to SET in IC patients stratified by baseline AWD, as the NESIC study showed promise of non-invasive effectiveness in mild and/or moderate claudicants at improving walking distances, but larger numbers are required to validate this finding. 2.Research to examine the poor patient motivation and adherence to SET, as SET is clearly an effective treatment option for claudicants as seen in this study and many other studies but uptake/compliance remains an issue. 3.Research to evaluate the long-term effectiveness of SET programmes on maximal walking distance (MWD) and secondary outcomes such as quality of life and long-term engagement in physical activity. The NESIC study showed the effectiveness of SET at 12 months at improving AWD but longer-term follow-up is required to evaluate whether this is sustained years later. Previous studies have shown mixed results on the impact of SET on other outcomes, such as quality of life, and therefore further research is required. Study registration This trial is registered as ISRCTN18242823. Funding This project was funded by the Efficacy and Mechanism Evaluation (EME) Programme, a Medical Research Council (MRC) and National Institute for Health and Care Research (NIHR) partnership (project number 15/180/68). This will be published in full in Efficacy and Mechanism Evaluation; Vol. 10, No. 2. See the NIHR Journals Library website for further project information. Infrastructure support for this research was provided by the NIHR Imperial Biomedical Research Centre (BRC) (with others, e.g. NIHR Imperial CRF, Imperial College ECMC, NIHR Imperial PSTRC, NIHR London MIC, etc.).
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