# Exercise as it relates to Disease/Does a home based exercise program improve physical activity levels in patients with Peripheral Artery Disease?

This is a critical analysis of the journal article "Home-Based Walking Exercise Intervention in Peripheral Artery Disease: A Randomized Clinical Trial" by McDermott et al in 2013.

### What is the background to this research?
##### Epidemiology

* Peripheral Artery Disease (PAD) refers to the restriction of blood flow into the arteries in any area of the body other than the intracranial or coronary regions.
* PAD is most commonly reported in the lower limbs, with or without the presence of intermittent claudication, which is a painful cramping sensation in response to reduced blood flow, often experienced in the calves, hamstrings or buttocks.
* The most common cause of PAD is atherosclerosis, which is the buildup of plaque within arterial walls.
* PAD has been associated with a variety of lifestyle restrictions including decreased mobility and loss of work and has also been linked with increasing the risk of myocardial infarction, stroke and permanent disability or death.

##### Risk Factors

Risk factors for PAD can be split into two categories, these being modifiable and non-modifiable.
Modifiable risk factors include:
* Hypertension
* Hypocholesteremia
* Diabetes
* Smoking
Non modifiable risk factors comprise
* Gender
* Genetics
* Age

##### Background Research

Several studies have reported the decrease in mobility associated with PAD to be one of the largest impactors on physical functioning in sufferers, and the same research found that an exercise program was successful in improving functional status in PAD patients.

### Where is the research from?

* The research was conducted at various institutions within Chicago, Illinois between July 22, 2008, and December 14, 2012
* The lead researcher, Professor Mary M. McDermott was based out of the Northwestern University Feinberg School of Medicine, and has previously published multiple high quality papers regarding PAD, and its impact on daily function.
* Funding for the paper was obtained from the National Heart, Lung, and Blood Institute, and the National Institutes of Health and Ageing.

### What kind of research was this?

* This paper is a randomized controlled clinical trial of 194 patients with PAD. The paper was scored 7/10 on the PEDro scale, indicating that it is a valid, high quality study. Various other RCT’s have also researched the benefits of exercise on PAD, enabling a body of good quality evidence to be developed.
* In 2014, a Cochrane review was published regarding the use of exercise as a treatment for PAD patients with intermittent claudication, with the authors concluding that exercise programs may be of significant benefit to patients with PAD in regards to both physical functioning and vitality.
* The results of both the high quality RCT's and the Cochrane systematic review add validity, and thus support the argument to include home based exercise in a program with PAD.

### What did the research involve?

This study involved the random allocation of patients to 1 of 2 groups: a group home-based walking intervention or a control group.

##### Design

* Participants were recruited via newspaper or radio advertisements, as well as from postcards sent to individuals aged 65 years and older in the Chicago area.
* The inclusion criterion was an ankle-brachial index (ABI) of 0.90 or less in either leg.
* Leg symptoms were characterized using the San Diego claudication questionnaire. Intermittent claudication was defined as exertional calf pain that does not begin at rest, causes the participant to stop walking, and resolves within 10 minutes of rest.
* All outcomes were measured beforehand and at 6-month follow-up by assessors blinded to participants’ group assignment.

##### Intervention

* In the exercise group, participants met for 90 minutes once per week in a group with other PAD participants for the 6 month duration of the intervention. Groups were led by a trained facilitator and involved 45 minutes of facilitator-led discussions and 45 minutes of walking around an indoor track.
* The control group attended 60 minute group sessions once per week where physicians and other health care professionals provided lectures on topics including managing hypertension, cancer screening, and vaccinations.

##### Outcomes

* Change in 6-minute walk performance between baseline and 6-month follow-up was used as the primary outcome.
* Secondary outcomes were changes in maximal treadmill walking time, pain-free treadmill walking time, physical activity, the Walking Impairment Questionnaire (WIQ) scores, and the Physical Health Composite Score (PCS)

### What were the basic results?
##### Primary Outcome

Participants randomized to the exercise intervention group significantly increased their 6-minute walk distance from 357.4 to 399.8 metres, compared to 353.3 to 342.2 metres for those in the control group at the 6 month follow up.

##### Secondary Outcomes

The following outcome measures also showed statistically significant improvement within the intervention group with respect to the control group:
* Maximal treadmill walking time
* Accelerometer-measured physical activity over 7 days
* WIQ distance score
* WIQ speed score
The PCS scores showed no significant difference between groups.
Improvements in 6MWT distance have been linked to improved quality of life and decreased risk of cardiovascular events and mortality in PAD sufferers

### What conclusions can we take from this research?

The results of this paper support the use of a home based over ground walking program for PAD patients, and this is backed up by reviewing the outcomes from the larger body of literature. The general consensus from the literature however, suggests that whilst over ground walking may result in greater functional improvements than treadmill walking, any form of physical activity can be useful in limiting adverse outcomes associated with PAD and improving patient function.

##### Implications

The implications of this when placed within the body of literature, are that whilst the majority of patients will benefit from a prescribed overground walking program, in some instances the clinician may be better served prescribing treadmill or resistance training as an alternative if a particular patient is more inclined to perform these methods of exercise.

### Practical advice

An exercise program of some form should be implemented with all PAD patients regardless of ability or fitness level. Overground walking training appears to elicit greater function gains than treadmill training, however both improve function. For clinicians who are limited by time or access to their patients, a home based walking training program would be an appropriate way to increase physical activity and functional performance without requiring intensive face to face interaction.

### Further information/resources

* Healthdirect: https://www.healthdirect.gov.au/peripheral-vascular-disease
* Royal Australian College of General Practitioners: http://www.racgp.org.au/download/Documents/AFP/2013/June/201306au.pdf
* Australia and New Zealand Society for Vascular Surgery: http://www.anzsvs.org.au/patient-information/intermittent-claudication-peripheral-vascular-disease
* American Society of Vascular Surgeons: https://vascular.org/patient-resources/vascular-conditions/peripheral-arterial-disease
* American Heart Association: http://www.heart.org/HEARTORG/Conditions/VascularHealth/PeripheralArteryDisease/Peripheral-Artery-Disease-PAD_UCM_002082_SubHomePage.jsp

### References

* 1 2 3 4 5 6 7 8 9 10 11 McDermott, M., Liu, K., Guralnik, J., Criqui, M., Spring, B., Tian, L., Domanchuk, K., Ferrucci, L., Lloyd-Jones, D., Kibbe, M., Tao, H., Zhao, L., Liao, Y. and Rejeski, W. (2013). Home-Based Walking Exercise Intervention in Peripheral Artery Disease. JAMA, 310(1).
* 1 2 3 Garcia, L. (2006). Epidemiology and Pathophysiology of Lower Extremity Peripheral Arterial Disease. Journal of Endovascular Therapy, 13(1).
* ↑ Anzsvs.org.au. (2017). Intermittent Claudication & Peripheral Vascular Disease | Australian & New Zealand Society for Vascular Surgery. [online] Available at: http://www.anzsvs.org.au/patient-information/intermittent-claudication-peripheral-vascular-disease/ [Accessed 24 Sep. 2017].
* 1 2 3 Selvin, E. (2004). Prevalence of and Risk Factors for Peripheral Arterial Disease in the United States: Results From the National Health and Nutrition Examination Survey, 1999-2000. Circulation, 110(6).
* ↑ Hirsh, A., Criqui, M. and Treat-Jacobson, D. (2002). Peripheral arterial disease detection, awareness, and treatment in primary care. ACC Current Journal Review, 11(1).
* 1 2 National Heart, Lung and blood institute. (2014). What is peripheral arterial disease. Retrieved 20/9, 2014, from http://www.nhlbi.nih.gov/health/health-topics/topics/pad/
* 1 2 3 4 Hiatt, W., Regensteiner, J., Hargarten, M., Wolfel, E. and Brass, E. (1990). Benefit of exercise conditioning for patients with peripheral arterial disease. Circulation, 81(2), pp.602-609.
* 1 2 3 4 Regensteiner, J., Steiner, J. and Hiatt, W. (1996). Exercise training improves functional status in patients with peripheral arterial disease. Journal of Vascular Surgery, 23(1), pp.104-115.
* 1 2 Nehler, M., McDermott, M., Treat-Jacobson, D., Chetter, I. and Regensteiner, J. (2003). Functional outcomes and quality of life in peripheral arterial disease: current status. Vascular Medicine, 8(2), pp.115-126.
* ↑ McDermott, M., Tian, L., Liu, K., Guralnik, J., Ferrucci, L., Tan, J., Pearce, W., Schneider, J. and Criqui, M. (2008). Prognostic Value of Functional Performance for Mortality in Patients With Peripheral Artery Disease. Journal of the American College of Cardiology, 51(15), pp.1482-1489.
* ↑ McDermott, M., Ohlmiller, S., Liu, K., Guralnik, J., Martin, G., Pearce, W. and Greenland, P. (2001). Gait Alterations Associated with Walking Impairment in People with Peripheral Arterial Disease with and without Intermittent Claudication. Journal of the American Geriatrics Society, 49(6), pp.747-754.
* ↑ de Morton, N. (2009). The PEDro scale is a valid measure of the methodological quality of clinical trials: a demographic study. Australian Journal of Physiotherapy, 55(2), pp.129-133.
* 1 2 3 Lane, R., Ellis, B., Watson, L. & Leng, G., 2014. Exercise for intermittent claudication. The Cochrane Library.
* 1 2 3 Hamburg, N. and Balady, G. (2011). Exercise Rehabilitation in Peripheral Artery Disease: Functional Impact and Mechanisms of Benefits. Circulation, 123(1), pp.87-97.