Determinants of Physical Activity in Peripheral Arterial Disease

Principal Investigator: Andrew Gardner, Ph.D.

Abstract:

The proposed study will focus on patients with critical limb-threatening ischemia (i.e., Fontaine Stage III and Stage IV PAOD) who undergo lower extremity revascularization for limb salvage, and who usually have subsequent improvement in their symptomatology to Stage II PAOD (i.e., intermittent claudication).  Although exercise rehabilitation is recommended as a therapy to treat intermittent claudication and improve ambulation in patients with stable claudication,3 little data is available on the efficacy of exercise rehabilitation in PAOD patients with critical limb-threatening ischemia whose disease and symptoms are upgraded to Stage II PAOD (intermittent claudication) following lower extremity revascularization.  Our preliminary data indicates that similar relative gains in claudication distances, free-living daily physical activity, health-related quality of life, peak oxygen uptake, walking economy, and peripheral circulation are achieved following a program of exercise rehabilitation in a small group of physically deconditioned, revascularized PAOD patients (section 3.3).

Specific Aims:

To identify the determinants of daily physical activity in subjects with peripheral arterial disease (PAD).

            1. Severity of claudication pain, vascular impairment in the lower extremities, and current cigarette smoking will each be related to decreasing levels of daily physical activity in PAD subjects and the relationship for each one will remain apparent even after adjustment for other two.

            2. Furthermore, markers of functional dependence, such as declines in strength, balance, ambulatory speed, as well as poor self-perceived measures of ambulatory function, health, quality of life, and exercise efficacy expectations will be additional independent predictors of declining levels of daily physical activity after the measures of disease severity and smoking status are controlled.

This is a two-visit, cross-sectional study in which the lower extremities will be evaluated for the presence and severity of PAD using non-invasive Doppler blood pressure measurements.  Additional tests and questionnaires during the first visit will assess physical function, vascular function, and health-related quality of life in PAD subjects.  At the end of the first visit, subjects will have two physical activity monitors placed on their waist and ankle to wear for at least two days.  The second visit will be arranged to return the physical activity monitors, and to complete any measurements that were missed during your first visit.

Participant Inclusion Criteria:

Study Population: Men and women of any race between 40 and 90 years of age with documented or suspected PAD will be recruited for this study. 

The inclusion criterion include:

1. presence of PAD defined as an ABI value at rest < 0.90
2. living independently at home. 

The exclusion criteria include:

1. poorly controlled hypertension (resting systolic blood pressure > 200 mm Hg or resting diastolic blood pressure > 120 mm Hg)
2. unstable angina, and cognitive dysfunction (mini-mental state examination score < 24). 

The duration of participation in this study is two visits in which the first visit includes all laboratory assessments and placing two physical activity monitors on the subjects, and the second visit includes removal of the two monitors, completing any measurements that were missed during the first visit, and to give subjects a report on their performance of the various tests.  If subjects decline wearing the physical activity monitors, the study will conclude following the first visit. 

The study will be terminated early if the subject declines participating in any of the remaining tests, or if the test administrator believes that it is in the best medical interest of the subject not to participate.  Subjects who have a high risk for falls due to gait and standing instability, and who do not have an assitive device present for the testing will not be asked to perform the physical function tests (i.e., 4-meter walk test, tandem stance test, unipedal stance test, chair stand test, and timed-up-and-go test).  Furthermore, subjects who have an upper respiratory infection will not be asked to perform the spirometry tests.

Participant Compensation: Yes or No

Contact Information:

Kristy Scott, GCRC Exercise Physiologist. (405) 271-4272 x 42742 or kristy-scott@ouhsc.edu When inquiring, please mention the Physical Activity Study at the General Clinical Research Center.