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Advancements in the treatment of cardiovascular disease (CVD) has led to improved prognosis in recent years; however, healthcare utilization and costs has also increased (1-3). The World Health Organization reported that annual medical spending on CVD is expected to reach $818 billion by 2030. 

Exacerbation is common in this population and further reduces physical function, leading to increased hospital readmission risk and costs (1-4). Physical therapists play a key role in improving physical function which significantly reduces the risk of readmission and improves quality of life.

It is important that PTs are able to measure functional capacity and identify high risk patients with CVD, heart failure, and other cardiac conditions as well as those with chronic respiratory disease. While a maximal test such as the cardiopulmonary exercise test holds the place as the gold standard in this type of evaluation, performing this test is not always feasible. An alternative that is easy to administer with minimal equipment is the 6-minute walk test (6MWT). 

The value of the 6MWT test goes beyond measures for cardiac and respiratory concerns. Today, this test is administered to monitor aspects of health and functional status as well as determine effectiveness of interventions in a wide array of populations.

Which Patients is the 6 Minute Walk Test Used For?

To be clinically useful for a given patient population, an outcome measure must first be reliable. That is, the test must produce consistent results under different conditions (i.e., over time, by different different clinicians).

The 6MWT has acceptable (ICC>0.8) test-retest reliability for:

  • Alzheimer’s Disease/Dementia (5,6)
  • Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) (7)
  • Chronic Obstructive Pulmonary Disease (COPD) (8)
  • Community-Dwelling Older Adults (9)
  • Coronary Artery Disease (10)
  • Duchenne Muscular Dystrophy (11)
  • Heart Failure (12)
  • Huntington Disease (13)
  • Kidney Disease on Hemodialysis (14)
  • Multiple Sclerosis (15)
  • Myasthenia Gravis 16)
  • Parkinson’s Disease (17)
  • Stroke (18)
  • Total Hip/Knee Replacement (19)
  • Traumatic Brain Injury (20)

What Does the 6 Minute Walk Test Measure?

The 6MWT can be used for a variety of purposes, from response to therapy to indications of disease severity and predictions of mortality.

As a measure of functional status, the 6MWT is useful for:

  • Acute respiratory distress syndrome (ARDS)
  • Cardiac surgery
  • COPD
  • Coronary artery disease
  • Heart failure
  • Hip fracture
  • Older adults (age 60-101)
  • Osteoarthritis
  • Peripheral arterial disease
  • Pulmonary arterial hypertension

6MWT can be used as a predictive measure of hospitalization, poor outcomes, mortality and/or morbidity in:

  • Cancer
  • Cardiac surgery
  • COPD
  • Heart failure 
  • Peripheral arterial disease 
  • Pulmonary hypertension
  • Restrictive lung disease

The test can help indicate progress and performance in response to certain therapies, as well:

  • Acute respiratory distress syndrome (ARDS)
  • Cardiac surgery
  • CIDP
  • COPD
  • Coronary artery disease
  • Heart failure
  • Muscular Dystrophy

How to Administer the 6 Minute Walk Test

Administering the 6MWT requires attention but is relatively straightforward and requires minimal equipment. A physical or occupational therapist can perform the test almost anywhere, from a corridor to a patient’s own home, as long as there is enough clear walkway to set up a track. It is not recommended to perform the 6 MWT outdoors if it can be avoided.

Ideally, the path will be 50 to 100 feet but should be at least 3 meters or 9.8 feet. Measurement of the path will be important when determining results, whether by hand or using a 6-minute walk test calculator.

Equipment Needed for the 6-Minute Walk Test

  • Markers for the path’s endpoints: these could be almost anything that won’t get in the way, from small playground cones to chairs.
  • A means of measuring the distance between endpoints of the path: a tape measure or even squares of tile can help measure the distance.
  • Timing device: A stopwatch or watch.
  • A chair for resting, if needed.

Setting up the 6-Minute Walk Test

  1. Measure and mark the walking path.
  2. Set the patient up to begin at one end of the marked path.
  3. Upon the nurse or therapist saying “Go”, the timer should be started and the patient will walk back and forth between the marked endpoints for 6 minutes.
  4. The patient may stop during the test if they need to rest, but the timer should continue to run.
  5. When the time is complete, the patient should stop where they are. Measure the final distance and allow the patient to rest.

If you will be administering the test more than once on the same day the patient should be given a 30-minute break between tests.

Which Actions Should the Clinician Take During the 6-Minute Walk Test?

As the practitioner administering the test, you should plan to do the following:

  1. Keep an eye on the time.
  2. Monitor the patient closely for distress.
  3. Keep a chair at hand in case the patient needs to rest during the test.
  4. Ensure measurements – distance, time, etc. – are recorded and computed accurately.
  5. At the end of each minute, give the patient encouragement without indicating performance, and inform them of the time remaining. For instance, you could say:
    – “You’ve got 5 minutes remaining. You’re doing well.”
    – “Good job. You have 4 minutes remaining.”
    – and so on.
  6. Make sure that the patient stops in place at the end of the 6 minutes.

Interpreting Test Results 

Six-minute walk test norms are variable by population demographics, physical attributes, track size, and presenting conditions. For instance, patients who walked in one direction on a track tended to walk further distances than those asked to walk back and forth (Scivoletto et al, 2011). Re-tests should be performed in a manner consistent with the initial testing.

Normative Data

The following scores are considered “worse than average” for their respective age groups: (Lusardi et al, 2003)

  • 60-69 yrs: < 420 meters 
  • 70-79 yrs: < 439 meters
  • 80-89 yrs: < 292 meters
  • 90-101 yrs: < 265 meters

Cut-Off Scores

Chronic Obstructive Pulmonary Disorder (COPD)

  • <350 meters is associated w/ increased mortality, airflow limitation, dyspnea, depressive symptoms, & overall poor prognosis (Spruit et al, 2010).

Heart Failure

  • Those who walk <522 meters are more likely to develop functional impairment (Costa et al, 2014)
  • <468 meters is associated with ~3x greater risk of hospitalization or death in one year (Wergrzynowska-Teodorcyk, 2013; Ferreira, 2019)

Left Ventricular Assist Device (LVAD)

  • <300 meters is associated with poor exercise tolerance, worse quality of life; higher frequencies of bleeding, infection, right heart failure, & cardiac arrhythmias post-operatively 
  • Each 10 meters less than <300 meters is associated with 21% greater risk of mortality (Hasin et al, 2012)

Lung Cancer

  • <305 meters is predictive of unsuccessful surgical outcome after pulmonary resection surgery (≤90 day survival) (Holden, 1992)

Pulmonary Hypertension

  • <332 meters is associated with significantly lower 2-yr survival rate (Miyamoto et al, 2000)

Stroke

  • Those walking <205 meters are likely limited to household ambulation; require assistance for community mobility (Fulk et al, 2017)

Accurate measurement is key to identifying high risk patients, developing a plan of care, and determining treatment efficacy. While it’s possible to use pencil and paper, there are readily available 6MWT calculators available for mobile devices that can remove the time and energy required to perform calculations, interpret results, and document findings.

Measuring up the value of physical therapy

A Leading Tool In Quality Care & Outcome Measures





References

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