Objective assessment of the response to treatment of severe heart failure using a 9-minute walk test on a patient-powered treadmill

Treadmill walking speed and survival prediction in men with cardiovascular disease: a 10-year follow-up study

OBJECTIVE

To determine whether the walking speed maintained during a 1 km treadmill test at moderate intensity predicts survival in patients with cardiovascular disease.

DESIGN

Population-based prospective study.

SETTING

Outpatient secondary prevention programme in Ferrara, Italy.

PARTICIPANTS

1255 male stable cardiac patients, aged 25-85 years at baseline.

MAIN OUTCOME MEASURES

Walking speed maintained during a 1 km treadmill test, measured at baseline and mortality over a median follow-up of 8.2 years.

RESULTS

Among 1255 patients, 141 died, for an average annual mortality of 1.4%. Of the variables considered, the strongest predictor of all-cause mortality was walking speed (95% CI 0.45 to 0.75, p<0.0001). Based on the average speed maintained during the test, participants were subdivided into quartiles and mortality risk adjusted for confounders was calculated. Compared to the slowest quartile (average walking speed 3.4 km/h), the relative mortality risk decreased for the second, third and fourth quartiles (average walking speed 5.5 km/h), with HRs of 0.73 (95% CI 0.46 to 1.18); 0.54 (95% CI 0.31 to 0.95) and 0.20 (95% CI 0.07 to 0.56), respectively (p for trend <0.0001). Receiver operating curve analysis showed an area under the curve of 0.71 (p<0.0001) and the highest Youden index (0.35) for a walking speed of 4.0 km/h.

CONCLUSIONS

The average speed maintained during a 1 km treadmill walking test is inversely related to survival in patients with cardiovascular disease and is a simple and useful tool for stratifying risk in patients undergoing secondary prevention and cardiac rehabilitation programmes.

Walking tests during the exercise training: specific use for the cardiac rehabilitation

Walk tests, principally the six-minute walk test (6mWT), constitute a safe, useful submaximal tool for exercise tolerance testing in cardiac rehabilitation (CR). The 6mWT result reflects functional status, walking autonomy and efficacy of CR on walking endurance, which is more pronounced in patients with low functional capacity (heart failure - cardiac surgery). The 6mWT result is a strong predictor of mortality. However, clinically significant changes and reliability are still subject to debate - probably because of the ambiguity in terms of the target speed (either comfortable or brisk walking). Of the other time-based walk tests, the 2-minute-walk test is the only one applicable during CR, reserved for patients with severe disabilities by its psychometric properties. Fixed-distance tests (principally the 200m fast walk test) and incremental shuttle walking, tests explore higher levels of effort and may represent a safe and inexpensive alternative to laboratory-based tests during CR. These walking tests may be useful for personalizing prescription of training programs. However, the minimum clinically significant difference has not yet been determined. Lastly, walking tests appear to be potential useful tools in promoting physical activity and behavioural changes at home. Thus, validation of other walk tests with better psychometric properties will be necessary.

Drug therapy in chronic heart failure

Chronic heart failure is widely recognised as a common and escalating problem that causes major disability and often shortens life. Diuretics and digoxin have formed the mainstay of treatment for many years. Clinical trials have demonstrated that angiotensin converting enzymes and beta-blockers, in selected patients, improve symptoms and reduce mortality. Angiotensin-II antagonists and spironolactone may also have a role in certain individuals. Newer pharmacological approaches to the management of this complex disease are being developed, but await full evaluation.

The 2-minute walk test as a measure of functional improvement in persons with lower limb amputation

OBJECTIVE

To determine the construct validity and responsiveness of the 2-minute walk test as a measure of function in individuals with lower extremity amputation.

DESIGN

The distances walked in 2 minutes were compared with the results on the physical functioning subscale of the Medical Outcomes Study Short-Form 36-Item Health Survey (SF-36) and the Houghton Scale.

SETTING

Regional amputee rehabilitation program.

PATIENTS

Retrospective data from 290 patients (mean age, 66yr) with unilateral transtibial, unilateral transfemoral, or bilateral amputations.

INTERVENTION

Repeated testing.

MAIN OUTCOME MEASURES

Distance walked in 2 minutes, SF-36 (aggregated into physical and mental composite scores), and the Houghton score. We also examined the change in the distance before and after a rehabilitation program.

RESULTS

The distance walked in 2 minutes showed a weak correlation with the physical functioning subscale of the SF-36 (r = .22, p = .008) and a moderate correlation with the total Houghton score at discharge from rehabilitation (r = .493, p <or= .001). The correlation between distance walked in 2 minutes and SF-36 physical functioning subscale at follow-up was moderate (r = .479, p < .001). There was a significant improvement in distance walked in 2 minutes at discharge and follow-up compared with baseline (mean change +/- standard deviation at discharge, 13.6 +/- 19.9m; at follow-up, 41.2 +/- 34m, p < .001).

CONCLUSION

The 2-minute walk test was responsive to change with rehabilitation in persons with lower extremity amputation. In addition, the 2-minute walk test showed adequate correlation with measures of physical functioning and prosthetic use in this population.

A qualitative systematic overview of the measurement properties of functional walk tests used in the cardiorespiratory domain

OBJECTIVE

To perform a qualitative systematic overview of the measurement properties of the most commonly utilized walk tests in the cardiorespiratory domain: the 2-min walk test (2MWT), 6-min walk test (6MWT), 12-min walk test (12MWT), self-paced walk test (SPWT), and shuttle walk test (SWT).

DATA SOURCES

MEDLINE (1966 to January 2000) and CINAHL (1982 to December 1999) electronic databases were searched. Bibliographies of the retrieved articles were reviewed.

STUDY SELECTION

Clinical trials and observational studies were included if they reported data on the validity, reliability, interpretability, or responsiveness of the 2MWT, 6MWT, 12MWT, SPWT, or SWT. Only studies conducted on patients with cardiac and/or respiratory involvement were included.

RESULTS

Fifty-two studies examining measurement properties of the various walk tests were found: 5 studies on the 2MWT, 29 studies on the 6MWT, 13 studies on the 12MWT, 6 studies on the SPWT, and 4 studies on the SWT. Measurement properties were most strongly demonstrated for the 6MWT. Correlations of 6MWT distance and maximal oxygen consumption ranged from 0.51 to 0.90. A change in distance walked of at least 54 m was found to be clinically significant for the 6MWT. Reliability was shown to be optimized when the administration of walk tests was standardized and at least two practice walks were performed. Patients with increased likelihood of postoperative complications, hospitalization, and death were identified by analysis of distance walked.

CONCLUSIONS

Measurement properties of the 6MWT have been the most extensively researched and established. In addition, the 6MWT is easy to administer, better tolerated, and more reflective of activities of daily living than the other walk tests. Therefore, the 6MWT is currently the test of choice when using a functional walk test for clinical or research purposes.

Simple methods of assessing physical activity in patients with chronic heart failure

This article reviews simple, noninvasive ways to assess physical activity in patients with chronic heart failure. Six- or 9-minute walk tests appear to be useful not only for selecting patients with relatively advanced heart failure but also as prognostic screening tests. The Master-Borg test (Master's two-step testing and 10-point Borg scale) is useful for assessing symptoms during exercise. Weekly pedometer counts show that the level of activity in patients with heart failure is dramatically less than in healthy controls. Physical activity can be determined directly by an ambulatory calorie counter that measures step scores and energy expenditure using specific accelerometers. Careful clinical interviewing regarding symptoms, together with submaximal exercise testing and use of motion sensors, are recommended as useful, simple, noninvasive alternatives for assessing physical activity in this patient population. (c)2000 by CHF, Inc.