Reanalysis of the 12-Minute Walk in Patients With Chronic Obstructive Pulmonary Disease – Conclusion
It has been shown that the 12-min walking test does not correlate significantly with FEV, but there have been differing results as to whether it does2 or does not correlate with FVC. Our results support the latter finding (r = -0.16). In addition, we found that there was a significant correlation between changes in the FEVj and changes in the 12-min (r = 0.53) and changes in the 6-min (r = 0.53) walking tests.
Previous studies, as well as our own, demonstrate that the results of walking tests correlate with functional capacity as assessed by symptom-limited maximal exercise tests. However, in assessing the effects of an intervention for a given individual, it is more important to understand how changes in walking test performance correlate with the changes in the maximum exercise capacity. It would be advantageous to be able to predict the change in Vo2max, that a patient is experiencing since his last examination from his walking test alone because it precludes the necessity of using more complicated apparatuses such as a treadmill or bicycle ergometer. canadian neightbor pharmacy
Butland and coworkers have studied the usefulness of the 12-min walking test in predicting maximal ventilatory function to determine if a shorter length test could be used. Since they found the variances between 2-, 6-, and 12-min walks to be comparable, they concluded that a 6-min walk was an acceptable compromise to the 12-min walk. Our own findings suggest that the 12-min walk is superior because changes in it correlate better with changes in the maximal exercise tests than do changes in the shorter walk tests. The correlation coefficient between the percentage of change in Vo2max and the percentage of change in the 12rmin walk is 0.72, which is higher than that with the 6-min walk (0.64), the 4-min walk (0.59, or the 2-min walk (0.53).
Our study design involved data from patients who were in a study to determine the effects of buspirone on anxiety levels and exercise tolerance in patients with chronic airflow obstruction and mild anxiety. Because buspirone was seen to have an insignificant effect on walking tests, we elected to indiscriminately combine the walking test data for analysis. That is, this project did iiot make a distinction between patients who were taking buspirone and those who were receiving placebo. Although we feel comfortable with this decision, there is a remote possibility that the buspirone study and its exclusion-inclusion criteria could have affected our results.
Another possible criticism of our study was that the 12-min walk cannot be extrapolated to determine how a patient would perform on a shorter walk. It is possible that differing results would have been obtained if the patient only walked 2, 4, or 6 min. It appears that a patient who knows that a walk will only last for 2 min will walk further than a patient will in the first 2 min of a longer walk.
In conclusion, we believe that the 12-min walk is the best walking test for assessing the functional capabilities of a patient. The basis for this conclusion is our observation that changes in Vo2max correlate more closely with changes in the 12-min walking test than with changes in other walking tests.