Reliability, Validity, and Responsiveness of a 2-Min Walk Test To Assess Exercise Capacity of COPD Patients: Subjects
A 2-min walk test (2MWT) was first proposed by Butland et al in 1982 and was reported to be a valid test in COPD patients. However, the statistical method was in doubt as no p value had been mentioned in the whole study and only 13 subjects were recruited. A small-scale study (n = 9) performed by Bernstein et al in 1994 also reported on the validity and responsiveness of the 2MWT. However, the results should be interpreted with caution because the authors compared the distance walked in a 2-min interval of the 12MWT. It was argued that the distance covered in a 2-min interval of a 12MWT might be different from the distance walked in a 2MWT, as the pacing by the subjects might be different for the two different intervals. It was reported that a patient who knew that a walk test would only last for 2 min would walk further than a patient would in the first 2 min of a longer walk test. A more recent study by Eiser et al reported that the 2MWT was a reliable test and was sensitive to change after bronchodilator therapy.
However, the patients’ performance may have been greatly influenced by the investigators as the investigators walked in front of the patients during the tests. A few studies of 2MWT in other populations including children with cystic fibrosis, frail elderly persons, and those patients having undergone amputation have been conducted. Since both the reliability and validity of a test are population-specific, and the responsiveness of the 2MWT to rehabilitation is lacking, this study was designed to investigate the reliability and validity of the 2MWT as well as its responsiveness to change following a pulmonary rehabilitation program. More info
This study consisted of the following two parts: first, to evaluate the reliability and validity of the 2MWT; and second, to evaluate the responsiveness of the 2MWT to pulmonary rehabilitation. Forty-seven COPD patients were recruited from the outpatient pulmonary clinic and waiting list for the pulmonary rehabilitation program in Haven of Hope Hospital. The inclusion criteria included the following: (1) moderate-to-severe COPD; (2) stable condition without experiencing an acute exacerbation in the month prior to or during the study; (3) no change in medications during the study; and (4) no requirement for long-term oxygen therapy.