Reliability, Validity, and Responsiveness of a 2-Min Walk Test To Assess Exercise Capacity of COPD Patients: Study Design

The exclusion criteria included dementia, concomitant heart failure, diseases with mobility impairment, and medical conditions that were contraindicated for exercise testing according to American Thoracic Society (ATS) guidelines., After completing the data collection for the first part of the study, 15 of these patients joined a 5-week intensive pulmonary rehabilitation program and were recruited into the second part of study. The program consisted of educational and aerobic exercise components as well as components of relaxation and coping skills in activities of daily living in each session. The patients attended the hospital 3 days a week (from 9:00 am to 3:00 pm). Training strategy and intensity were individually tailored according to patients’ goals and abilities. All patients were required to give written consent before the study. The study was approved by the research ethics committees of the Haven of Hope Hospital and the University of Chester. Link

A prospective correlational study design was selected. Demographic and anthropomorphic data were collected (ie, age, gender, body weight, height, body mass index [BMI], and dominant hand grip strength). Two walking tests (the 2MWT and the 6MWT), a pulmonary function test, and a maximal cardiopulmonary exercise test (CPET) on a cycle ergometer were conducted in random order within a 5-day period. The 2MWT was repeated three times in order to examine its reliability. The results from the 2MWT were correlated with those of the 6MWT and the CPET (ie, Vo2max, Vo2max per kilogram, and maximum work capacity [Wmax]) for validation evaluation. For the evaluation of responsiveness, the 2MWT and 6MWT were conducted at the start and at the end of the pulmonary rehabilitation program for comparison.
Demographics and Anthropomorphic Assessment: Body weight (in kilograms) and height (in meters) were recorded, and the BMI (in kilograms per square meter) was calculated.
Pulmonary Functions Assessment: Pulmonary functions were assessed (Pulmonary Diagnostic Systems model PF/DX; Medical Graphics Corp; St. Paul, MN). FVC and FEV1 were determined from three trials, and the values for FVC and FEV1 were selected that fulfilled the reproducibility and acceptability criteria in accordance with the ATS criteria. Lung volumes, including residual volume and total lung capacity, were measured with a body plethysmograph, and diffusion capacity of the lung for carbon monoxide was measured by the single-breath technique. Absolute values and percentages of predicted values of the lung function parameters were used for analysis.