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Background: The six-minute stepper test (6MST) is a self-paced test considered a valid tool to assess functional capacity in stable COPD patients. However, a high floor effect, where a large proportion of participants reach the minimum score when using the measurement instrument, might compromise the test validity in the hospital setting. Therefore, this study aimed at verifying the concurrent validity of 6MST in hospitalized patients with acute exacerbation of COPD (AECOPD). Methods: A cross-sectional study was conducted in a tertiary hospital. Patients who were hospitalized due to AECOPD were considered for inclusion. On the first day, when patients reached minimum clinical criteria considered as the use of non-invasive ventilation less than 2 h for 6 h/period, dyspnea at rest less than 7 (very severe) on the modified Borg scale, a respiratory rate less than 25 breaths per minute, oxygen pulse saturation greater than 88% (considering use of supplemental oxygen) and absence of paradoxical breathing pattern, they underwent a lung function evaluation and answered three questionnaires: Chronic Respiratory Questionnaire (CRQ), Modified Medical Research Council Dyspnea Scale (MMRC), and COPD Assessment Test (CAT). Then, on two consecutive days, patients performed 6MST or six-minute walk test (6MWT), in random order. Each test was performed twice, and the best performance was recorded. Also, the patient's severity was classified according to the BODE index. Inspiratory capacity measurements were performed before and after each test execution. Results: Sixteen patients (69.4 ± 11.4 years) with a mean FEV1 of 49.4 ± 9.9% predicted were included (9 females). There was a strong correlation of the performance in 6MST (number of cycles) with 6MWT (distance walked in meters) in absolute values (r = 0.87, p < 0.001) as well as with the percentage of predicted normal 6MWT (r = 0.86, p < 0.001). There was a strong correlation between the performance in 6MST with the dynamic hyperinflation (r = 0.72, p = 0.002) and a moderate correlation between 6MST with the percentage of reduction of inspiratory capacity (r = 0.68, p = 0.004). We also identified that 6MST showed moderate negative correlations with CAT (r = -0.62, p = 0.01) and BODE index (r = -0.59, p = 0.01). Conclusion: It could be concluded that 6MST is valid for evaluating functional capacity in hospitalized patients with exacerbated COPD.
RESUMO
OBJECTIVE: To evaluate the convergent validity of the six-minute stepper test (6MST) with the variables used in the diagnosis of sarcopenia (appendicular muscle mass, handgrip strength and six-meter gait speed test), as well as to evaluate test-retest reliability and safety when applied to hospitalized elderly patients. Finally, we aimed to compare the performance in the 6MST between hospitalized elderly patients and healthy elderly from the community. MATERIALS AND METHODS: Observational and cross-sectional study. Elderly patients admitted to a private hospital and healthy elderly from the community were recruited. On the first day, the patients included underwent the following assessments: anthropometric, handgrip strength (HGS), six-meter gait speed test (6GST) and 6MST. On the second day, before breakfast, patients underwent body composition assessment. The healthy elderly were evaluated on a single day and performed only anthropometric assessment and 6MST. RESULTS: 30 hospitalized patients (age 71.0±7.9 years) and 15 healthy elderly (age 68.1±5.8 years) were included. There was a high correlation of 6MST with 6GST (r = 0.78; p<0.001), moderate correlation with HGS (r = 0.59; p<0.001) and low correlation with appendicular muscle mass (r = 0.45; p = 0.01). There was no statistical difference between the first and second 6MST performed by hospitalized elderly (196.2±91.0 cycles vs. 191.3±103.7 cycles; p = 0.66), in addition to an excellent agreement between these measures (ICC = 0.90; 95% IC 0.78-0.95). Only one adverse event (3.3%) occurred in the sample. CONCLUSION: 6MST showed convergent validity with the functional variables used in the diagnosis of sarcopenia. In addition, excellent test-retest reliability was observed, which indicates the need for a single assessment in hospitalized elderly patients. The prevalence of adverse events during the application of the test is low, without resulting in clinical symptoms; therefore, the test is considered safe for this population. In addition, hospitalized elderly patients perform worse in the 6MST compared to healthy elderly from the community.