Validity and Reliability of the 6-Minute Step Test in Healthy Individuals: A Cross-sectional Study.

OBJECTIVE: To determine the 6-minute step test's (6MST) reliability and validity and to establish reference performance values of this test. DESIGN: Prospective observational cross-sectional study. SETTING: Spirometry and Respiratory Physiotherapy Laboratory, Federal University of São Carlos (institutional). PARTICIPANTS: Ninety-one individuals [42 men and 49 women, mean age = 39 years (SD, 17 years)] without any diagnosed diseases and with normal exercise capacity [6-minute walk test (6MWT) >75% of the predicted normal]. INDEPENDENT VARIABLES: Participants underwent two 6MST on 1 day and two 6MWT on another day in randomized order. Furthermore, age, gender, height, weight, lower limbs length, abdominal circumference, percentage of body fat, and fat-free mass were obtained. MAIN OUTCOME MEASURES: Test-retest reliability was assessed by comparing the findings of the two 6MST using the intraclass correlation coefficient (ICC) and Bland-Altman plot. Validity was assessed by comparing outcomes of the 6MST to outcomes of 6MWT using the Pearson correlation coefficient. A multiple regression analysis was conducted using the stepwise method to develop an equation to predict reference values. RESULTS: The performance (mean steps ± SD) in the first and second test was 149 ± 34 and 149 ± 36 steps, respectively, which was correlated to distance (in meters) in 6MWT (r = 0.72; P < 0.05). Six-minute step test performance was reliable (ICC = 0.9; 95% confidence interval: 0.85-0.93). The equation to predict reference values for the first 6MST was significant (P < 0.001 and R = 0.48): Performance(steps) = 174 to 1.05 × Age(years) to women and Performance(steps) = 209 to 1.05 × Age(years) to men. CONCLUSIONS: Six-minute step test is a reliable and valid test. Moreover, the number of steps may be predicted by demographic and anthropometric variables with moderate strength of prediction. CLINICAL RELEVANCE: Six-minute step test is an exercise test that is easy to be conducted, more tolerable than a graded exercise test, requires fewer equipments and space, and permits better monitoring of the participants. The assessment of the reliability, validity, and reference values will provide a better interpretability for clinicians to use it, especially in primary care.

Oxygen Desaturation and Persistence of Symptoms During Activities of Daily Living in Patients Following Hospital Discharge for COVID-19.

BACKGROUND: COVID-19 can cause respiratory and multisystemic impairments, which lead to impaired activities of daily living (ADL). Telemonitoring after discharge from the hospital may help identify the persistence of such limitations during ADLs simulations. The aim of this study was to compare SpO2 , fatigue, and dyspnea through telemonitoring during a battery of 4 ADLs in patients following hospital discharge for COVID-19. METHODS: An observational cross-sectional study was conducted by using teleconferencing for patients 30 d after hospital discharge for COVID-19. The subjects were assessed and performed a simulated ADL battery (ie, walking, bathing and dressing, floor sweeping, and folding towels). SpO2 , fatigue, and dyspnea were monitored immediately after the end of each ADL; also, the subjects were asked to show the pulse oximeter on camera and grade their symptoms by using the Borg scale score (0-10). RESULTS: Sixty-six subjects were evaluated, all of whom were normoxic at rest. No significant difference in SpO2 was found among the ADLs. A portion of the subjects experienced desaturation on at least 1 ADL, which allowed subject grouping into the desaturated group, with highest portion of subjects who desaturated found during the walking task (18%), and the non-desaturated group. The subjects who desaturated were found to have more cardiovascular diseases (P = .031) and diabetes mellitus (P = .005) compared with those who did not desaturate. Both groups experienced mild symptoms; however, a percentage of the subjects with desaturation presented moderate-to-intense symptoms, with higher fatigue scores during walking, bathing and dressing, and floor sweeping. Increased dyspnea was also found during walking and during bathing and dressing in the subjects with desaturation. CONCLUSIONS: SpO2 was similar among the ADLs but walking triggered desaturation in a larger number of subjects. The subjects presented with mild-to-intense fatigue and dyspnea during ADLs 30 d after discharge after hospitalization for COVID-19 regardless of desaturation status, which demonstrated that the persistence of symptoms is independent of hypoxemia during exercise.

Effects of a cardiopulmonary telerehabilitation using functional exercises in individuals after COVID-19 hospital discharge: A randomized controlled trial.

INTRODUCTION: Individuals with severe coronavirus disease 2019 (COVID-19) may present respiratory and motor complications, requiring rehabilitation programs (RP) for long periods. However, access to cardiopulmonary rehabilitation is poor. Cardiopulmonary telerehabilitation is an alternative for cardiopulmonary dysfunction, improving functional capacity, dyspnea, and quality of life. Moreover, few clinical trials verified the effectiveness of telerehabilitation using functional exercise for post-COVID symptoms. Thus, the present study aimed to verify the effects of cardiopulmonary telerehabilitation using functional and accessible exercises in individuals after COVID-19 hospital discharge. METHODS: This blinded, randomized, and controlled clinical trial and included 67 adult individuals after COVID-19 hospital discharge. Participants were randomized into the groups of telerehabilitation (TG; n = 33) and control (CG; n = 34). TG underwent an individualized exercise program (functional and accessible exercises) supervised by a physical therapist (videoconference), and CG received guidance on general care and self-monitoring of vital signs (videoconference). The primary outcome was performance and physiological responses on the 6-minute step test (6MST). Secondary outcomes were performance on the 2-minute stationary walk test (2MSWT), 30-second chair stand test (30CST), and quality of life using the 36-Item Short Form Health Survey (SF-36) questionnaire physical functioning concept (PF). RESULTS: Functional capacity (6MST) improved by 28 ± 17 steps in TG and 15 ± 26 in CG (p = 0.04). For secondary outcomes, performance on 2MSWT increased by 39 ± 6 steps in TG and 10 ± 6 in CG (p = 0.00); 30CST by 3 ± 1 repetitions in TG and 1.5 ± 0.5 in CG (p = 0.05); and PF (SF-36) by 17 ± 4 points in TG and 12 ± 4 in CG (p = 0.00). Also, peak oxygen uptake VO2peak (6MST) improved by 3.8 ± 1 mL min-1 kg-1 in TG and 4.1 ± 1 in CG (p = 0.6), and heart rate demand (6MST) by 11 ± 37% in TG and -4 ± 19% in CG (p = 0.04). CONCLUSIONS: Cardiopulmonary telerehabilitation using functional exercises improved the exercise and functional capacity assessed using 6MST, 30CST, and 2MSWT and the quality of life of individuals after COVID-19 hospital discharge.

Should the 6-Minute Walk Test Be Compared When Conducted by 2 Different Assessors in Subjects With COPD?

BACKGROUND: The 6-min walk test (6MWT) is an important tool in the assessment of functional capacity and prognosis in patients with COPD. However, especially in long-term follow-up in clinical settings, this test may be executed by a different assessor, and it is not well known whether 6MWT has an acceptable inter-rater reliability. The aim of this study is to analyze the intra- and inter-rater reliability of the performance in 6MWT, its cardiorespiratory changes, and effort perception in subjects with COPD. METHODS: Thirty-two subjects with a diagnosis of COPD participated in the study, but 3 subjects did not appear on the second day of evaluation and therefore were included only in the intra-rater analysis; the first and second tests were executed by the same assessor with a 30-min interval between them, and the last was executed by a different assessor a week later. The intra-rater reliability was verified comparing the first and second 6MWT performance, and the inter-rater reliability was verified comparing the third test with the best performance of the first and second tests. RESULTS: The intraclass correlation coefficient values were >0.75 (P < .001) for the walked distance on the 6MWT; however, the limits of agreement, SE of measurement, and minimal detectable difference were higher than the minimum clinically important differences already mentioned in the literature (∼25, 26, and 54 m), and the coefficient of variation was small in both intra- and inter-rater comparisons. CONCLUSIONS: The 6MWT showed excellent reliability for distance and perceived exertion and moderate to excellent for HR and SD as assessed by intra- and inter-rater analysis. Thus, based on the main study outcomes, we concluded that the 6MWT can be compared when conducted by 2 different evaluators.

Reproducibility of cadence-free 6-minute step test in subjects with COPD.

BACKGROUND: Six-minute step test (6MST) has been used to assess functional capacity in chronic conditions; however, its reproducibility in the COPD population has not been evaluated. Our study objective was to evaluate 6MST reproducibility. METHODS: The test was performed in a single 20-cm height step, and subjects were instructed to step up and down (cadence-free) for 6 min. Subjects underwent three tests. The first and second were controlled by the same assessor with a 30-min interval. The third test was controlled by a different assessor one week later. For intra-rater comparison, the first and second performances of the test were used, and for inter-assessor comparison, the better performance of the first two tests was compared with the third test. RESULTS: Excellent intra-rater and inter-rater relative reproducibility was observed (intraclass correlation coefficient > 0.8), and there was no statistical difference (repeated measures of analysis of variance) among the performances of the three tests. Intra-rater error values were acceptable (mean error of 5.7 steps and limits of agreement between -7 and 18 steps). Inter-rater error values were not acceptable (mean error of 4.4 steps and limits of agreement between -20 and 29 steps. CONCLUSIONS: 6MST proved to be reproducible in the COPD population when performed by the same assessor.

Validity of the six-minute step test of free cadence in patients with chronic obstructive pulmonary disease.

OBJECTIVES: to evaluate the concurrent validity of the six-minute step test (6MST) in assessing exercise capacity of COPD patients using the six-minute walk test (6MWT) as a gold-standard. The predictive validity of the 6MST was assessed to determine a cut-off point for identification of low exercise capacity. METHOD: thirty-two COPD patients (50-87 years old) with mild to very severe obstruction performed the 6MST and 6MWT twice. RESULTS: Concurrent validity: a strong positive correlation (Pearson) between the number of ascents on the first (T1), second (T2) and the best of both (T1 or T2) tests during the 6MWT was observed. Although a moderate negative correlation with BODE index and FEV1 was found, it was considered insufficient to test the validity, therefore ROC curves were not applied. The predictive validity (ROC) of the 6MST to identify low physical capacity (compared with the 6MWT) using the performance of T1 or T2, or solely T1 was considered accurate, and the area under the curve was 0.8 (IC95% 0.62-0.98) and 0.85 (IC95% 0.70-0.99), respectively. To classify patients, the cut-off points of 86 and 78 steps were chosen, with both values showing 90% of sensitivity and specificity of 64% and 68% for T1 or T2, or solely T1, respectively. CONCLUSION: The number of steps on the 6MST was valid to verify exercise capacity in COPD patients and the cut-off point of 78 steps was able to identify patients with poor exercise tolerance. Values under this cut-off point are considered to identify patients with a poorer prognosis.

Determination of exacerbation predictors in patients with COPD in physical therapy - a longitudinal study.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) typically presents the characteristic clinical condition of exacerbation, with more intense symptoms associated with greater functional loss and consequently lower chances of patient survival. OBJECTIVES: This study sought to determine the predictors of exacerbation, alone or in combination, in patients with chronic obstructive pulmonary disease (COPD) who received physical therapeutic treatment over 6 months. METHOD: This was an observational, longitudinal and prospective study in which 63 COPD patients residing within the municipality of São Carlos, SP, Brazil were evaluated. These patients had COPD stages II and III and were entered into a physical therapy program, consisting of 3 periods of assessment over 6 months. We evaluated the occurrence of acute exacerbation as well as the patients' body mass index (BMI), fat-free mass (FFM), fat-free mass index, forced expiratory volume in 1 second (FEV1), dyspnea, distance walked (DW) in the 6-minute walk test (6MWT) and handgrip strength. RESULTS: When applying Cox settings with each covariate separately, the results revealed 5% significance only for the DW in the 6MWT, which demonstrated an interaction between BMI and FFM. Comparison of the 3 periods of assessment across the covariates measured showed a significant difference only for the DW between evaluations in the 3rd and 6th months. CONCLUSION: Upon analyzing the predictors of risk over 6 months of follow-up in patients with COPD, we found that the DW in the 6MWT was associated with the risk of exacerbation, although this risk also depended on the covariates BMI and FFM.

Determination of exacerbation predictors in patients with COPD in physical therapy - a longitudinal study / Determinação dos preditores de exacerbação nos pacientes com DPOC em tratamento fisioterapêutico - estudo longitudinal

Background: Chronic obstructive pulmonary disease (COPD) typically presents the characteristic clinical condition of exacerbation, with more intense symptoms associated with greater functional loss and consequently lower chances of patient survival. Objectives: This study sought to determine the predictors of exacerbation, alone or in combination, in patients with chronic obstructive pulmonary disease (COPD) who received physical therapeutic treatment over 6 months. Method: This was an observational, longitudinal and prospective study in which 63 COPD patients residing within the municipality of São Carlos, SP, Brazil were evaluated. These patients had COPD stages II and III and were entered into a physical therapy program, consisting of 3 periods of assessment over 6 months. We evaluated the occurrence of acute exacerbation as well as the patients' body mass index (BMI), fat-free mass (FFM), fat-free mass index, forced expiratory volume in 1 second (FEV1), dyspnea, distance walked (DW) in the 6-minute walk test (6MWT) and handgrip strength. Results: When applying Cox settings with each covariate separately, the results revealed 5% significance only for the DW in the 6MWT, which demonstrated an interaction between BMI and FFM. Comparison of the 3 periods of assessment across the covariates measured showed a significant difference only for the DW between evaluations in the 3rd and 6th months. Conclusion: Upon analyzing the predictors of risk over 6 months of follow-up in patients with COPD, we found that the DW in the 6MWT was associated with the risk of exacerbation, although this risk also depended on the covariates BMI and FFM. .

Contextualização: A doença pulmonar obstrutiva crônica (DPOC) normalmente cursa com condições clínicas características de exacerbação e, quanto maior o número delas, maior é a ocorrência de perda funcional e, consequentemente, menores são as chances de sobrevida dos pacientes. Objetivos: Determinar os preditores de exacerbação, isoladamente ou em interação, em pacientes com DPOC em tratamento fisioterapêutico ao longo de seis meses. Método : Trata-se de um estudo observacional, longitudinal e prospectivo, no qual foram avaliados 63 pacientes com DPOC estágios II e III, do município de São Carlos, SP, Brasil, inseridos em um programa fisioterapêutico, por meio de três períodos de avaliação ao longo de seis meses, quanto à ocorrência de exacerbação, bem como quanto ao índice de massa corpórea (IMC), massa magra (MM), índice de massa magra (IMM), volume expiratório forçado no primeiro segundo (VEF1), dispneia, distância percorrida (DP) no teste de caminhada de seis minutos (TC6) e força de preensão palmar. Resultados: Ao aplicar os ajustes de Cox com cada uma das covariáveis separadamente, observou-se significância de 5% apenas para a DP no TC6, a qual demonstrou interação com o IMC e também com a MM. Na comparação dos três períodos de avaliação quanto às covariáveis avaliadas, observou-se diferença significativa apenas para a DP entre as avaliações do 3º e 6º mês. Conclusão: Ao longo de seis meses de acompanhamento dos pacientes com DPOC quanto aos preditores de risco, pode-se observar que a DP no TC6 é um determinante no risco de exacerbação, no entanto depende das covariáveis IMC e MM. .

Validity of the six-minute step test of free cadence in patients with chronic obstructive pulmonary disease / Validade do teste de degrau de seis minutos de cadência livre em pacientes com doença pulmonar obstrutiva crônica

Objectives: to evaluate the concurrent validity of the six-minute step test (6MST) in assessing exercise capacity of COPD patients using the six-minute walk test (6MWT) as a gold-standard. The predictive validity of the 6MST was assessed to determine a cut-off point for identification of low exercise capacity. Method: thirty-two COPD patients (50-87 years old) with mild to very severe obstruction performed the 6MST and 6MWT twice. Results: Concurrent validity: a strong positive correlation (Pearson) between the number of ascents on the first (T1), second (T2) and the best of both (T1 or T2) tests during the 6MWT was observed. Although a moderate negative correlation with BODE index and FEV1 was found, it was considered insufficient to test the validity, therefore ROC curves were not applied. The predictive validity (ROC) of the 6MST to identify low physical capacity (compared with the 6MWT) using the performance of T1 or T2, or solely T1 was considered accurate, and the area under the curve was 0.8 (IC95% 0.62-0.98) and 0.85 (IC95% 0.70-0.99), respectively. To classify patients, the cut-off points of 86 and 78 steps were chosen, with both values showing 90% of sensitivity and specificity of 64% and 68% for T1 or T2, or solely T1, respectively. Conclusion: The number of steps on the 6MST was valid to verify exercise capacity in COPD patients and the cut-off point of 78 steps was able to identify patients with poor exercise tolerance. Values under this cut-off point are considered to identify patients with a poorer prognosis. .

Objetivos: Avaliar a validade concorrente do desempenho no teste de degrau de seis minutos (TD6) em analisar a capacidade física da DPOC, relacionando-o com o teste de caminhada de seis minutos (TC6), bem como verificar a presença de validade de critério preditiva do TD6, determinando um valor de corte para identificar baixa capacidade física. Método: Trinta e dois pacientes com DPOC estágios leve-muito grave, de ambos os sexos, entre 50-87 anos, realizaram dois TD6 e dois TC6. Resultados: Validade concorrente: observou-se correlação forte positiva (Pearson) entre o número de subidas do primeiro (T1), segundo (T2) e do melhor dos dois (T1 ou T2) TD6 com a distância percorrida no TC6. Embora constatamos correlações negativas entre os desempenhos no TD6 com o índice BODE e VEF1, essas não foram suficientes para caracterizar validade, não sendo traçadas as curvas ROC. A validade preditiva (curvas ROC) do TD6 para identificar baixa capacidade física (comparação com o TC6), utilizando o desempenho do T1 ou T2 ou somente do T1, foi considerada acurada para alguns propósitos, sendo a área abaixo da curva de 0,8 (IC95% 0,62-0,98) e 0,85 (IC95% 0,70-0,99), respectivamente. Para classificar os pacientes, escolhemos o ponto de corte de 86 e 78 degraus, apresentando sensibilidade de 90% e 90% e especificidade de 64% e 68%, para T1 ou T2 e somente T1, respectivamente. Conclusão: O desempenho no TD6 apresentou-se válido para verificar capacidade física na DPOC e identificou pacientes com baixa capacidade física, utilizando como ponto de corte 78 degraus, em que valores abaixo disso representaram pior prognóstico. .