Reliability and validity of six-minute step test in patients with heart failure

Validity and reliability of the 6-min stepper test in hypertensive individuals

BACKGROUND

Hypertension is a common public health problem characterized by high blood pressure (BP) and associated with complications such as coronary artery disease, stroke, and renal failure. Physical activity and exercise regulate BP, and assessment of exercise capacity is a cornerstone of exercise training.

OBJECTIVE

The aims of this study were to evaluate the validity and reliability of the 6-min stepper test (6MST) in hypertensive individuals and compare their physiological responses during the 6MST and 6-min walk test (6MWT).

METHODS

Forty individuals with hypertension were included. Participants performed the 6MWT and 6MST in separate morning and afternoon sessions. In each session, the test was repeated twice with a 30-min rest interval. Heart rate (HR), BP, perceived dyspnea, general fatigue, and leg fatigue were measured pre and posttest. Intraclass correlation coefficient (ICC), Bland-Altman plots, and standard error of measurement (SEM) were used to assess reliability. Pearson correlation analysis was used for convergent validity.

RESULTS

There was a strong and significant correlation between 6MWT distance and 6MST score ( r  = 0.689, P  < 0.001). Physiological responses during the 6MST had ICC values ranging from 0.70 to 0.89, suggesting good to excellent test-retest reliability. The SEM and minimum detectable difference (MDD) indicated the 6MST had low measurement error and high sensitivity.

CONCLUSION

The 6MST is a valid and reliable tool for assessing exercise capacity in people with HTN. Its practicality and ease of use make it a suitable alternative to the 6MWT for this population.

Effects of long-term Tai Chi vs. aerobic exercise on antioxidant activity and cognitive function in individuals with Parkinson's disease

An imbalance between the generation of reactive oxygen species and the body's antioxidant defense mechanisms is closely related to the development and progression of Parkinson's disease (PD). Considering that physical exercise is a potential therapeutic intervention for modulating oxidative stress markers and cognitive function in PD, the primary purpose of this study was to compare the effects of different long-term exercise modalities on antioxidants and cognitive performance in patients with PD. In addition, the secondary purpose was to explore whether changes in the levels of these biochemical markers are associated with alterations in cognitive performance pre- and post-intervention. In all, 61 participants were randomly divided into the aerobic exercise (AE, n=20), Tai Chi exercise (TCE, n=21), or control (n=20) group. Blood samples were collected before and after a 12-week intervention period for the analysis of antioxidant markers [leukocyte 8-hydroxydeoxyguanosine (8-OHdG), catalase (CAT), glutathione (GSH), glutathione peroxidase (GSH-Px), oxidized glutathione (GSSG), superoxide dismutase (SOD), and uric acid (UA)]. Cognitive function was evaluated using the Mini-Mental State Examination (MMSE). Although no significant changes were observed in the activity of 8-OhdG, GSH-Px, GSSG, GSH:GSSG ratio, SOD, and cognitive performance in the AE and TCE groups, the 12-week AE intervention led to a significant increase in CAT and GSH levels, along with a significantly decrease in UA levels among individuals with PD. Conversely, the TCE intervention resulted in a significant increase in GSH levels. However, SOD activity and MMSE scores were significantly decreased after 12 weeks in the control group. The correlations between changes in MMSE scores and changes in the levels of GSH and UA prior to and after the intervention reached significance in the AE group. Thus, long-term AE and TCE might serve as effective strategies for reducing oxidative damage and preserving cognitive function in PD, with AE exhibiting greater benefits compared with TCE. These findings hold potential clinical relevance as complementary measures to standard medical treatments and alternative therapies, such as antioxidant supplements and dietary adjustments, particularly for individuals in the early stages of PD.

Heart failure associated with chronic Chagas cardiomyopathy increases the risk of impaired lung function and reduced submaximal functional capacity

BACKGROUND

With the evolution of chronic Chagas cardiomyopathy (CC) and the progression towards heart failure (HF), patients may show a decline in inspiratory muscle strength, lung function, and functional capacity.

OBJECTIVE

We compared respiratory function and submaximal functional capacity in patients with CC with versus without HF.

METHODS

This observational, cross-sectional study was carried out with CC patients divided into CCG, a group without HF (n = 28), and HFG, a group with HF (n = 27). Spirometry (percent predicted forced vital capacity (ppFVC), forced expiratory volume in one second of FVC (ppFEV1), forced expiratory flow between 25 % and 75 % of FVC (ppFEF25-75%), and maximum voluntary ventilation (ppMVV)) and submaximal functional capacity (six-minute step test: 6MST) were evaluated. Mann-Whitney (comparison of pulmonary function and functional capacity between groups) and linear regression (association between the presence of HF and other variables) were performed.

RESULTS

We included 55 participants, with median age of 67 years (56.25-71.75) and 54.55 % males. Dyslipidemia was the most recurrent comorbidity (49.09 %). HFG presented lower ppFVC (P = 0.000), ppFEV1 (P = 0.011), ppFEF25-75% (P = 0.017), and ppMVV (P = 0.003) than the CCG. The ppFVC (B = -18.95; P = 0.000), ppFEV1 (B = -16.29; P = 0.021), ppFEF25-75% (B = -19.57; P = 0.014), ppMVV (B = -16.59; P = 0.003), and 6MST (B = -17.13; P = 0.034) were negatively associated with the presence of HF.

CONCLUSION

Our data suggest that impaired lung function, compatible with a restrictive pulmonary pattern, is present among adults with CC and HF.

Prognostic value of the duke activity Status Index Questionnaire in predicting mortality in patients with chronic heart failure: 36-month follow-up study

BACKGROUND

The Duke Activity Status Index (DASI) questionnaire has been the focus of numerous investigations - its discriminative and prognostic capacity has been continuously explored, supporting its use in the clinical setting, specifically during rehabilitation in patients with chronic heart failure (CHF).However, studies exploring optimal DASI questionnaire threshold scores are limited.

OBJECTIVE

To investigate optimal DASI questionnaire thresholds values in predicting mortality in a CHF cohort and assess mortality rates based on the DASI questionnaire using a thresholds values obtained.

METHODOLOGY

This is a prospective cohort study with a 36-month follow-up in patients with CHF. All patients completed a clinical assessment, followed by DASI questionnaire, pulmonary function, and echocardiography. The Receiver Operating Characteristic (ROC) curve analysis was used to discriminate the DASI questionnaire score in determining the risk of mortality. For survival analysis, the Kaplan-Meier model was used to explore the impact of ≤/>23 points on mortality occurring during the 36-month follow-up.

RESULTS

One hundred and twenty-four patients were included, the majority being elderly men. Kaplan Meier analysis revealed that ≤/> 23 was a strong predictor of CHF mortality over a 36-month follow-up.

CONCLUSION

A score of ≤/>23 presents good discriminatory capacity to predict mortality risk in 36 months in patients with CHF, especially in those with reduced or mildly reduced ejection fraction. Age, ejection fraction, DASI questionnaire score and use of digoxin are risk factors that influence mortality in this population.

Type 2 diabetes mellitus negatively affects the functional performance of 6-min step test in chronic heart failure: a 3-year follow-up study

BACKGROUND

Type 2 diabetes mellitus (T2DM) and chronic heart failure (CHF) present a decrease in functional capacity due to the intrinsic nature of both pathologies. It is not known about the potential impact of T2DM on functional capacity when assessed by 6-min step test (6MST) and its effect as a prognostic marker for fatal and non-fatal events in patients with CHF.

OBJECTIVE

to evaluate the coexistence of T2DM and CHF in functional capacity through 6MST when compared to CHF non-T2DM, as well as to investigate the different cardiovascular responses to 6MST and the risk of mortality, decompensation of CHF and acute myocardial infarction (AMI) over 36 months.

METHODS

This is a prospective cohort study with 36 months of follow-up in individuals with T2DM and CHF. All participants completed a clinical assessment, followed by pulmonary function testing, echocardiography, and 6MST. The 6MST was performed on a 20 cm high step and cardiovascular responses were collected: heart rate, systemic blood pressure, oxygen saturation, BORG dyspnea and fatigue. The risk of mortality, acute myocardial infarction and decompensation of CHF was evaluated.

RESULTS

Eighty-six participants were included. The CHF-T2DM group had a significantly lower functional capacity than the CHF non-T2DM group (p < 0.05). Forced Expiratory Volume in one second (L), ejection fraction (%), gender and T2DM influence and are predictors of functional capacity (p < 0.05; adjusted R squared: 0.419). CHF-T2DM group presented a higher risk of mortality and acute myocardial infarction over the 36 months of follow-up (p < 0.05), but not to the risk of decompensation (p > 0.05).

CONCLUSION

T2DM negatively affects the functional performance of 6MST in patients with CHF. Gender, ejection fraction (%), FEV1 (L) and T2DM itself negatively influence exercise performance.

Feasibility of a Novel Augmented 6-Minute Incremental Step Test: A Simplified Cardiorespiratory Fitness Assessment Tool

Background

The cardiopulmonary exercise test (CPET) is considered a gold standard in assessing cardiorespiratory fitness (CRF) but has limited accessibility due to competency requirements and cost. Incorporating portable sensor devices into a simple bedside test of CRF could improve diagnostic and prognostic value.

Objectives

The authors sought to evaluate the association of an augmented 6-minute incremental step test (6MIST) with standard CPET.

Methods

We enrolled patients undergoing clinically indicated supine cycle ergometry CPET with invasive hemodynamics (iCPET) for the same-day 6MIST. CRF-related variables were simultaneously recorded using a signal morphology-based impedance cardiograph (PhysioFlow Enduro) and a portable metabolic analyzer (VO2 Master Pro) during incremental pace stationary stepping. The correlation between CPET and hemodynamic parameters from both tests was assessed using the intraclass correlation coefficient (ICC).

Results

Fifteen patients (mean age 60 ± 14 years, 40% female, 27% Black) were included. All patients who agreed to undergo 6MIST completed the study without any test-related adverse events. We observed good to excellent correlation between iCPET- and 6MIST-measured CPET parameters: peak heart rate (ICC = 0.60; 95% CI: 0.15-0.85), absolute peak O2 consumption (VO2) (ICC = 0.77; 95% CI: 0.44-0.92), relative peak VO2 (ICC = 0.64; 95% CI: 0.20-0.86), maximum ventilation (ICC = 0.59; 95% CI: 0.13-0.84), O2 pulse (ICC = 0.71; 95% CI: 0.33-0.89), and cardiorespiratory optimal point (ICC = 0.82; 95% CI: 0.52-0.94). No significant correlation was determined between iCPET and 6MIST in measuring cardiac index at rest (ICC = 0.19; 95% CI: -0.34 to 0.63) or at peak exercise (ICC = 0.36; 95% CI: -0.17 to 0.73).

Conclusions

We demonstrate the feasibility of a novel augmented 6MIST with wearable devices for simultaneous CPET and hemodynamic assessment. 6MIST-measured CPET parameters were strongly correlated with the iCPET-derived measurements. Additional studies are needed to confirm the validity of the 6MIST compared to standard upright CPET.

The six-minute step test can predict COPD exacerbations: a 36-month follow-up study

The six-minute step test (6MST) has been shown to be effective in assessing exercise capacity in individuals with COPD regardless of severity and, despite its easy execution, accessibility and validity, information on the prognostic power of this test remains uncertain. The aim of this study is to investigate whether the 6MST can predict the occurrence of exacerbations in patients with COPD. This is a prospective cohort study with a 36-month follow-up in patients with COPD. All patients completed a clinical assessment, followed by pulmonary function testing and a 6MST. The 6MST was performed on a 20 cm high step; heart rate, blood pressure, oxygen saturation, BORG dyspnea and fatigue were collected. Sixty-four patients were included in the study, the majority being elderly men. Performance on the 6MST demonstrated lower performance compared to normative values proposed in the literature, indicating a reduced functional capacity. Kaplan Meier analysis revealed that ≤ 59 steps climbed during the 6MST was a strong predictor of COPD exacerbation over a 36-month follow-up. We have identified a minimal threshold number of steps (≤ 59) obtained through the 6MST may be able predict the risk of exacerbations in patients with COPD.

Submaximal Field Walking Tests Applied in the Cardiopulmonary Assessment in Congenital Heart Diseases: A Systematic Review

INTRODUCTION

Submaximal field walking tests are easy to apply and low cost, but it is necessary to standardize their application, especially in the pediatric population. The feasibility and its use in patients with congenital heart disease have been studied. The goal of this study was to verify which are the submaximal field walking tests applied in the cardiopulmonary assessment of children and adolescents with CHD and to verify if they are being performed as recommended by the standardization protocols/guidelines.

METHODS

Literature review through a search in six electronic databases, structured in PICO format, without date restrictions. Looking for studies that used submaximal field walking tests in children and adolescents with congenital heart disease aged 5 to 18 years. Methodological quality, effectiveness and safety and risk of bias were assessed.

RESULTS

Five studies met the eligibility criteria with a sample of 160 individuals with congenital heart disease, and all used the six-minute walk test. Note that different methodologies and modifications are used. Only the clinical trial showed good methodological quality.Four studies had low risk of bias and one study had moderate risk.

CONCLUSION

Although the six-minute walk test is the only test used as a field test found in our research, there is no standardization in the application of the test, making it difficult to compare the results. In this sense, reducing the limitations and heterogeneity in the application of the test will enable more concrete outcomes and facilitate their reproduction in clinical practice.

Normative values and reference equation for the six-minute step test to evaluate functional exercise capacity: a multicenter study

Objective: To establish normative values and a reference equation for the number of steps climbed during the six-minute step test (6MST) in healthy adults, and to assess the reliability of the test and of the equation. Methods: This was a multicenter cross-sectional study involving 468 healthy volunteers (age range: 18-79 years) recruited from the general community in six research laboratories across different regions of Brazil, which is a country with continental dimensions. The 6MST was performed twice (30-min interval), and clinical, demographic, and functional variables were evaluated. An independent sample of 24 volunteers was evaluated to test the reference equation a posteriori. Results: The number of steps had excellent test-retest reliability (intraclass correlation coefficient = 0.96 [95%CI: 0.95-0.97]), and the mean number of steps was 175 ± 45, the number being 14% greater in males than in females. The best performance on the test was correlated with age (r = -0.60), sex (r = 0.28), weight (r = 0.13), height (r = 0.41), BMI (r = -0.22), waist circumference (r = -0.22), thigh circumference (r = 0.15), FVC (r = 0.54), and physical activity level (r = 0.17; p < 0.05 for all). In the regression analysis, age, sex, height, and weight explained 42% of the variability of the 6MST. Normative values were established for the 6MST according to age and sex. There was no difference between the 6MST values from the independent sample and its predicted values (157 ± 29 steps vs. 161 ± 25 steps; p = 0.47; 97% of predicted values). Conclusions: The normative values and the reference equation for the 6MST in this study seem adequate to accurately predict the physical functional performance in adults in Brazil.