Validation of the two-minute step test in obese with comorbibities and morbidly obese patients

Abstract

Cardiopulmonary fitness assessment is a valuable resource to obtain quantitative indicators of an individual's physical performance. The cardiopulmonary exercise test (CPX), considered the gold standard test for this evaluation, is costly and difficult to be accessed by the general population. In order to make this evaluation more accessible, and to better reflect the performance of daily life activities, alternative tests were proposed. Morbidly obese patients present limitations that impair physical performance assessment and could benefit from a test of shorter duration, provided it is validated. This observational study aimed to validate the two-minute step test (2MST) as a tool to evaluate functional capacity (FC) in obese with comorbidities and morbidly obese patients, compared the 2MST with CPX as a measure of physical performance, and developed a predictive equation to estimate peak oxygen uptake (VO 2 ) in the 2MST. The CPX and the 2MST were performed and metabolic and ventilatory parameters were recorded in 31 obese individuals (BMI>35 kg/m 2 ). Pearson correlation and multiple linear regression analyses were performed to evaluate the peak VO 2 best predictors. Bland-Altman analysis was performed to assess the agreement between the two methods. Peak VO 2 measured by CPX and 2MST showed a strong correlation (r=0.70, P<0.001) and there was a moderate correlation between peak VO 2 of the 2MST and the number of up-and-down step cycles (UDS) (r=0.55; P=0.01). The reference equation obtained was: VO 2 (mL·kg -1 ·min -1 ) = 13.341 + 0.138 × total UDS – (0.183 × BMI), with an estimated standard error of 1.3 mL·kg -1 ·min -1 . The 2MST is a viable, practical, and easily accessible test for FC. UDS and BMI can predict peak VO 2 satisfactorily.

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

“…A significant proportion of patients interrupted the test due to lower limb fatigue. These results were observed previously in other chronic disease populations (32)(33)(34).…”

“…Another important finding of our study was that the CPET workload was strongly associated with the 6MST number of steps, allowing the prescription of exercises on a cycle-ergometer for this population based on number of steps achieved (Table 4) (32)(33)(34).…”

“…However, peak blood pressure and RER were higher during the CPET than the 6MST (22). Therefore, the CPET workload induces cardiovascular responses in this population that might present more risks during an exercise assessment (32)(33)(34).…”

Reporting Standards for a Bland–Altman Agreement Analysis: A Review of Methodological Reviews

“…• the unbowed popularity of BA plots, as judged by the number of citations of the seminal papers [1,3] (and a pedagogical update [4]); • the limited extent to which BA plots are reported and interpreted in the literature (e.g., [15][16][17]40]); and • the associated need for standardization, as evidently expressed by the included proposals [13,22,23,[30][31][32][33].…”

“…The latter extended their work by offering a freely-available online implementation, accompanied by a formal description of the more advanced Bland-Altman comparison methods [14], and they proposed a standard format of reporting a BA agreement analysis. However, recent examples of Bland-Altman plots employing samples as small as 31 [15], 6 and 12 [16], or 14 [17] can be found easily in MEDLINE/PubMed (by searching for "Bland-Altman" and "Agreement" and limiting the search to publication dates in August 2019). These studies did not quantify the uncertainty of the estimated BA LoA by means of confidence intervals.…”