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An Equation With Clinical Applicability and Adequate Validity to Predict the Maximum Oxygen Consumption of
Paula da Cruz Peniche1, Larissa Tavares Aguiar2, Maria Teresa Ferreira Dos Reis1
1Department of Physical Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Objective:
To develop an equation with clinical applicability and adequate validity to predict the maximum oxygen consumption (V̇o2max) of individuals post-stroke.
Design:
A cross-sectional study.
Setting:
A university laboratory.
Participants:
Individuals post-stroke in the chronic phase (at least 6 months post-stroke). Step-1 (equation development): n=50, aged 55±12 years; Step-2 (validity investigation): n=20, aged 58±8 years (N=50 [step 1], N=20 [step 2]).
Interventions:
Not applicable.
Main Outcome Measure(S):
Step-1 (equation development): multiple linear regression analysis was performed.
Dependent Variable:
V̇o2max (mL/kg/min) in the cardiopulmonary exercise test.
Independent Variables:
age (years), sex (1-women, 2-men), body mass index (BMI) (kg/m2), and distance (meters) in the Six-Minute Walk Test (6MWT) (6MWT-Equation) or in the Incremental Shuttle Walk Test (ISWT) (ISWT-Equation). Step-2 (validity investigation): agreement between the V̇o2max measured and predicted was evaluated with the intraclass correlation coefficient (ICC) with 95% confidence interval (CI) and the Bland-Altman method (α=5%).
Results:
In step-1 (equation development), the 4 independent variables for each equation were retained (6MWT-Equation: R2=0.68, P<.001; ISWT-Equation: R2=0.58, P<.001). In step-2 (validity investigation), the 6MWT-Equation showed an ICC of 0.73 (95% CI=0.30, 0.89; P=.004) and a mean bias of 0.003 mL/kg/min; and the ISWT-Equation showed an imprecise ICC of 0.55 (95% CI=-0.12, 0.82; P=.045) and a mean bias of 0.971 mL/kg/min. 6MWT-Equation (V̇o2max=22.239+0.02 × distance in the 6MWT+4.039 × sex-0.157 × age-0.265 × BMI) showed adequate validity.
Conclusions:
An equation with clinical applicability and adequate validity in the investigated sample was developed to predict the V̇o2max of individuals post-stroke in the chronic phase (6MWT-Equation). Future studies with larger sample should investigate its external validity.