Equação de predição do consumo máximo de oxigênio com aplicabilidade clínica para indivíduos pós-acidente vascular encefálico

Abstract

Individuals after stroke have low levels of cardiorespiratory fitness (CRF). For this reason, guidelines recommend that these individuals perform aerobic exercise. Therefore, this outcome must be systematically evaluated. The reference criterion for evaluating the CRF, cardiopulmonary exercise test (CPET), has limited clinical applicability. As an alternative, equations to predict maximal oxygen consumption (VO2max) have been used. As they have not yet been developed for individuals after stroke, using equations available in the literature can be an alternative. However, the validity of these equations to predict the VO2max of individuals after stroke has not yet been investigated. Therefore, this dissertation presented two objectives that were answered and presented in two different articles: article-1 and article-2. Article-1 aimed to investigate the validity of equations available in the literature to predict the VO2max of individuals after stroke. Article-2 aimed to develop an equation with clinical applicability and adequate validity to predict the VO2max of individuals after stroke. In both, individuals after chronic stroke able to walk independently were included. In article-1, four equations developed for sedentary individuals were selected considering the following criteria: variables possible to be obtained with individuals after stroke, having an equation for male and female individuals in the same study, performing the CPET on the treadmill to obtain the VO2max. To investigate validity, the agreement between measured and predicted VO2max was analyzed using the intraclass correlation coefficient (ICC) with a 95% confidence interval (95%CI) and the Bland-Altman method (α=5%). In article-2, multiple regressions were performed (step-1). Dependent variable: VO2max (ml.kg–1.min–1). Independent variables: age (years), sex (1-female; 2-male) and body mass index (BMI) (kg/m2) (considered in both analyses) and distance (meters) in the Six-Minute Walk Test (6MWT) (considered only in Equation-1) or in the Incremental Shuttle Walk Test (ISWT) (considered only in Equation-2). To investigate validity (step-2), the agreement between measured and predicted VO2max was analyzed using the ICC with 95%CI and the Bland-Altman method (α=5%). In article-1, 50 individuals (55±12 years; 67±74 months after stroke) were included. For the four equations, the 95%CI of the ICC included the zero value and the Bland-Altman method showed that they overestimated the VO2max (mean bias ranging from 1.92 to 9.24 ml.kg–1.min–1). In article-2, 50 individuals were included in stage-1 (55±12 years; 67±74 months after stroke) and 20 in stage-2 (58±8 years; 60±46 months after stroke). The four independent variables of each equation were retained (Equation-1: R²=0.68, p<0.001; Equation-2: R²=0.58, p<0.001). Equation-1: ICC=0.73 (95%CI=0.30 to 0.89; p=0.004), mean bias=0.003 ml.kg–1.min–1. Equation-2: ICC imprecise (95%CI=-0.12 to 0.82), since the 95%CI included the zero value, mean bias=0.971 ml.kg–1.min–1. In conclusion, the equations developed for sedentary individuals did not show adequate validity to predict the VO2max of individuals after stroke and, therefore, cannot be used with these individuals. Only Equation-1 developed in the present study (VO2max =22.239+0.020*distance in the 6MWT+4.039*sex-0.157*age-0.265*BMI) presented adequate validity to predict the VO2max of individuals after stroke and, therefore, should be used in the impossibility of performing the CPET.