Valores de referência da distância percorrida para o shuttle teste modificado em crianças e adolescentes saudáveis no brasil: um estudo multicêntrico

Abstract

The Modified Shuttle Test (MST) is an alternative for evaluating the functional capacity of children and adolescents in relation to the gold standard test, the Cardiopulmonary Exercise Test. MST has advantages due to its practicality and lower application costs, making it possible to carry out it in places far from urban centers or with lower socioeconomic conditions. There are no reference values for the distance walked by healthy children and adolescents in the MST that consider the plurality of the Brazilian territory, only values from a single center. Reference values for the MST would help in the assessment of children and adolescents with some health condition, using the correct values for the distance walked expected for this population. This study aims to establish reference values for the distance walked in the MST in healthy children and adolescents aged 6 to 17 years in a multicenter sample that involved the five Brazilian regions. A cross-sectional, multicenter observational study was carried out in eight centers in the five regions of the country, in which 1319 Brazilian children and adolescents of both sexes underwent functional capacity assessment using the MST. Before applying the test, a screening questionnaire and pulmonary function test were administered, as well as height and body mass measurements. Two MST were performed at an interval of at least 30 minutes or until cardiorespiratory parameters returned to baseline. A third test was applied if the distance walked in the two tests varied by more than 40 meters. Sample size was calculated a posteriori based on the mean and standard deviation of the distance walked by the study subjects. An effect size of 0.45 was considered in a sample of 1004 subjects, with a sample power of 1.0 (100%). Descriptive statistical analysis was given by, mean and standard deviation. Differences between sexes were analyzed using the t test for independent samples. Furthermore, the value of the lower limit of normal (LLN) of the distance walked was stipulated for the different age groups and regions. Comparisons between age groups and regions of Brazil were carried out using one-way ANOVA and post hoc Tukey test. A significance level of 0.05 was considered. Thus, it was possible to establish reference values for the distance walked in the MST given through mean and standard deviation and by LLN. The average distance walked by the research subjects was 931 ± 260 m. Boys walked a greater distance in the MST compared to girls (995 ± 283 m versus 864 ± 214 m respectively, p < 0.0001). Boys had a higher average height than girls (147.3 cm ± 17 versus 143.9 ± 16 cm) (p < 0.001). There was a significant difference between the regions of Brazil in relation to the distance walked, where subjects from the northern region walked 937 ± 276 m (LLN = 898 m), northeast 835 ± 176 m (LLN = 809 m), central-west 851 ± 213 (LLN = 820 m), southeast 897 ± 230 (LLN = 877 m), south 1054 ± 219 m (LLN = 1028 m), p < 0.05. In relation to age, a significant difference was noticed between age groups, with a difference between the age groups of six years (649 ± 110 m) (LLN = 628 m); seven and eight years (770 ± 141 m) (LLN = 751 m); nine to 11 years (882 ± 176) (LLN 862 m), and 12 to 17 years (1036 ± 238 m) (LLN = 1015 m). This study established reference values for the distance walked in the MST in healthy children and adolescents aged 6 to 17 years in a multicenter sample representative of the five regions of Brazil, where the values were presented as mean, standard deviation and LLN of volunteers both by age and by Brazilian region. The volunteers presented a plateau in the distance walked when they reached adolescence and the southern region presented higher values of the distance walked in relation to the other regions. LLN values favor the identification of individuals with reduced functional capacity assessed by the MST.