Avaliação da mobilidade funcional por meio do Timed Up & Go (TUG) em indivíduos idosos com DPOC: o uso do protocolo em velocidade usual ou máxima interfere em sua interpretação?

Abstract

Introduction: The Timed Up & Go (TUG) test assesses functional mobility and has gained relevance in Chronic Obstructive Pulmonary Disease (COPD), primarily affecting elderly individuals. In this population, the TUG has been suggested for fall risk screening and as a measure of physical performance related to nutritional assessment. It can also be used in different physical performance assessment scenarios, in addition to demonstrating consistent measurement properties. The original protocol requires individuals to walk at their usual speed, but over the years, another protocol at maximum speed has been suggested. Due to the relatively subtle difference in test execution, many researchers have used both variations in individuals with COPD, sometimes treating them as interchangeable, which can be problematic. Objective: To compare the time in the usual TUG with the time in the maximum TUG, and to verify if the time in the maximum TUG is able to predict the time in the usual TUG in elderly individuals with COPD. Methods: A cross-sectional study that included clinically stable individuals diagnosed with COPD, aged 60 years or older, and without conditions that could compromise or confound the results of the assessment. An initial assessment was performed to obtain sociodemographic (e.g., sex, age), anthropometric (e.g., weight, height), and clinical (pulmonary function, impact of dyspnea, health status) data. Functional mobility was assessed using two TUG protocols: TUG_usual and TUG_max (the test consists of asking the individual to walk a pre-established 3- meter path, starting and returning to a seated position, and timing the time required to complete it; in TUG_usual, the usual speed was requested, while in TUG_max, the maximum speed was requested). Results: One hundred and eighty elderly individuals with COPD were included, with a mean age of 72 (67-77) years, mostly female (56%), and a mean post-bronchodilator 1-second expiratory volume of 56 ± 19% of predicted. The median time in the usual TUG was 12.0 (10.49- 14.53) seconds, statistically greater than in the maximum TUG of 9.31 (7.91-11.11) seconds (p<0.0001), with a difference between the two tests of 2.74 (1.83-3.85) seconds. One hundred and nine (61%) individuals presented reduced functional mobility in the usual TUG and 91 (51%) in the maximum TUG. There was a discrepancy in classification between the two protocols in 36 individuals (20% of the sample). Both protocols showed a reasonable correlation with the age variable, in addition to showing a weak or no correlation with the mMRC variable (p<0.0001). A regression analysis indicated that the TUG_usual time can only be predicted for men, based on the TUG_max time and age using the following equation: TUG_usual time = -0.806 + (1.027 x TUG_max time) + (0.047 x age); R2 = 0.85, p<0.001. Conclusion: The TUG_usual time is statistically greater than the TUG_max time in elderly patients with COPD. Furthermore, approximately 20% of the sample differed in the classification of reduced functional mobility between the protocols, suggesting that the protocols are not interchangeable. However, for men, the TUG_usual time can be acceptably predicted from the TUG_max time and age.