Cut-off of the one-minute sit-to-stand test to detect functional impairment in people with chronic obstructive pulmonary disease

INTRODUCTION: The 6-minute walking test (6MWT) is a widely used measure to assess functional status of people with chronic obstructive pulmonary disease (COPD). However, it requires a long hallway and might be time-consuming. Other simple measures might be useful as a first screening tool. We explored the predictive ability of the 1-minute sit-to-stand test (1-min STS) in discriminating people with COPD with or without functional impairment.

METHODS: A receiver operating characteristics (ROC) curve analysis was performed. We determined a threshold for the 1-min STS to identify functional impairment based on different cut-offs of the 6MWT (300, 350, 400 and 450 m).

RESULTS: A total of 135 people with COPD were included. Except for the <450 m cut-off of the 6MWT, all other cut-offs identified 19.5 repetitions as the optimal cut-off point for the 1-min STS. All AUCs showed excellent discrimination (AUCs = 0.812-0.901). The best AUC (<300 m cut-off) had an outstanding discrimination (0.901; 95%CI: 0.84-0.96; other AUCs 0.812-0.836) between people with or without functional impairment, with 86% specificity and 83% sensitivity.

CONCLUSION: A cut-off of 19.5 repetitions in the 1-min STS discriminates accurately people with COPD with a functional impairment. Future studies may validate our treatable trait candidate in other samples and investigate its utility in predicting other meaningful outcomes.