Sit-to-stand test in children with bronchiectasis: Does it measure functional exercise capacity?

Background: Similar to six-minute walk test (6MWT), sit-to-stand test (STST) is a self-paced test which elicits sub-maximal effort; therefore, it is suggested as an alternative measurement for functional exercise capacity in various pulmonary conditions including COPD and cystic fibrosis. We aimed to investigate the association between 30-second STST (30s-STST) and 6MWT in both children with bronchiectasis (BE) and their healthy counterparts, as well as exploring cardiorespiratory burden and discriminative properties of both tests. Methods: Sixty children (6 to 18-year-old) diagnosed with non-cystic fibrosis BE and 20 age-matched healthy controls were included. Both groups performed 30s-STST and 6MWT. Test results, and heart rate, SpO(2) and dyspnea responses to tests were recorded. Results: Univariate analysis revealed that 30s-STST was able to explain 52% of variance in 6MWT (r = 0.718, p<0.001) in BE group, whereas 20% of variance in healthy controls (r = 0.453, p = 0.045). 6MWT elicited higher changes in heart rate and dyspnea level compared to 30s-STST, indicating it was more physically demanding. Both 30s-STST (21.65 +/- 5.28 vs 26.55 +/- 3.56 repetitions) and 6MWT (538 +/- 85 vs 596 +/- 54 m) were significantly lower in BE group compared to healthy controls (p<0.01). Receiver operating characteristic (ROC) curve analysis revealed an area under the ROC curve (UAC) of 0.765 for 30s-STST and 0.693 for 6MWT in identifying the individuals with or without BE (p<0.05). Comparison between AUCs of 30s-STST and 6MWT yielded no significant difference (p = 0.466), indicating both tests had similar discriminative properties. Conclusions: 30s-STST is found to be a valid alternative measurement for functional exercise capacity in chil-dren with BE. (c) 2020 Elsevier Inc. All rights reserved.