Short- and long-term reliability of the 1-minute sit-to-stand test in patients with COPD.

<bold>Background:</bold> The 1-min sit-to-stand test (1STST) is a valid exercise test to assess the functional exercise capacity of COPD patients, yet its reliability characteristics have not been comprehensively investigated in COPD. <bold>Objectives:</bold> The aim of this study was to evaluate the short- (the same day) and long-term (one month apart) test-retest reliability of the 1STST in a large cohort of stable COPD patients as well as in COPD subgroups. <bold>Methods:</bold> Patients with COPD performed two consecutive 1STST at baseline, followed by two additional 1STST during a second visit one month later. The number of 1STST repetitions, cardiorespiratory parameters and dyspnea were measured at each test occasion. Short-term (within-visit) and long-term (between-visit) reliability measurements were calculated in the entire cohort as well as in subgroups defined according to the severity of dyspnea (mMRC grades <2 vs ≥2) or the severity of airflow obstruction (GOLD ≤2 vs ≥3). <bold>Results:</bold> 118 patients were analyzed. The within-visit (same day) reliability, as expressed by intraclass correlation coefficients (ICC) was excellent for 1STST repetitions (≥0.95) and good to excellent for related changes in cardiorespiratory parameters and dyspnea (≥0.83). There was a significant but clinically not relevant difference in two 1STST interspersed by 1 month of −0.3 ± 0.8 repetitions (p<0.001). The between-visit reliability was excellent, ICC: 0.93 (95%CI: 0.90; 0.95). Within-visit and between-visit reliability characteristics of 1STST outcomes remained consistent in the different COPD subgroups. <bold>Conclusions:</bold> The 1STST shows excellent short- and long-term reliability in COPD patients regardless of the severity of the disease.