Reliability, validity & responsiveness of the five-repetition sit-to-stand test in COPD

Background Limitations of space and learning effect prevent use of exercise tests in healthcare settings. The five-repetition Sit to Stand test (STS) measures the fastest time to stand and sit 5 times with arms folded. Normal values and reliability data for STS exist but there is a lack of data in COPD. Aim To show reliability of STS; the relationship between STS and incremental shuttle walk (ISW) and quadricep strength (QMVC); establish STS response to pulmonary rehabilitation (PR) and estimate minimum clinically important difference (MID) in COPD. Method Test-retest and inter-observer reliability were assessed in 80 and 50 COPD patients. STS, ISW, QMVC were measured in 475 patients. Relationships between STS, ISW, QMVC were assessed using Spearman rank correlation. STS, ISW and St George’s Respiratory Questionnaire (SGRQ) were measured pre/post an 8-week PR program. Anchor based methods (to those achieving known MID for ISW and SGRQ, and patient self-report) were used to estimate the MID. Results Test-retest and inter-observer reliability were excellent (ICC 0.99 and 1.00). STS correlated significantly with ISW (r=-0.59; p<0.001) and with QMVC (r=-0.38; p<0.001). STS improved significantly following PR (Pre: 14.1 (11.5, 21.3) vs Post: 12.4 (10.2, 16.3)secs; p<0.001) as did ISW and SGRQ (both p<0.001). Median changes in STS when anchored to ISW and SGRQ were -1.72 and -1.58 secs. Median change in STS in those feeling “better” or “much better” after PR was -1.49s. Conclusion The STS is reliable, correlates with ISW and QMVC and is responsive to PR in COPD patients. MID is between -1.5 and -2.0 secs. The STS may be a practical functional outcome tool suitable to use in most healthcare settings.