Clinically Meaningful Change in 6 Minute Walking Test and the Incremental Shuttle Walking Test following Coronary Artery Bypass Graft Surgery

Abstract

The 6-min walk test (6MWT) and incremental shuttle walk test (ISWT) are widely used measures of exercise tolerance, which depict favorable performance characteristics in a variety of cardiac and pulmonary conditions. Both tests are valid and reliable method of assessing functional ability in cardiac rehabilitation population. Several studies have calculated the minimal clinically important difference (MCID) of these exercise tests in different populations. The current study aims to estimate MCID of 6MWT and ISWT in patients after Coronary artery bypass graft (CABG) surgery. In this descriptive observational study, nonprobability purposive sampling technique was used to assess 89 post CABG patients. The participants performed the 6MWT and ISWT along with vital monitoring on third, fifth and seventh post operative days. The data was with calculation of 6MWT and ISWT MCID through distribution and anchor-based methods. Results showed significant improvement (p < 0.001) in 6MWT as well as in ISWT after seven days of in-patient cardiac rehabilitation. The minimal detectable difference of 6MWT determined by the distribution-based method was 36.11 whereas MCID calculated by Anchor based method was 195 m. The minimal detectable difference of ISWT determined by the distribution-based method was 9.94 whereas MCID calculated by Anchor based method was 42.5 m. In conclusion our results will assist the future researchers and clinicians to interpret clinical trials as well as to observe the clinical course of post operative cardiac patients.