Stronger correlation of peak oxygen uptake with distance of incremental shuttle walk test than 6-min walk test in patients with COPD: a systematic review and meta-analysis

Abstract

Background: The 6-min walk test (6MWT) and incremental shuttle walk test (ISWT) are valid and reliable measures to assess exercise capacity of patients with chronic obstructive pulmonary disease (COPD). However, the comparison of correlation between peak oxygen uptake (peak VO2) and 6MWT or ISWT distance has not been investigated. We aimed to investigate the correlation between peak VO2 and 6MWT and ISWT distances in COPD patients through a meta-analysis. Methods: We systematically searched MEDLINE, Scopus, Embase, and the Cochrane Library up to June, 2020 for studies comparing the correlation of peak VO2 with either 6MWT or ISWT in COPD patients. Meta-analysis was performed with R software using a fxed-efect model. We compared the correlation coefcient and measured the heterogeneity using I2 statistics. Results: We identifed 12 studies involving 746 patients. Meta-analysis showed a signifcant correlation between peak VO2 and 6MWT and ISWT distances (6MWT: r=0.65, 95% CI 0.61–0.70; ISWT: r=0.81, 95% CI 0.74–0.85; p<0.0001). The heterogeneity was lower in ISWT than in 6MWT (6MWT: I2=56%, p=0.02; ISWT: I2=0%, p=0.71). Subgroup analysis showed a higher correlation coefcient in the low exercise capacity group than in the high exerci secapacity group in both feld tests. Conclusions: 6MWT and ISWT signifcantly correlated with peak VO2. Our fndings suggest that ISWT has a stronger correlation with peak VO2 than 6MWT. The exercise capacity in COPD patients may afect the strength of the relationship between peak VO2 and walking distance in both feld tests, suggesting the importance of using various exercise tests.