Fig. 4From: 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-analysisLinear regression test of funnel plot asymmetry for identifying publication bias. Abbreviations: 6MWT, 6-min walk test; peak VO2, peak oxygen uptake; ISWT, incremental shuttle walk testBack to article page