Minimal clinically important differences in treadmill, 6-minute walk, and patient-based outcomes following supervised and home-based exercise in peripheral artery disease

Abstract

We estimated minimal clinically important differences (MCIDs) for small, moderate, and large changes in measures obtained from a standardized treadmill test, a 6-minute walk test, and patient-based outcomes following supervised and home-based exercise programs in symptomatic patients with peripheral artery disease (PAD). Patients were randomized to either 12 weeks of a supervised exercise program (n=60), a home-based exercise program (n=60), or an attention-control group (n=60). Using the distribution-based method to determine MCIDs, the MCIDs for small, moderate, and large changes in peak walking time (PWT) in the supervised exercise group were 38, 95, and 152 seconds, respectively, and the changes in claudication onset time (COT) were 35, 87, and 138 seconds. Similar MCID scores were noted for the home-based exercise group. An anchor-based method to determine MCIDs yielded similar patterns of small, moderate, and large change scores in PWT and COT, but values were 1–2 minutes longer than the distribution approach. In conclusion, 3 months of supervised and home-based exercise programs for symptomatic patients with PAD results in distribution-based MCID small, moderate, and large changes ranging from 0.5 and 2.5 minutes for PWT and COT. An anchor-based approach yields higher MCID values, ranging from a minimum of 73 seconds for COT to a maximum of 4 minutes for PWT. The clinical implication is that a goal for eliciting MCIDs in symptomatic PAD patients through a walking exercise intervention is to increase PWT and COT by up to 4 minutes, which corresponds to two work stages during the standardized progressive treadmill test.