Minimally Important Difference of the Absolute and Functional Claudication Distance in Patients with Intermittent Claudication.

OBJECTIVE: Disease severity and treatment outcomes in patients with intermittent claudication (IC) are commonly assessed using walking distance measured with a standardized treadmill test. It is unclear what improvement or deterioration in walking distance constitutes a meaningful, clinically relevant, change from the patients' perspective. The purpose of the present study was to estimate the minimally important difference (MID) for the absolute claudication distance (ACD) and functional claudication distance (FCD) in patients with IC. METHOD: The MIDs were estimated using an anchor based approach with a previously defined clinical anchor derived from scores of the walking impairment questionnaire (WIQ) in a similar IC population. Baseline and 3 month follow up data on WIQ scores and walking distances (ACD and FCD) were used from 202 patients receiving supervised exercise therapy from the 2010 EXITPAD randomized controlled trial. The external WIQ anchor was used to form three distinct categories: patients with "clinically relevant improvement," "clinically relevant deterioration," and "no clinically relevant change." The MIDs for improvement and deterioration were defined by the upper and lower limits of the 95% confidence interval of the mean change in ACD and FCD, for the group of IC patients that remained unchanged according to the WIQ anchor. RESULTS: For the estimation of the MID of the ACD and FCD, 102 and 101 patients were included, respectively. The MID for the ACD was 305 m for improvement, and 147 m for deterioration. The MID for the FCD was 250 m for improvement, and 120 m for deterioration. CONCLUSION: The MIDs for the treadmill measured ACD and FCD can be used to interpret the clinical relevance of changes in walking distances after supervised exercise therapy and may be used in both research and individual care.

Editor's choice--The effect of supervision on walking distance in patients with intermittent claudication: a meta-analysis.

BACKGROUND: A number of reviews have reported the influence of exercise therapy (ET) for the treatment of intermittent claudication (IC). However, a complete overview of different types of ET is lacking. The aim of this meta-analysis was to study the effect of supervision on walking capacity in patients with IC. It was hypothesized that there was a positive treatment effect in relation to the intensity of supervision and improvement in walking capacity (i.e., a "dose-response" hypothesis). METHODS: A systematic search in the Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE databases was performed. Only randomized controlled trials (RCTs) evaluating the efficacy of an ET in IC were included. Type of supervision, treadmill protocol, length of ET, total training volume, and change in walking distance were extracted. RCTs were categorised according to type of support: no exercise, walking advice, home-based exercise (HB-ET), and supervised exercise therapy (SET). A standardised mean difference between pre- and post-training maximal walking distance (MWD) and pain-free walking distance (PFWD) was calculated for all subgroups at 6 weeks, and 3 and 6 months of follow up. RESULTS: Thirty studies involving 1406 patients with IC were included. The overall quality was moderate-to-good, although number of included patients varied widely (20-304). The intensity of supervision was directly related to MWD and PFWD. SET was superior to other conservative treatment regimens with respect to improvement in walking distances at all follow-ups. However, the difference between HB-ET and SET at 6 months of follow up was not significant. CONCLUSION: Supervised exercise therapy for intermittent claudication is superior to all other forms of exercise therapy. Intensity of supervision is related to improved walking distance.