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.
['van den Houten|M M L|MM|', 'Gommans|L N M|LN|', 'van der Wees|P J|PJ|', 'Teijink|J A W|JA|']
D000368:Aged D005080:Exercise Test D005081:Exercise Therapy D005260:Female D005500:Follow-Up Studies D006801:Humans D007383:Intermittent Claudication D008297:Male D012189:Retrospective Studies D012720:Severity of Illness Index D011795:Surveys and Questionnaires D013997:Time Factors D016896:Treatment Outcome D016138:Walking
Intermittent claudication Supervised exercise therapy Peripheral arterial disease