Abstract
BACKGROUND: Supervised exercise is an integral part of the recommended first-line treatment for patients with intermittent claudication (IC). By reflecting the patients' perspectives, patient-reported outcome measurements provide additional knowledge to the biomedical endpoints and are important outcomes to include when evaluating exercise interventions in patients with IC. We aimed to evaluate the one-year impact of three strategies: unsupervised Nordic pole walk advice (WA), WA + six months of home-based structured exercise (HSEP) or WA + six months of hospital-based supervised exercise (SEP) on health-related quality of life and patient-reported physical function in patients with IC. METHODS: This secondary exploratory analysis of a multi-center, randomized clinical trial compared three exercise strategies. The primary outcome of the secondary analysis was the one-year change in the 36-Item Short-Form (SF-36). Secondary outcomes were three- and six-months SF-36 changes alongside three, six- and 12-months changes in the disease-specific Vascular Quality of Life instrument (VascuQoL) and the Patient-Specific Functional Scale (PSFS). The Kruskal-Wallis test with Bonferroni-adjusted post-hoc tests were used for between-group comparisons. Effect size calculations were used to describe the size of observed treatment effects, and the clinical meaningfulness of observed changes in the VascuQoL summary score at one year was studied using established minimally important difference (MID) thresholds. RESULTS: A total of 166 patients with IC, mean age: 72.1 (SD 7.4) years, 41% women, were randomized. No significant between-group differences were observed over time for the SF-36 or the PSFS scores whereas some significant between-group differences were observed in the VascuQoL domain and summary scores over time, favoring SEP and/or HSEP over WA. The observed SF-36 and VascuQoL domain and summary score effect sizes were small to moderate, and many domain score effect sizes also remained unchanged over time. A significantly higher proportion of the patients in the SEP group reached the VascuQoL summary score MID of improvement in one year. CONCLUSION: Clinically important improvements were observed in SEP using the VascuQoL, while we did not observe any significant between-group differences using the SF-36. Whereas effect sizes for the observed changes over time were generally small, a significantly higher proportion of patients in SEP reached the VascuQoL MID of improvement. TRIAL REGISTRATION: NCT02341716, January 19, 2015 (retrospectively registered).