Discussion
PROM, low back pain, Pain
While the previously reported primary endpoint results in the SUNFIT trial (6MWT) did not differ between treatment strategies [At three months, a significant difference was observed, in favor of both SEP and HSEP versus WA, in the VascuQoL Emotional domain as well as in the overall Summary score. In the VascuQoL Summary score, this significant difference in favor of SEP versus WA also remained at six months. Additionally at six months, a significant difference was observed in the VascuQoL Pain domain, in favor of SEP as compared with the other offered treatment strategies. While the observed effect sizes were generally small to moderate, these exploratory findings might still be related to important treatment differentials that were not evident when assessed by objective walking tests such as maximal- and pain-free walking distance as reported in the primary analysis of the SUNFIT trial [At three and six months, we observed significant between-group results regarding some VascuQoL domain and summary items favoring SEP and HSEP as compared with WA. In addition to the exercise performed in SEP and HSEP, the potential benefits of the exercise encouragement, support and feedback given by the physiotherapists [A significantly higher proportion of patients in the SEP group (compared with HSEP and WA) reached the VascuQoL summary score MID for improvement at the one-year follow-up visit. The MID thresholds calculated by Conjin et al. [Moreover, it is important to consider the context in which these thresholds were derived. Compared with our one-year result, Conjin and colleagues had a shorter follow-up period of three to four months. Also, the IC treatment offered differed in the studied population and included SEP, percutaneous transluminal angioplasty (PTA), and surgical revascularization while some patients only received best medical treatment (antiplatelet drug and a statin, unsupervised walk advice and advice on lifestyle changes). However, the MID values can be applied irrespective of sample size and are thus useful in both individual care and research settings [The fact that the SF36 is a generic PROM that provides a wider HRQoL measure than PAOD-specific PROMs [To the best of our knowledge, this is the first study evaluating exercise programs with the PSFS in patients with IC. The impact of exercise has previously been evaluated with the PSFS in patients with low back pain [There are many different questionnaires evaluating HRQoL in patients with IC and the use of these tools in a research context is inconsistent and non-standardized [