Physical activity and exercise in patients with intermittent claudication

Sammanfattning: Introduction. Supervised exercise is a guideline recommendation in patients with intermittent claudication (IC). As the availability of supervised exercise varies, interest has turned to the more accessible home-based exercise programmes. However, the reported effects of home-based exercise programmes are inconsistent and there are knowledge gaps in terms of studies evaluating effectiveness of both supervised and home-based exercise programmes over longer time periods as compared to unsupervised walk advice (WA) alone. There is also a need to evaluate health-related quality of life (HRQoL) and daily physical activity during an exercise intervention. Walk tests are important for the objective assessment of walking ability, but the measurement properties of the 6-minute walk test have scarcely been studied in IC. The overall aim of this thesis was to evaluate the effectiveness of unsupervised WA alone or in combination with a hospital-based supervised exercise programme (SEP) or a home-based structured exercise programme (HSEP) on walking ability, muscle endurance, HRQoL, self-reported physical function and daily physical activity and to study the test-retest reliability and agreement of the 6-minute walk test in patients with IC. Methods. Papers I-III originate from the SUNFIT trial (Supervised or UNsupervised exercise training For Intermittent claudication), a three-armed, multi-centre, randomised clinical trial including patients with IC. Papers I-III aimed to evaluate the effectiveness of an SEP, HSEP and WA on: I) walking ability and muscle endurance, II) generic (Short-Form 36 (SF-36) and disease-specific (Vascular Quality of life Questionnaire (VascuQoL) HRQoL and self-reported physical function and III) daily physical activity assessed with an accelerometer. Paper IV was a reliability and agreement study of the first 100 patients who enrolled the SUNFIT trial at Sahlgrenska University Hospital and performed the 6-minute walk test twice at baseline. Main results. A total of 166 patients with IC (mean age: 72.1 (SD 7.4) years, 41% women) were included in Papers I-III. Paper I confirmed that an HSEP was non-inferior to an SEP, but that none of these interventions was significantly better than WA alone. In Paper II, no significant between-group differences were observed over time in generic HRQoL, while significant between-group differences were observed in disease-specific HRQoL in for example: at one-year in the domain Social (non-significant post hoc tests) and at six months in Summary score (favour SEP vs. WA) and in the domain Pain (favour SEP vs. both HSEP and WA). A significantly higher proportion of patients in the SEP reached the minimally important difference threshold for improvement in the VascuQoL Summary score at one year. Paper III showed no significant between-group differences at one year in any of the outcomes of accelerometer-measured physical activity. Paper IV demonstrated that the 6-minute walk test has excellent test-retest reliability, with a minimal detectable change at 46 m. Conclusions. An HSEP was shown to be non-inferior to an SEP, but no significant differences were observed at one year between an HSEP, SEP and WA, in terms of the 6-minute walk test maximum and pain-free walking distance, muscle endurance or daily physical activity. In the VascuQoL, a few of the domains and Summary score reached a significant between-group differences over time and a significantly higher proportion of patients in the SEP reached the minimally important difference threshold for improvement in the VascuQoL Summary score at one year. This study is limited by low exercise adherence to the HSEP and SEP. As such, there is a need for future studies to assess the optimal exercise intervention to improve outcomes in this population. The 6-minute walk test has excellent test-retest reliability in patients with IC and can be recommended for use in clinical patient evaluation and as an important endpoint in clinical trials.