Cardiorespiratory fitness changes in patients receiving comprehensive outpatient cardiac rehabilitation in the UK: a multicentre study

Abstract

Background Exercise training is a key component of cardiac rehabilitation but there is a discrepancy between the high volume of exercise prescribed in trials comprising the evidence base and the lower volume prescribed to UK patients. Objective To quantify prescribed exercise volume and changes in cardiorespiratory fitness in UK cardiac rehabilitation patients. Methods We accessed n=950 patients who completed cardiac rehabilitation at four UK centres and extracted clinical data and details of cardiorespiratory fitness testing pre-and post-rehabilitation. We calculated mean and effect size (d) for change in fitness at each centre and converted values to metabolic equivalent (METs). We calculated a fixed-effects estimate of change in fitness expressed as METs and d. Results Patients completed 6 to 16 (median 8) supervised exercise sessions. Effect sizes for changes in fitness were d=0.34-0.99 in test-specific raw units and d=0.34-0.96 expressed as METs. The pooled fixed effect estimate for change in fitness was 0.52 METs (95% CI 0.51 to 0.53); or an effect size of d=0.59 (95% CI 0.58 to 0.60). Conclusion Gains in fitness varied by centre and fitness assessment protocol but the overall increase in fitness (0.52 METs) was only a third the mean estimate reported in a recent systematic review (1.55 METs). The starkest difference in clinical practice in the UK centres we sampled and the trials which comprise the evidencebase for cardiac rehabilitation was the small volume of exercise completed by UK patients. The exercise training volume prescribed was also only a third that reported in most international studies. If representative of UK services, these low training volumes and small increases in cardiorespiratory fitness may partially explain the reported inefficacy of UK cardiac rehabilitation to reduce patient mortality and morbidity.

Submaximal fitness and mortality risk reduction in coronary heart disease: a retrospective cohort study of community-based exercise rehabilitation

“…However, since neither relationship was expressed in the context of survival benefit per MET increment in exercise capacity, it is not possible to quantify the change in fitness comparable with international studies. The overall improvement in sCRF within our cohort (0.82 MET) is analogous to that estimated during maximal testing by Barons et al (1.08 METs) and congruent with the ∼0.5 MET improvement estimated by Sandercock et al 8 in 950 patients undergoing submaximal testing across four UK CR centres.…”

“… 10 A previous international meta-analysis has suggested mean CRF improvements of 1.6 METs following CR, though it did not include data from the UK. 11 In contrast, the estimated mean MET change determined from submaximal testing during supervised exercise training across four UK centres was 0.5 MET; 8 though the exercise prescription in these centres was conservative by European standards. 12 Thus, whether this magnitude of CRF change is representative of typical UK CR is not known.…”

“…Studies examining mortality and CRF outcomes from UK CR programmes are sparse. 8 9 The largest randomised clinical trial of CR in the UK reported no survival benefit from CR, though importantly, it did not consider changes in patients' CRF levels. 10 A previous international meta-analysis has suggested mean CRF improvements of 1.6 METs following CR, though it did not include data from the UK.…”

Exercise training characteristics in cardiac rehabilitation programmes: a cross-sectional survey of Australian practice

“…While Australian programmes currently meet the majority of exercise recommendations prescribed in their own nominal guidelines, it is also pertinent to examine further whether the ‘real-life provision’ of exercise training in Australian CR, like that in the UK, fails to meet the levels observed in RCTs and recommended in international clinical guidelines. 48 49 …”

CARE CR-Cardiovascular and cardiorespiratory Adaptations to Routine Exercise-based Cardiac Rehabilitation: a study protocol for a community-based controlled study with criterion methods

“…This may lead to inaccurate reporting of VO 2peak changes following CR in patients with CHD. 28 There is a need to investigate the exercise-based CR findings of Sandercock et al 29 using ‘gold-standard’ CPET testing methods.…”