To What Extent Is Service Variation in Cardiac Rehabilitation Associated with Exercise Capacity and Physical Activity Outcomes

Abstract

Aim: This thesis examines how variations in cardiac rehabilitation (CR) service delivery and patient characteristics are associated with exercise capacity (EC) and physical activity (PA) outcomes, with particular attention to post-COVID-19 practice. Methods: A literature review was conducted to identify and critically appraise studies examining associations between CR delivery characteristics (mode of delivery, CR duration, number of sessions) and EC or PA outcomes. Searches across electronic databases and reference lists yielded 24 eligible studies, which informed variable selection from the National Audit of Cardiac Rehabilitation (NACR). Routine NACR data was utilised in two observational studies. EC was assessed using the Incremental Shuttle Walk Test (ISWT) and the 6-Minute Walk Test (6MWT), and PA was based on recommended activity levels. Multivariable logistic regression examined associations between service-level factors, patient-level characteristics and the likelihood of achieving minimum clinically important difference (MCID) thresholds for EC and meeting PA recommendations. Results: Group-based CR programmes were more likely to achieve the MCID for EC and met the PA recommendation. Furthermore, participants attending CR after the COVID-19 pandemic were less likely to achieve the MCID for EC but more likely to meet PA recommendations. In terms of CR duration, longer programmes were positively associated with meeting PA recommendations, showed no association with ISWT MCID, and were negatively associated with 6MWT MCID. Older, female, obesity, comorbidity, current smoking and lower baseline PA were generally associated with poorer EC and PA outcomes. Conclusion: This thesis established that variation in the CR mode of delivery is associated with poorer EC and PA outcomes. Patient-level characteristics such as older age, female and greater comorbidity were all associated with poorer outcomes. Modifiable factors notably, obesity and smokers, were associated with poorer outcomes. An awareness of these characteristics could inform future tailoring of CR delivery and optimise patient benefit.