What service and patient characteristics are associated with cardiac rehabilitation outcomes: Evaluation of observational studies of cardiac rehabilitation as a complex intervention

Cardiac rehabilitation (CR) is proven to benefit patients post cardiac event, however, modern CR varies in terms of service quality, patient characteristics and outcomes. The aim was to investigate the variations and their association with patient outcomes. Five observational studies make up this thesis. The studies have some unique and shared aims and methodology leading to distinct findings summarised through a synthesis chapter showcasing the incremental nature of the analyses and progression in researcher ability. Observational methodology was justified, and variation in routine care and the association with three distinct categories of outcome: psychosocial wellbeing, physical fitness and cardiovascular risk factors. Study one concluded that volume, as a service factor, appeared not to be associated with patient outcomes whereas multiple patient factors such as age and gender were found to be associated. Study two, building upon the findings of the first, focused on the patient characteristics including employment status and showed that, aligning with wider literature, patient psychosocial wellbeing was poorer pre and post CR in patients who were unemployed. This association of employment and psychosocial wellbeing was replicated in Study three which was the first to also assess the influence of mode of delivery. Mode was found to be not significantly associated with psychosocial wellbeing or functional capacity in Study four. In Study five, mode was categorised as supervised or facilitated self-managed and found no association with patient outcomes, this time risk factors. The use of routine data highlights important insights for answering research questions to inform and promote service change. Additionally, the findings may influence the methodological approach and expectations by researchers utilising the National Audit of Cardiac Rehabilitation. The conclusions of this thesis will help to inform CR delivery, directly impacting patients and clinicians. The findings may help to shape the future services designed by policy makers.