Clinical trials versus the real world: the example of cardiac rehabilitation

Clinical practice should follow evidence-based medicine, which is derived from clinical trials. The outcomes of clinical practice, however, may not equal that of trials if there are differences in the patients or the quality of treatment they receive. We report the example of cardiac rehabilitation to illustrate this point, comparing the characteristics of patients and treatments offered in randomised controlled trials (RCTs) in this area with those included in two large surveys of cardiac rehabilitation in the UK. We found that cardiac rehabilitation as currently practised in the UK is unlikely to be as effective as clinical trials may suggest.