Outpatient cardiac rehabilitation part IV: Options für a prospective study

After the completion of the retrospective cohort study in June 2010 the Association of Austrian Health Insurance Providers (HVB) suggested, that the LBI-HTA should prepare options for a prospective study to assess the effectiveness of phase III cardiac rehabilitation. We discussed e.g. study aims and the organisational framework of a study in numerous meetings with representatives of HVB, pension and health insurance and AGAKAR. We did sample size calculation for all potential primary endpoints based on data from the previous retrospective study and literature. As a result we suggested a prospective, non-randomised controlled observational study with two parallel groups (with/ without phase III rehabilitation). Power calculations revealed that most of the potential endpoints would require unrealistic improvement under given circumstances (observation time, maximum of patients that could be recruited/ treated in phase III) to achieve statistical significance. Therefore we focussed on patients with “unfavourable risk profile” at the end of phase II, because larger effects can be expected (and asked for). Only patients who have not reached at least 3 of 5 rehabilitation targets of the defined risk categories (body weight, blood lipids, blood glucose, blood pressure, smoking status) at the end of phase II will be included. Primary endpoint will be the change of the total 9 single targets of the 5 risk categories previously used for patient inclusion. A total of 450 patients will be included (200 intervention group, 250 control group). Study results could be used to define the indication for phase III for patients at higher cardiovascular risk and as decision-aid for the prolongation of contracts. Based on the presented study concept HVB and other potential study sponsors can appraise if the expected benefit of the study (statistical assessment of “reaching the rehabilitation targets”, descriptive report of changes of other outcome parameters) is in a favourable relation to the required resources.