Correspondence
Two Very Different Patient Populations
Any study addressing this issue must be seen as positive since valid studies on the subject are still missing even though patients have undergone short-term comprehensive cardiac rehabilitation for decades (1). With regard to the number of subjects and the length of the observation period, this study could have provided reliable data on mortality. However, the two patient populations—patients who underwent rehabilitation and patients who did not undergo rehabilitation—differed in variables known to influence the prognosis of coronary heart disease to such an extent that one could not expect the study to produce a credible result with regard to mortality. The markedly uneven distribution of risk factors and the obvious differences in coronary artery bypass graft surgery (CABG) and percutaneous coronary intervention (PCI) between the two groups indicate that two very different patient populations were evaluated. This issue cannot be resolved by multivariate analysis.
The discussion section conveys the impression that this study adds to the series of controlled studies all arriving at the conclusion that patients who underwent rehabilitation have a survival advantage. Although the three studies from Germany referred to in the article had a controlled design, they were randomized based on the intake of omega-3 fatty acids (OMEGA study) and the use of transtelephonic ECGs (registry study) or recruited from a registry (ACOS registry), but not randomized based on participation in cardiac rehabilitation. Therefore, rehabilitation was not evaluated in a controlled fashion.
Since in Germany health-insured persons are legally entitled to participate in rehabilitation, randomization for rehabilitation is not possible. However, comprehensive case-control studies are feasible from a scientific perspective. In the age of evidence-based medicine, the German statutory pension insurance scheme (Deutsche Rentenversicherung) or rather the linked German Society of Rehabilitation Science (DGRW, Deutsche Gesellschaft für Rehabilitationswissenschaften) is therefore called upon to present valid studies on the efficacy of rehabilitation. Unfortunately, the following statement still describes the present situation: “Scientific studies have not succeeded in demonstrating that rehabilitation increases the actual retirement age, lowers the need for nursing care and reduces morbidity and mortality“ (2).
DOI: 10.3238/arztebl.2016.0147a
Prof. Dr. med. Alfred Wirth
wirthbr@t-online.de
Conflict of interest statement
The author declares that no conflict of interest exists.
| 1. | Schlitt A, Wischmann P, Wienke A, Hoepfner F, Noack F, Silber RE, Werdan K: Rehabilitation in patients with coronary heart disease—participation and its effect on prognosis. Dtsch Arztebl Int 2015; 112: 527–34 VOLLTEXT |
| 2. | Wirth A, Klein G, Leptin H-J: Bessere Vernetzung notwendig. Dtsch Arztebl 2010; 25: A1253–6 VOLLTEXT |
