Although a strong proponent of cardiac rehabilitation services, I must take exception to the recent article by Lavie and Milani1 who attempted to identify predictors of lipid value changes in cardiac rehabilitation participants. In my opinion, numerous methodologic problems in their study invalidate most of their conclusions.
First of all, the lack of a control group prevents forming any conclusions about the effect of cardiac rehabilitation participation itself on lipid value changes. Despite the fact that the authors acknowledged this weakness in their study, still their main conclusion was that "our results strongly support the beneficial effects of cardiac rehabilitation and exercise training on plasma lipid values, indexes of obesity, and exercise capacity."1 Without a control group with which to compare, such a statement is at best an overstatement. Improvements in exercise capacity have been documented in both intervention and control group patients in other studies of cardiac