How to Demonstrate the Impact of Cardiac Rehabilitation on Cardio-renal Protection.

To the Editor I have read with great interest the article of Kitajima and colleagues, who investigated the impact of long-term cardiac rehabilitation on cardio-renal protection in elderly patients with cardiovascular diseases (1). I have two concerns that would likely improve the implications of their findings.

First, despite their statement on “long-term cardiac rehabilitation”, few patients [6/44 (14%)] completed 5 years of follow-up. A five-year complete cohort set with appropriate statistical comparisons would strengthen the implications of their findings. A repeat analysis of variance among those who completed 5 years of follow-up would be appropriate for a trend analysis.

Second, to strengthen their finding that cardiac rehabilitation maintained the cardio-renal function, any efforts to prepare a control group are suggested. Patients with a similar background may have comparable outcomes, irrespective of cardiac rehabilitation. A randomized control trial would ideal, and a background-matched cohort without cardiac rehabilitation or a pre-cardiac rehabilitation cohort (i.e., pre vs. post comparison) would be an alternative control group.

The author states that he has no Conflict of Interest (COI).