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Utility of exercise capacity as HF surrogate endpoint mixed
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For HF interventions, exercise capacity was a poor surrogate endpoint for mortality and hospitalization, but may be valid as a surrogate for health-related quality of life, researchers reported.
The researchers conducted a systematic review of 31 randomized controlled trials of exercise-based cardiac rehabilitation vs. no exercise control in 4,784 patients with HF. They pooled outcomes using random-effects meta-analyses and estimated the effects of cardiac rehabilitation on exercise capacity, mortality, hospitalization and health-related quality of life.
Compared with controls, exercise-based cardiac rehabilitation was associated with positive effects on exercise capacity as determined by peak VO2 (3.1 mL/kg/min; 95% CI, 2.01-4.2) and 6-minute walk test (41.15 m; 95% CI, 16.68-65.53), Oriana Ciani, PhD, from the Institute of Health Research, University of Exeter Medical School, United Kingdom, and the Centre for Research on Health and Social Care Management, Bocconi University, Milan, and colleagues wrote.
There was a low level of association between improvement in exercise capacity and better rates of mortality (Peters test P = .162) and hospitalization (Peters test P = .373), according to the researchers.
Ciani and colleagues determined there was a moderate level of correlation between improvement in exercise capacity and better health-related quality of life (Egger test P = .078).
To predict a significant improvement in health-related quality of life due to improvement in exercise capacity, the surrogate threshold effect was 5 mL/kg/min for peak VO2 and 80 m for 6-minute walk test, according to the researchers.
“Our study findings have significant implications for future HF trials,” Ciani and colleagues wrote. “Contrary to epidemiological (observational) evidence, our results show that intervention effects on [exercise capacity] are not predictive of treatment effects on the clinical events of mortality or hospitalization. However, we also showed that improvements in [exercise capacity], if large enough, can be predictive of important gains in patient [health-related quality of life].”
In a related editorial, David J. Whellan, MD, MHS, from Sidney Kimmel Medical College, Thomas Jefferson University, wrote that the study “confirms the ability of peak VO2 and [6-minute walk test] distance to provide important information regarding how patients will feel with a new treatment. Having a validated surrogate for quality of life will help in the identification of new treatments for patients with heart failure.” – by Erik Swain
Disclosures: The authors and Whellan report no relevant financial disclosures.
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