Article Text
Abstract
Aims To investigate the relationship between exercise participation, exercise ‘dose’ expressed as metabolic equivalent (MET) hours (h) per week, and prognosis in individuals attending an extended, community-based exercise rehabilitation programme.
Methods Cohort study of 435 participants undertaking exercise-based cardiac rehabilitation (CR) in Leeds, West Yorkshire, UK between 1994 and 2006, followed up to 1 November 2013. MET intensity of supervised exercise was estimated utilising serial submaximal exercise test results and corresponding exercise prescriptions. Programme participation was routinely monitored. Cox regression analysis including time-varying and propensity score adjustment was applied to identify predictors of long-term, all-cause mortality across exercise dose and programme duration groups.
Results There were 133 events (31%) during a median follow-up of 14 years (range, 1.2 to 18.9 years). The significant univariate association between exercise dose and all-cause mortality was attenuated following multivariable adjustment for other predictors, including duration in the programme. Longer-term adherence to supervised exercise training (>36 months) was associated with a 33% lower mortality risk (multivariate-adjusted HR: 0.67; 95% CI: 0.47 to 0.97; p=0.033) compared with all lesser durations of CR (3, 12, 36 months), even after adjustment for baseline fitness, comorbidities and survivor bias.
Conclusion Exercise dose (MET-h per week) appears less important than long-term adherence to supervised exercise for the reduction of long-term mortality risk. Extended, supervised CR programmes within the community may play a key role in promoting long-term exercise maintenance and other secondary prevention therapies for survival benefit.
- survival
- submaximal exercise testing
- fitness
- exercise volume
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Footnotes
Contributors CTa (corresponding author), CT, KW, SC, LI contributed to the study design. CTa, SC, CT, JM, JWM and MD collected the data. CTa, LI, SC involved in editing and data preparation. CTa performed the data analysis. CTa, SC and LI contributed to the first draft of the manuscript. CT, SC, LI, read and critically appraised several versions of the manuscript. All authors have critically revised the manuscript for important intellectual content and provided final approval of the version for publication.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Ethics approval Approval for this study was granted in 2013 from Yorkshire and the Humber (Leeds East) Local Research Ethics Committee (reference 13/YH/0099) and the Health Research Authority Confidentiality Advisory Group (reference CAG 5-03(PR6)/2013).
Provenance and peer review Not commissioned; externally peer reviewed.