Changes in Cardiorespiratory Fitness and Survival in Patients With or Without Cardiovascular Disease.
Level 3 - non-randomized controlled study
Observational longitudinal cohort study with repeated measures.
PubMed 36948729 · doi:10.1016/j.jacc.2023.01.027
What was done
Longitudinal cohort study of 93,060 participants aged 30–95 years (mean 61.3 ± 9.8 years) who completed two symptom-limited exercise treadmill tests at least 1 year apart (mean 5.8 ± 3.7 years). Participants were categorized into baseline age-specific cardiorespiratory fitness (CRF) quartiles using peak METs and stratified by subsequent CRF trajectory (increase, decrease, or no change). Multivariable Cox proportional hazards models estimated hazard ratios (HRs) and 95% CIs for all-cause mortality over a median follow-up of 6.3 years (IQR: 3.7–9.9 years).
What was found
During follow-up, 18,302 participants died (average yearly mortality rate: 27.6 per 1,000 person-years). CRF changes ≥1.0 MET showed inverse, proportionate changes in mortality risk across baseline fitness levels. A CRF decline of >2.0 METs was associated with higher mortality risk in low-fit individuals with cardiovascular disease (HR: 1.74; 95% CI: 1.59–1.91) and without cardiovascular disease (HR: 1.69; 95% CI: 1.45–1.96).
Why it matters
This study shows that cardiorespiratory fitness is a dynamic, modifiable risk factor, where changes as small as 1 MET track with meaningful shifts in long-term survival regardless of baseline fitness.
Limits
The observational design cannot establish causality, and fitness declines may be driven by subclinical disease progression (reverse causation). The abstract has an internal contradiction regarding whether participants had no baseline cardiovascular disease or were stratified by CVD status. Specific causes of death, behavioral confounders, and clinical indications for repeat exercise testing were not reported.
Cited by
- supports Research by Jonathan Myers and the Cooper Clinic shows that individuals who improve their fitness over time gain a survival advantage equivalent to those who maintained high fitness, whereas those who lose fitness lose that advantage.