Is estimated cardiorespiratory fitness an effective predictor for cardiovascular and all-cause mortality? A meta-analysis.

BACKGROUND AND AIMS: Estimated cardiorespiratory fitness (eCRF) derived from algorithm correlates well with exercise testing-measured CRF, yet its clinical use for mortality risk stratification has not been systematically evaluated. This meta-analysis with dose-response analysis was conducted to quantify its association with risk of cardiovascular and all-cause mortality. METHODS: Electronic databases were searched for prospective cohort studies that investigated the association of eCRF with risk of cardiovascular and all-cause mortality. Study-specific multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) per 1-metabolic equivalent (MET) higher of eCRF were pooled using a random-effects model. RESULTS: Twenty-five datasets from 8 cohort studies that enrolled more than 170,000 participants were included. The summary HR per 1-MET higher of eCRF was 0.83 (95% CI 0.80 to 0.86) for cardiovascular mortality (11 datasets) and 0.83 (95% CI 0.78 to 0.88) for all-cause mortality (14 datasets) in the general population. These associations showed no sex-difference and were all linearly shaped (all p nonlinearity ≥ 0.27). The performance of eCRF (assessed by the area under the curve) in discriminating future risk of cardiovascular and all-cause mortality was higher than all its components (such as physical activity, resting heart rate, and body mass index, all p < 0.05), but slightly lower than exercise testing-measured CRF. CONCLUSIONS: Higher eCRF was independently associated with lower risk of cardiovascular and all-cause mortality in the general population, indicating that eCRF might hold the potential as an effective and practical risk prediction tool in epidemiological or population research.