Associations between estimated cardiorespiratory fitness and mortality risk in stroke survivors: a population-based...

Although cardiorespiratory fitness (CRF) has been linked to a lower risk of incident stroke, its prognostic value in stroke survivors remains unclear. We therefore aimed to examine whether the estimated CRF (eCRF) could predict long-term outcomes in stroke survivors.

This study included 1,306 stroke survivors (mean age 65.64 years; 43.75% men) from the 1999-2018 National Health and Nutrition Examination Survey. We calculated the eCRF using a previously validated non-exercise algorithm based on age, sex, body mass index, waist circumference, resting heart rate, physical activity, and smoking status. The associations between eCRF and all-cause and cardiovascular disease (CVD) mortality were assessed using Cox proportional hazards regression models to report hazard ratios (HRs) and 95% confidence intervals (CIs).

During a median follow-up of 78 months, 566 (43.34%) participants died, including 225 (17.23%) from CVD. Compared to the lowest tertile, the multivariate-adjusted HRs (95% CIs) for the middle and highest tertile of eCRF were 0.74 (0.57-0.97) and 0.52 (0.38-0.73), respectively, for all-cause mortality, and 0.71 (0.45-1.12) and 0.41 (0.24-0.70), respectively, for CVD mortality. Restricted cubic spline curves demonstrated a nonlinear relationship between eCRF and both all-cause and CVD mortality, with inflection points at eCRF values of 6.13 METs and 6.15 METs, respectively. Subgroup analysis showed that the association between eCRF and CVD mortality was more pronounced in women.

In US stroke survivors, eCRF is non-linearly associated with both all-cause and CVD mortality. Therefore, eCRF may serve as a simple and convenient parameter for assessing long-term outcomes in this population.