Percentage of Age-Predicted Cardiorespiratory Fitness and Risk of Incident Hypertension: A Prospective Cohort Study

Purpose: There are inverse and independent associations between cardiorespiratory fitness (CRF) and several adverse cardiometabolic outcomes including hypertension (HT). The prospective relationship between percentage of age-predicted CRF (%age-predicted CRF) and risk of HT has not been previously investigated. We aimed to assess the association of %age-predicted CRF with incident HT in a long-term prospective cohort study.
Methods: Cardiorespiratory fitness, as measured by peak oxygen uptake, was assessed using the gold standard respiratory gas exchange analyser in 1,602 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to %age-predicted CRF using (achieved CRF/age-predicted CRF)*100. Hazard ratios (HRs) (95% confidence intervals, CIs) were estimated for HT.
Results: During a median follow-up of 26.8 years, 308 HT cases were recorded. There was a linear relationship between age-predicted CRF and incident HT (p-value for non-linearity=.68). A 1 standard deviation increase in %age-predicted CRF was associated with a decreased risk of HT in analysis adjusted for established risk factors (HR 0.79; 95% CI 0.69–0.90), which remained consistent on further adjustment for several other potential confounders including alcohol consumption, physical activity, socioeconomic status and inflammation (HR 0.83; 95% CI 0.72–0.95). The corresponding adjusted HRs (95% CIs) were 0.55 (0.38-0.80) and 0.63 (0.43-0.91) respectively, when comparing extreme quartiles of %age-predicted CRF levels. The HRs for the association of absolute CRF levels with HT risk in the same participants were similar.
Conclusions: Percentage of age-predicted CRF is linearly, inversely and independently associated with risk of incident HT and it is comparable to absolute CRF as a risk indicator for HT in a general population of middle-aged men.