Poor cardiorespiratory fitness ups risk of mortality

An inverse, independent, and graded association exists between cardiorespiratory fitness (CRF) and mortality risk across the spectra of age, sex, and race, a recent study has found. In addition, there is no risk increase seen among extremely fit individuals.

This study examined a total of 750,302 US veterans aged 30‒95 years (mean age 61.3 years), including 110,637 septuagenarians, 26,989 octogenarians, 142,798 African Americans, 35,197 Hispanics, 16,050 Native Americans, and 45,232 women.

The authors objectively established age- and sex-specific CRF categories (quintiles and 98th percentile) based on peak metabolic equivalent (MET) achieved during a standardized exercise treadmill test. They also estimated hazard ratios (HRs) with 95 percent confidence intervals (CIs) for mortality across the CRF categories using multivariable Cox models.

Of the participants, 174,807 died (mean 22.4 events per 1,000 person-years) during a median follow-up of 10.2 years. The adjusted association between CRF and mortality risk was inverse and graded across the spectra of age, sex, and race.

Mortality risk was lowest at approximately 14.0 METs for men (HR, 0.24, 95 percent CI, 0.23‒0.25) and women (HR, 0.23, 95 percent CI, 0.17‒0.29), with no evidence of risk increase with extremely high CRF. On the other hand, mortality risk was four times higher among the least fit (HR, 4.09, 95 percent CI, 3.90‒4.20) compared with extremely fit individuals.

“Being unfit carried a greater risk than any of the cardiac risk factors examined,” the authors said.