Predicting 10-year mortality in older adults using VO₂max, oxygen uptake efficiency slope and frailty class.

Maximal oxygen uptake (VO2max) is the gold-standard cardiorespiratory fitness (CRF) measure in different settings, including pre-operative heart transplant evaluation.1 Achieving VO2max requires full exertion, which may be limited by frailty and pre-frailty in older adults. Importantly, pre-frailty and frailty are associated with adverse clinical outcomes.2 Whether serial measurements of VO2 and log10-transformed minute ventilation (VE) calculated as a ratio termed ‘oxygen uptake efficiency slope’ (OUES)3 is useful in older adults with or without frailty and pre-frailty remains unexplored