Relationship of ventilatory inefficiency and low cardiorespiratory fitness in the elderly: a retrospective observational study

Abstract Objectives : To check if ventilatory inefficiency is related to low cardiorespiratory fitness in the elderly and to identify the variable(s) of the cardiopulmonary exercise test (CPET) best suited to determining this relationship. Methods : A retrospective analysis of 1357 CPETs was performed. Sixty-one subjects over 60 years old with a ventilatory efficiency slope (VE/VCO2) index >35 were selected and divided into two groups: low cardiorespiratory fitness (VO2<80% predicted) (n=22) and normal cardiorespiratory fitness (VO2>80% predicted) (n=39) and were compared with a control group of healthy elderly persons with normal cardiorespiratory fitness and VE/VCO2 slope index <35 (n=16), matched by gender, weight, height, and age. Results : Oxygen consumption had a low correlation with VE/VCO2 slope (r= -0.35, p<0.01), a moderate correlation with the cardiorespiratory optimal point (COP) (r= -0.59, p<0.001) and a strong correlation with oxygen uptake efficiency Slope (OUES) =0.92, p<0.0001). In relation to the ROC curve, the VE/VCO2 slope presented an area under the curve of 0.65, but without statistical significance (p> 0.05); the COP showed an area under the curve of 0.84 (p <0.0001) and the OUES presented an area under the curve of 0.81 (p<0.0001). Conclusion : Ventilatory inefficiency is related to poor cardiorespiratory fitness in the elderly. The COP and OUES were more accurate at predicting low cardiorespiratory fitness.