Prediction of Post-operative Morbidity and Mortality in Patients with Lung Cancer: Methodological Issues

Excerpt

I was interested to read the paper by Yakal et al. published in Lung 2018 [1]. Peak oxygen consumption is a very valuable cardiopulmonary functional parameter in pre-operative evaluation of patients with lung cancer. However, it has several critical limitations for operability decision due to failure in achieving maximal level of exercise test for cases. The authors aimed to reveal the importance of more accurate cardiopulmonary parameters that can be calculated from data of submaximal level test, such as oxygen uptake efficiency slope (OUES) and to determine whether it could be used in the operability decision phase for borderline cases by means of morbidity and mortality. One hundred and twenty-five patients who were scheduled to undergo lung surgery due to lung cancer were included in the study. The OUES value was calculated from the ratio of the peak VO2 value and logarithmic equivalent of the ventilatory volume (V_E). The following equation was used for determining OUES: VO2/log10 V_E. The authors applied different tests such as correlation coefficient, receiver operator characteristic curves, and Kaplan–Meier curve. However, these results are not appropriate estimates for prediction of an outcome. Based on their results, OUES mean value was 12.4 ± 2.1. When the metabolic parameters of the patients were compared, a significant correlation was determined between the peak VO2 value and peak V_E, OUES, and survival (p < 0.01). They concluded that OUES is significantly correlated with peak VO2 and it does not require the performance of maximal exercise and can be used together with peak VO2 in this patient population when there is difficulty in making decision for surgery in patients with lung cancer. …