Aim

To identify optimal thresholds for the VE/VCO2-slope from preoperative cardiopulmonary exercise testing (CPET) to predict major pulmonary complications (MPC) or death following lung cancer surgery.

Methods

Retrospective analysis of 158 patients with lung cancer who underwent lobectomy or pulmectomy during 2008-2020. Main outcome was any MPC or death ?30 days of surgery. Patients were categorized based on CPET using two thresholds corresponding to either 90% sensitivity or 90% specificity for main outcome in ROC-analysis. We compared this with the traditional single threshold of 35. Frequency of complications was compared using Chi2.

Results

The two thresholds, ?30 (90% sensitivity) and ?41 (90% specificity), created three risk groups: low risk (VE/VCO2-slope <30, n=44, 28%); intermediate risk (VE/VCO2-slope 30-41, n=95, 60%) and high risk (VE/VCO2-slope >41, n=19, 12%). The frequency of complications differed between groups: 5%, 16% and 47% (p <0.001). A single threshold of 35 generated a low risk group (n=103, 65%) and a high risk group (n=55, 35%) with 12% vs 26% frequency of complications (p=0.026). Positive predictive values (PPVs) and negative predictive values (NPVs) are listed in table A.

Conclusions

Risk stratification based on three risk groups from preoperative VE/VCO2-slope was more discriminative and generated better PPV and NPV compared to traditional risk stratification into two risk groups.

Table A. Diagnostic values for different thresholds for the VE/VECO2-slope