Identification of COPD Patients at High Risk for Lung Cancer Mortality Using the COPD-LUCSS-DLCO

Abstract

Background: The COPD-Lung Cancer Screening Score (COPD-LUCSS) is a tool designed to help identify patients with COPD with the highest risk of developing lung cancer (LC). The COPD-LUCSS includes the determination of radiological emphysema, a potential limitation for its implementation in clinical practice. The diffusing capacity for carbon monoxide (DLCO) is a surrogate marker of emphysema and correlates well with CT-determined emphysema.

Objective: To explore the use of the COPD-LUCSS using the DLCO instead of radiological emphysema, as a tool to identify patients with COPD at higher risk of LC death.

Methods: The Body Mass Index, Airflow Obstruction, Dyspnea, Exercise Performance international cohort database was analyzed. By logistic regression analysis, we confirmed that the other parameters included in the COPD-LUCSS (age > 60, pack-years > 60, BMI < 25) were independently associated with LC death. We selected the best cutoff value for DLCO that independently predicted LC death. We then integrated the new COPD-LUCSS-DLCO assigning points to each parameter according to its hazard ratio value in the Cox regression model. The score ranges from 0 to 8 points.

Results: By regression analysis, age > 60, BMI <25 kg/m(2), pack-year history > 60, and DLCO < 60% were independently associated with LC diagnosis. Two COPD-LUCSS-DLCO risk categories were identified: low risk (scores 0-3) and high risk (scores 3.5-8). In comparison to patients at low risk, risk of death from LC increased 2.4-fold (95% CI, 2.0-2.7) in the high-risk category.

Conclusions: The COPD-LUCSS using DLCO instead of CT-determined emphysema is a useful tool to identify patients with COPD at risk of LC death and may help in its implementation in clinical practice.

Keywords: DLCO; chronic obstructive pulmonary disease; lung cancer; screening.