Single-Breath Simultaneous Measurement of DLNO and DLCO as Predictor of the Emphysema Component in COPD – A Retrospective Observational Study

Roberto W Dal Negro,1 Paola Turco,1 Massimiliano Povero2 1National Centre for Respiratory Pharmacoeconomics and Pharmacoepidemiology - CESFAR, Verona, Italy; 2AdRes Health Economics and Outcomes Research, Turin, ItalyCorrespondence: Massimiliano Povero, Email [email protected]: Chronic Obstructive Pulmonary Disease (COPD) is a respiratory condition characterized by heterogeneous abnormalities of the airways and lung parenchyma that cause different clinical presentations. The assessment of the prevailing pathogenetic components underlying COPD is not usually pursued in daily practice, also due to technological limitations and cost.Aim: To assess non-invasively the lung emphysema component of COPD by the simultaneous measurement of DLNO and DLCO via a single-breath (sDLNO and sDLCO).Methods: COPD patients aged ≥ 40 years of both genders were recruited consecutively and labelled by computed tomography as “with significant” emphysema (> 10% of CT lung volume) or “with negligible” emphysema otherwise. Current lung function tests such as sDLNO, sDLCO and Vc (the lung capillary blood volume) were measured. All possible subsets of independent spirometric and diffusive parameters were tested as predictors of emphysema, and their predicted power compared to each parameter alone by ROC analysis and area under the curve (AUC).Results: Thirty-one patients with “significant emphysema” were compared to thirty-one with “negligible emphysema”. FEV1 and FEV1/FVC seemed to be the best spirometric predictors (AUC 0.80 and 0.81, respectively), while sDLCO and Vc had the highest predicted power among diffusive parameters (AUC 0.92 and 0.94, respectively). sDLCO and Vc values were the parameters most correlated to the extent of CT emphysema. Six subsets of independent predictors were identified and included at least one spirometric and one diffusive parameter. According to goodness-to-fit scores (AIC, BIC, log-likelihood and pseudo R2), RV coupled with sDLCO or Vc proved the best predictors of emphysema.Conclusion: When investigating the parenchymal destructive component due to emphysema occurring in COPD, sDLNO, sDLCO and Vc do enhance the predictive power of current spirometric measures substantially. sDLNO, sDLCO and Vc contribute to phenotype of the main pathogenetic components of COPD easily and with high sensitivity. Organizational problems, radiation exposure, time and costs could be reduced, while personalized and precision medicine could be noticeably implemented.Keywords: COPD, parenchymal destruction, emphysema, lung capillary blood volume, simultaneous single-breath NO and CO diffusing capacity, precision medicine