Diffusing capacity predicts all-cause mortality in COPD patients

A measure of petrol transfer called diffusing capacity, which is independent of the BODE score, computed tomography (CT) indications of emphysema, and airway wall thickness, significantly predicted all-cause death in people with chronic obstructive pulmonary disease (COPD), says an article published in Annals of American Thoracic Society.

The BODE (body mass index, obstruction, dyspnea, exercise capacity) index, which takes into account factors like body mass index, forced expiratory volume in 1 second, dyspnea score, and 6-minute walk distance, is frequently used to calculate the mortality risk associated with chronic obstructive pulmonary disease. A potential predictor of mortality that reflects physiological characteristics different from those in the BODE index is the lung's diffusing capacity for carbon monoxide (DlCO). Hence, utilizing individuals from the COPD Gene study, Aparna Balasubramanian and team conducted this study to assess DlCO as a predictor of mortality.

Individuals with COPD (previous or current smokers with forced expiratory volume in 1 second/forced vital capacity 0.7) and DlCO readings from the COPDGene phase 2 visit were subjected to time-to-event analysis. Age, sex, pack-years, smoking habits, BODE index, computed tomography percent emphysema (low attenuation areas below 950 Hounsfield units), CT airway wall thickness, and history of cardiovascular or kidney diseases were all taken into account when modelling survival using Cox proportional hazard methods. The discriminative accuracy of models using DlCO and BODE scores was compared using C statistics.

The key findings of this study were:

1. 393 (16.8%) of the 2,329 individuals passed away during the follow-up period (median = 4.9 years).

2. According to adjusted analysis, mortality increased by 28% for every 10% drop in DlCO percent anticipated (hazard ratio = 1.28; 95% confidence interval, 1.17-1.41, P 0.001).

3. DlCO % predicted performed similarly to BODE when compared to other clinical predictors (C statistic DlCO = 0.68; BODE = 0.70), and the addition of DlCO to BODE increased its discriminative accuracy (C statistic = 0.71).

Reference:

Balasubramanian, A., Putcha, N., MacIntyre, N. R., Jensen, R. L., Kinney, G., Stringer, W. W., Hersh, C. P., Bowler, R. P., Casaburi, R., Han, M. K., Porszasz, J., Barr, R. G., Regan, E., Make, B. J., Hansel, N. N., Wise, R. A., & McCormack, M. C. (2023). Diffusing Capacity and Mortality in Chronic Obstructive Pulmonary Disease. In Annals of the American Thoracic Society (Vol. 20, Issue 1, pp. 38–46). American Thoracic Society. https://doi.org/10.1513/annalsats.202203-226oc