Association of Gas Diffusing Capacity of the Lung for Carbon Monoxide with Cardiovascular Morbidity and Survival in a Disadvantaged Clinical Population.

Purpose: Low diffusing capacity of the lung for carbon monoxide (D _LCO ) and spirometry values are associated with increased mortality risk. However, associations between mortality risk and cardiovascular disease with the transfer coefficient of the lung for carbon monoxide (K _CO ) and alveolar volume (V _A ) are unknown. This cohort study: (i) evaluated whether D _LCO , K _CO , and V _A abnormalities are independently associated with cardiovascular morbidity and/or elevated mortality risk and, (ii) compared these associations with those using spirometry values.
Methods: Gas-diffusing capacity and spirometry data of 1165 adults seen at specialist respiratory outreach clinics over an 8-year period (241 with cardiovascular disease; 108 deceased) were analysed using multivariable Cox and logistic regression.
Results: D _LCO , K _CO , and V _A values below the lower limit of normal (< - 1.64 Z-scores) were associated with elevated cardiovascular disease prevalence [respective odds ratios of 1.83 (95% CI 1.31-2.55), 1.56 (95% CI 1.08-2.25), 2.20 (95% CI 1.60-3.01)] and increased all-cause mortality risk [respective hazard ratios of 2.99 (95% CI 1.83-4.90), 2.14 (95% CI 1.38-3.32), 2.75 (95% CI 1.18-2.58)], after adjustment for factors including age, personal smoking, and respiratory disease. Compared to similar levels of spirometry abnormality, D _LCO , K _CO , and V _A were associated with similar or greater mortality risk, and similar cardiovascular disease prevalence. Analysis of only those patients with clinical normal spirometry values (n = 544) showed these associations persisted for D _LCO .
Conclusion: Low D _LCO , K _CO , and V _A measurements are associated with cardiovascular disease prevalence. As risk factors of all-cause mortality, they are more sensitive than spirometry even among patients with no diagnosed respiratory disease.
(© 2022. The Author(s).)