The Prognostic Performance of Lung Diffusing Capacity in Preserved Ratio Impaired Spirometry: An Observational Cohort Study

• Published in: International journal of chronic obstructive pulmonary disease 2022-11, Vol.17, p.2791-2799
• Main Authors: Ogata, Hiroaki, Sha, Kachi, Kotetsu, Yasuaki, Enokizu-Ogawa, Aimi, Katahira, Katsuyuki, Ishimatsu, Akiko, Taguchi, Kazuhito, Moriwaki, Atsushi, Yoshida, Makoto
• Format: Article
• Language: English
• Subjects: Age; all-cause mortality; Analysis; Asthma; Biomarkers; Body mass index; Chronic obstructive pulmonary disease; Cohort analysis; diffusing capacity of the lungs; Gender; Health aspects; Japan; Lung diseases, Obstructive; Medical prognosis; Medical records; Mortality; Observational studies; Original Research; Patients; preserved ratio impaired spirometry; Prognosis; Regression analysis; Risk factors; Spirometry; Variance analysis
• ISSN: 1178-2005; 1176-9106; 1178-2005
• DOI: 10.2147/COPD.S384074

Purpose: Similar to chronic obstructive pulmonary disease (COPD), the diffusing capacity of the lung ([D.sub.LCO]) might be decreased and associated with poor prognosis in preserved ratio impaired spirometry (PRISm), a clinical entity as a prodromal phase of COPD. The aims of the present study were to evaluate the distributions of [D.sub.LCO] and to assess the association between [D.sub.LCO] and mortality among subjects with PRISm. Patients and Methods: We conducted an observational cohort study at the National Hospital Organization Fukuoka National Hospital. We classified the 899 patients [greater than or equal to] 40 years of age with an assessment of [D.sub.LCO] into five groups based on spirometry: preserved spirometry, PRISm, mild COPD, moderate COPD, and severe/very severe COPD. The prevalence of low [D.sub.LCO] (< 80% per predicted) was compared among the five groups. Using PRISm patients with follow-up data, we further investigated the association of low [D.sub.LCO] with all-cause mortality. Results: The prevalence of low [D.sub.LCO] in the PRISm group (58.8%) was significantly higher than that in the preserved-spirometry group (21.8%), the mild-COPD group (23.5%), and the moderate-COPD group (36.0%) (all P < 0.01), and it was comparable to that in the severe/very severe-COPD group (63.2%). The results remained unchanged after adjusting for potential confounders. Among the PRISm subjects, the overall survival rate was significantly lower in the low-[D.sub.LCO] group than in the preserved-[D.sub.LCO] group (P < 0.01). The multivariable-adjusted hazard ratio (HR) for all-cause mortality was significantly higher in the low-[D.sub.LCO] group than in the preserved-[D.sub.LCO] group (HR = 10.10 (95% confidence interval 2.33-43.89)). Conclusion: Diffusing capacity was more impaired in PRISm subjects than in those with preserved spirometry or mild to moderate COPD. Regarding PRISm, low [D.sub.LCO] was a significant risk factor for all-cause mortality. Clinicians should assess [D.sub.LCO] in the management of PRISm to predict the future risk of overall death. Keywords: preserved ratio impaired spirometry, chronic obstructive pulmonary disease, diffusing capacity of the lungs, all-cause mortality