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Low FVC/TLC in Preserved Ratio Impaired Spirometry (PRISm) is associated with features of and progression to obstructive lung disease.

  • Author(s): Fortis, Spyridon;
  • Comellas, Alejandro;
  • Kim, Victor;
  • Casaburi, Richard;
  • Hokanson, John E;
  • Crapo, James D;
  • Silverman, Edwin K;
  • Wan, Emily S
  • et al.

One quarter of individuals with Preserved Ratio Impaired Spirometry (PRISm) will develop airflow obstruction, but there are no established methods to identify these individuals. We examined the utility of FVC/TLC in identifying features of obstructive lung disease. The ratio of post-bronchodilator FVC and TLCCT from chest CT (FVC/TLCCT) among current and former smokers with PRISm (FEV1/FVC ≥ 0.7 and FEV1 < 80%) in COPDGene was used to stratify subjects into quartiles: very high, high, low, and very low. We examined the associations between FVC/TLCCT quartiles and (1) baseline characteristics, (2) respiratory exacerbations, (3) progression to COPD at 5 years, and (4) all-cause mortality. Among participants with PRISm at baseline (n = 1,131), the very low FVC/TLCCT quartile was associated with increased gas trapping and emphysema, and higher rates of progression to COPD at 5 years (36% versus 17%; p < 0.001) relative to the very high quartile. The very low FVC/TLCCT quartile was associated with increased total (IRR = 1.65; 95% CI [1.07-2.54]) and severe (IRR = 2.24; 95% CI [1.29-3.89]) respiratory exacerbations. Mortality was lower in the very high FVC/TLCCT quartile relative to the other quartiles combined. Reduced FVC/TLCCT ratio in PRISm is associated with increased symptoms, radiographic emphysema and gas trapping, exacerbations, and progression to COPD.

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