https://immattersacp.org/weekly/archives/2014/12/16/4.htm

Emphysema on CT may be an important independent risk factor for death

Emphysema found on computed tomography (CT) was associated with an increased risk for mortality among people without airflow obstruction or chronic obstructive pulmonary disease (COPD), a study found.


Emphysema found on computed tomography (CT) was associated with an increased risk for mortality among people without airflow obstruction or chronic obstructive pulmonary disease (COPD), a study found.

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To determine the prognostic significance of emphysema-like lung among patients without COPD, researchers conducted a prospective cohort study among 2,965 patients aged 45 to 84 years who had no COPD on spirometry for 6 years. The study population was adapted from MESA (Multi-Ethnic Study of Atherosclerosis), which enrolled patients from 2000 to 2002 from 6 study sites across the U.S. Each patient had cardiac CT at baseline as part of that study.

Results appeared in the Dec. 16 Annals of Internal Medicine.

There were 186 deaths over a median of 6.2 years, for a mortality rate of 10.0 per 1,000 person-years. Greater emphysema-like lung was associated with higher mortality (adjusted hazard ratio [HR] per one-half interquartile range [IQR], 1.14; 95% CI, 1.04 to 1.24; P=0.004) after adjustment for potential confounders, including cardiovascular risk factors and FEV1. Potential mediators minimally attenuated the results (HR per half-IQR of emphysematous voxels, 1.13; 95% CI, 1.04 to 1.24; P=0.006).

Associations with mortality were strengthened after exclusion of patients below the fifth percentile and above the 95th percentile for emphysematous voxels (HR per half-IQR, 1.27; 95% CI, 1.09 to 1.48; P=0.002). An additive model showed little evidence for a nonlinear relationship (P for linear term=0.006; P for nonlinearity=0.22)

The authors wrote, “These findings suggest that emphysema confers excess risk independent of spirometrically defined COPD. Clinical appreciation of the prognostic implications of emphysema on CT and investigation of therapies specifically targeting emphysema, of which there are none, are warranted.”