Mortality Risk From Damaged Bronchi Extends to People Without COPD

Bronchiectasis was associated with an increased mortality risk in current and former smokers even if they did not meet the spirometric criteria for chronic obstructive pulmonary disease (COPD), an observational study found.

Compared with patients without suspected bronchiectasis, the 10-year mortality risk was greater among patients who had suspected bronchiectasis — evidenced by CT and clinical presentation — whether they had normal spirometry (difference in mortality probability [Pr] 0.15, 95% CI 0.09-0.21) or obstructive spirometry (Pr 0.06, 95% CI 0.03-0.09).

However, the relationship between bronchiectasis and mortality was inconclusive for people with preserved ratio impaired spirometry (PRISm; Pr 0.07, 95% CI -0.003 to 0.15), reported Alejandro Diaz, MD, MPH, of Harvard Medical School in Boston, and coauthors in the Annals of Internal Medicine.

“These findings support including lung imaging as a tool for clinically defining bronchiectasis and for COPD workup to improve patient care,” the group wrote.

If a patient has CT images with incidental features of bronchiectasis and presents with respiratory symptoms, “it is worthy to do a workup for bronchiectasis to determine the cause,” Diaz told MedPage Today via email.

Study authors noted that bronchiectasis, the chronic thickening of the lung’s airways due to inflammation and infection, often overlaps with COPD. They cited prior work showing that bronchiectasis has been observed in 4% to 72% of adult COPD patients who, in turn, tend to be at particularly high risk of mortality and suffer more exacerbations than those with either COPD or bronchiectasis alone.

It is notable that the mortality risk associated with bronchiectasis is not confined to COPD based on the new report. “The results were surprising for smoking people with normal lung function because this population is, in general, less sick than their counterparts with a lung disease established,” Diaz said.

Diaz and colleagues had performed a secondary analysis of the Genetic Epidemiology of Chronic Obstructive Pulmonary Disease (COPDGene) study, which ran from November 2007 to April 2011 and included patients from 21 U.S. clinical centers. COPD patients and non-COPD controls underwent spirometry as well as standardized volumetric CT scans three times over the course of 10 years.

A total of 7,662 participants with 10 or more pack-years of smoking history were included in the present report. Just over half of the patients were women and the average patient age was 60 years. Study authors found that 3,277 had normal spirometry results, 3,399 were obstructed, and 986 had results that indicated PRISm.

Suspected bronchiectasis was identified in 17.6% of the cohort.

Diaz’s group employed artificial intelligence-based measurements of airway-to-artery ratio (AAR) to objectively define bronchial dilatation. Suspected bronchiectasis was defined as an AAR >1 of greater than 1% plus two of the following: cough, phlegm, dyspnea, and history of multiple exacerbations.

Unlike previous studies about mortality in the COPD-bronchiectasis overlap, the present report is not limited to people with moderate-to-severe lung function impairment and does not rely solely on subjective CT measures of bronchiectasis, the authors pointed out.

After an average follow-up of 11 years, 27.3% of patients included in the study had died.

In instances where bronchiectasis was supported only by objective CT imaging and not by symptoms or history of exacerbations, the finding was no longer associated with death in people with normal spirometry (Pr 0.04, 95% CI -0.001 to 0.08).

Researchers cautioned that only two racial groups were included in the analysis, non-Hispanic Black and non-Hispanic white patients, which might limit the applicability of the findings to other groups.

Other limitations include the observational nature of the study, and using airway dilation as the only radiologic feature when defining suspected bronchiectasis.

“The association between suspected bronchiectasis and higher risk for death can be explained by several factors: systemic inflammation that is shared by cigarette smoking and the airway abnormality, vascular changes (such as small pulmonary vessel pruning associated with bronchiectasis), frequent acute exacerbations, and sputum pathogens,” the researchers wrote.

“Further studies are needed to understand the relationship between bronchiectasis, tobacco smoke, and clinical outcomes in smoking populations with preserved lung function,” they continued.

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