A study using a new definition of meet the criteria.
The population-based cohort looked at individuals who had been exposed to at least 10 pack-years, and defined early COPD as the ratio of forced expiratory volume to forced vital capacity being less than the lower limit of normal (FEV1/FVC less than LLN). The definition of early COPD, published in 2018 (Am J Resp and Crit Care Med. 2018;197:1540-51), also included the presence of abnormalities on a CT scan or a decline in FEV1 (greater than 60 mL/year) that is accelerated relative to FVC, but the new population study did not include the latter two criteria.
The researchers, under corresponding author Peter Lange, MD, of the University of Copenhagen found that those with early COPD were more likely to have chronic respiratory symptoms, severe impairment of lung function, acute respirator hospitalization, and early mortality at baseline and at follow-up. The work was published in the American Journal of Respiratory and Critical Care Medicine.
“To dig through the smokers and try to figure out which smokers are more at risk than other smokers is probably the best way to summarize what they’ve done here,” said Robert Reed, MD, from the University of Maryland, Baltimore, in an interview. However, he added that he would like to see the research extended to an even younger population, as well as nonsmokers. “We don’t need all of this information to tell us that smoking is bad. I think nonsmokers would be really interesting – creating a definition of COPD that excludes patients that meet the usual definition for COPD would be of potential interest,” added Dr. Reed, who was not involved in the study.
Using a cohort of 105,630 randomly selected individuals from Danish nationwide health registries, the study identified 8,064 individuals aged under 50 years with 10 or more pack-years of tobacco exposure. In this group, 1,175 (15%) had early COPD, of whom 58% were current smokers. The cohort of smokers was followed for up to 14.4 years. Multivariate analyses found that those with early COPD, compared with smokers without COPD, were at substantially greater risk of acute obstructive lung disease hospitalization (hazard ratio, 6.42; 95% confidence interval, 3.39-12.2), acute pneumonia hospitalization (HR, 2.03; 95% CI, 1.43-2.88), and all-cause mortality (HR, 1.79; 95% CI, 1.28-2.52).
There is value in gaining a better understanding of which smokers are at greatest risk of COPD down the line, but data on younger people, even 30-year-olds, could guide therapeutic decisions when and if new drugs that can alter the state of the disease become available. Focusing more on younger, high-risk patients could also be used to create greater incentives to quit smoking, though Dr. Reed has mixed feelings even about that. “What if we identified 15% of smokers that are at risk of COPD, and the other 85% say, ‘I’ll keep smoking,’ and they fall over dead from a heart attack?” said Dr. Reed, noting that smoking has a wide range of known risks. “They should all stop,” he added.
The study also captures a wide range of patients, from some with early disease that will likely progress to COPD later in life along with some who already developed full-blown COPD in, for example, their early 40s. “Those are very different patients and to lump them together is potentially problematic,” said Dr. Reed. More granulated data could potentially inform more personalized medicine, and the discovery and verification of genetic risk factors.
Nevertheless, Dr. Reed expects the data to move the field forward. “They created a nice, rich database that I think will generate a lot more analysis and discussion.”
The study was funded by the Lundbeck Foundation. One of the authors has received support from the National Institute for Health Research Manchester (England) Biomedical Research Centre. Dr. Reed has no relevant financial disclosures.
SOURCE: Colak Y et al. Am J Resp Crit Care Med. 2019 Nov 26. doi: 10.1164/rccm.201908-1644OC