Early Adult Lung Function Linked to Development of COPD

Susan London

July 08, 2015

Poorer lung function in early adulthood may be sufficient to predispose an individual to chronic obstructive pulmonary disease (COPD) later in life, suggests a retrospective cohort study published in the July 9 issue of the New England Journal of Medicine.

The study of more than 2500 individuals from the Danish and US populations found that about half of those who ultimately developed COPD had a low forced expiratory volume in 1 second (FEV1) before the age of 40 years, but a normal decline in this measure thereafter.

"[T]he results of this study suggest that the classic trajectory of an accelerated decline in FEV1 from a normal level is not an obligate feature of COPD and that a substantial proportion of the persons in whom COPD develops have a low FEV1 level in early adulthood," write the investigators, led by Peter Lange, MD, DrMedSc, from the Institute of Public Health, Section of Social Medicine, the Respiratory Section at the Hvidovre Hospital, and the Copenhagen City Heart Study at the Frederiksberg Hospital, all in Denmark.

In an accompanying editorial, Frank E. Speizer, MD, from the Channing Division of Network Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, and James H. Ware, PhD, from the Harvard School of Public Health, also in Boston, note that factors unrelated to smoking, such as environmental pollution, occupational exposures, genetics, and asthma, may affect pulmonary function in early adulthood, as well as its decline thereafter. In addition, some of the rate of change of FEV1 may reflect disease activity, rather than disease severity.

"To sort out these additional components of COPD risk definitively will require large data sets with repeated measurements of diverse population groups across the life course. Few groups of investigators or institutions have or can make the commitment to carry out such studies," they write.

"For the present, two messages remain clear," the editorialists conclude. "Spirometric measurements, both in population studies and in the clinical setting, continue to provide the best predictive measure of both the risk of COPD development and the severity of disease status in those with obstruction. Furthermore, it is important to continue to focus on cigarette smoking, which remains the major risk factor for the development of disease."

In the current study, the researchers analyzed data from three cohorts: the Framingham Offspring Cohort, the Copenhagen City Heart Study, and the Lovelace Smokers Cohort. Participants in each cohort had serial spirometry beginning at baseline. Overall, 12% of 264 participants who underwent spirometry before age 40 years and again at least a decade later met criteria for COPD after an average of 22 years of follow-up.

The incidence of COPD was significantly higher among individuals who had an FEV1 of less than 80% of the predicted value before 40 years of age compared with those who had a higher FEV1 during that time of their life (26% vs 7%; P < 0.001).

Forty-eight percent of the participants who developed COPD had had a normal FEV1 before age 40 years and experienced a rapid drop in FEV1 thereafter, with a mean decline of 53 mL per year. The other 52% had had a low FEV1 before age 40 years and experienced a significantly smaller subsequent mean decline in FEV1 of 27 mL per year, even though they had similar smoking exposure.

The Copenhagen City Heart Study was supported by GlaxoSmithKline, the Capital Region of Copenhagen, the Danish Heart Foundation, the Danish Lung Foundation, and the Velux Foundation. The Lovelace Smokers Cohort was supported by the State of New Mexico (appropriation from the Tobacco Settlement Fund) and by grants from the National Institutes of Health. Full conflict-of-interest information is available on the journal's website.

N Engl J Med. 2015;373:111-122, 185-186.

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