Distinct Lung Function Trajectories Associated With COPD Risk

Chronic obstructive pulmonary disease (COPD) development may be associated with distinct lung function trajectories from the first to sixth decade of life, according to a study published in Lancet Respiratory Medicine.

Researchers collected data from 6 waves of the Tasmanian Longitudinal Health Study, which began in 1968, enrolling children born in 1961. The children underwent clinical examinations, including prebronchodilator spirometry. Follow-up was performed at ages 13, 18, 45, 50, and 53 years. In the present study, prebronchodilator forced expiratory volume in 1 second (FEV₁) z-scores at 6 time points were analyzed to model lung function trajectories.

Of the original 8583 participants, 2689 had both prebronchodilator and postbronchodilator spirometry at age 53. The researchers included 2438 participants who had at least 2 waves of lung function data at age 7 and 53 in the present analysis. The 6 trajectories identified were categorized as early below average, accelerated decline; persistently low; early low, accelerated growth, normal decline; persistently high; below average; and average.

Compared with the average group, the trajectories early below average, accelerated decline; persistently low; and below average had an increased risk for COPD at age 53 (odds ratio [OR], 35.0; 95% CI, 19.5-64.0; OR, 9.5; 95% CI, 4.5-20.6; and OR, 3.7; 95% CI, 1.9-6.9, respectively). Childhood asthma, parental asthma, maternal smoking, bronchitis, pneumonia, allergic rhinitis, and eczema were early-life predictors of these 3 trajectories.

Furthermore, personal smoking and adult asthma increased the effect of maternal smoking and childhood asthma, respectively, on the early below average, accelerated decline trajectory.

Of the 6 potential FEV₁ trajectories identified, 2 were novel (early below average, accelerated decline and early low, accelerated growth, normal decline), and 3 trajectories (early below average, accelerated decline; below average; and persistently low) were responsible for 75% of the COPD burden.

One potential limitation of this study is that Global Lung Function Initiative reference equations were unavailable in 1968 when the Tasmanian Longitudinal Health Study began, and equipment has changed over the years. This may have led to an “imperfect fit” of the equations at different time points. In addition, the last spirometry measurement was conducted at an age when COPD is just beginning to emerge because most people with COPD are diagnosed in their 60s, which means the effect of these lung trajectories on COPD could become clearer in the future.

“Clinicians and patients with asthma should be made aware of the potential long-term implications of non-optimal asthma control for lung function trajectory throughout life, and the role of benefit of optimal asthma control on improving lung function should be investigated in future intervention trials,” the researchers concluded.

Reference

Bui DS, Lodge CJ, Burgess JA, et al. Childhood predictors of lung function trajectories and future COPD risk: a prospective cohort study from the first to the sixth decade of life [published online April 5, 2018]. Lancet Respir Med. doi:10.1016/S2213-2600(18)30100-0