Distinct childhood respiratory risk factor profiles demonstrated associations with middle-aged lung function and chronic obstructive pulmonary disease (COPD) according to the results of a longitudinal cohort study published in the Annals of the American Thoracic Society. Children with frequent asthma attacks and multiple allergic comorbidities are the most vulnerable group, particularly if they go on to become adult smokers.
It is common for children to have multiple risk factors, and the interplay of these factors may have additive or multiplicative effects, mediation, and confounding. Although risk factors have been identified in past studies, their interaction was not investigated. Determining how these factors aggregate with each other as well as identifying and elucidating specific profiles to clarify which individuals are at greatest risk for adult lung function deficits and COPD is essential.
Researchers in Australia analyzed data from the Tasmanian Longitudinal Health Study and identified profiles of 11 childhood respiratory risk factors, documented at age 7, in 8352 study participants. They then investigated the associations between these 11 risk profiles and postbronchodilator lung function and the prevalence of COPD at age 53, the influence of childhood lung function and adult asthma, and interaction with personal smoking.
A total of 6 risk profiles were identified: unexposed or least exposed (49%); parental smoking (21.5%); allergy (10%); frequent asthma, bronchitis (8.7%); infrequent asthma, bronchitis (8.3%); and frequent asthma, bronchitis, allergy (2.6%). The last profile (profile 6) demonstrated the strongest association with lower forced expiratory volume in 1 second (FEV1; –261 mL), lower FEV1/forced vital capacity (–3.4), and increased risk for COPD (odds ratio 4.9) at age 53. Active adult asthma largely mediated the effect of profile 6 on COPD (62.5%), and reduced childhood lung function accounted for another 26.5%. Of note, the presence of either profile 2 or 6 was synergistic for smokers.
The authors noted the strong association between the parental smoking profile and COPD without current asthma, which they believe highlights the long-term adverse effect of smoking exposure in childhood on adult lung function and COPD.
Potential attrition bias is one study limitation; however, as attrition was not associated with exposure, this was unlikely to have affected the study findings. The researchers also noted a lack of information on birth weight and gestational age, which can be associated with poorer lung function very early in life; however, a 32% subsample from the study representing 32% of the total study sample, found that birth weight of the risk profiles did not differ significantly from the reference profile.
The authors suggested that their findings may help develop potential risk prediction tools to identify individuals at high risk as well as interventions to reduce the long-term lung health impairment associated with these risk profiles. Furthermore, the finding that active adult asthma mediates 63% to 82% of the total effects of 2 childhood asthma-related profiles on middle-aged COPD raises the possibility that optimal asthma control during the course of a lifetime may diminish the adverse effect of childhood asthma-related profiles.
Bui DS, Walters HE, Burgess JA, et al. Childhood respiratory risk factor profiles, their Interactions and mediators, and middle-age lung function: a prospective cohort study from the 1st to 6th decade [published online June 12, 2018]. Ann Am Thorac Soc. doi:10.1513/AnnalsATS.201806-374OC