Childhood respiratory risk factor profiles, their interactions and mediators, and middle-age lung function: a prospective cohort study from the 1st to 6th decade

RATIONALE: Childhood risk factors for long-term lung health often co-exist and their specific patterns may affect subsequent lung function differently. OBJECTIVES: To identify childhood risk factor profiles, their influence on lung function and chronic obstructive pulmonary disease (COPD) in middle-age and potential pathways. METHODS: Profiles of 11 childhood respiratory risk factors, documented at age 7, were identified in 8352 participants from the Tasmanian Longitudinal Health Study using latent class analysis. We investigated: associations between risk profiles and lung function, and COPD at age 53; mediation by childhood lung function and adult asthma; and interaction with personal smoking. RESULTS: Six risk profiles were identified: 1-"unexposed or least exposed" (49%), 2-"parental smoking" (21.5%), 3-"allergy" (10%), 4-"frequent asthma, bronchitis" (8.7%), 5-"infrequent asthma, bronchitis" (8.3%) and 6-"frequent asthma, bronchitis, allergy" (2.6%). Profile 6 was most strongly associated with lower FEV1:(-261;95%CI:-373,-148 mL); lower FEV1/FVC:(-3.4; -4.8,-1.9%) and increased COPD risk (OR:4.9; 2.1,11.0) at age 53. The effect of profile 6 on COPD was largely mediated by adult active asthma (62.5%) and reduced childhood lung function (26.5%). Profiles 2 and 4 had smaller adverse effects than profile 6. Notably effects of profiles 2 and 6 were stronger for smokers. CONCLUSIONS: Profiles of childhood respiratory risk factors predict middle-age lung function and COPD risk. Adult active asthma is a dominant mediator in associations between childhood asthma-related risk profiles and middle-age lung function/COPD. Specifically, children with frequent asthma attacks and allergies, especially if they also become adult smokers, are the most vulnerable group that should be targeted for interventions.