Body mass index trajectories from childhood to middle age and related incidence, persistence and relapse of asthma from 43 to 53 years of age: a longitudinal cohort study

Abstract

Abstract <b>Background:</b> The impact of life-time body mass index (BMI) trajectories on the development or persistence of adult asthma is unknown. <b>Objective:</b> We investigated associations between BMI trajectories from childhood to middle age (5-43 years) and the incidence, persistence or relapse of asthma from ages 43 to 53 years. <b>Methods:</b> Weight and height were measured between 5 and 43 years at 8-time points in the Tasmanian Longitudinal Health Study (n= 8583). BMI trajectories were developed using group-based trajectory modelling. Associations between BMI trajectories and: asthma incidence, persistence, and relapse from 43 to 53 years; bronchial hyper-responsiveness (BHR) at 50 years; and bronchodilator response at 53 years were modelled using multiple logistic and linear regression. <b>Results:</b> Five distinct BMI trajectories were identified: average, low, high, child high-decreasing and child average-increasing. Compared to the average trajectory, child average-increasing (OR=2.6; 95%CI 1.1, 6.6) and high (OR=4.4; 1.7, 11.4) trajectories were associated with increased risk of incident asthma and BHR in middle age (OR= 2.9; 1.1, 7.5 and OR= 3.5;1.1, 11.4, respectively). No associations were observed for asthma persistence or relapse. <b>Conclusion:</b> Participants with high and persistently increasing BMI trajectories from childhood to middle age were at higher risk of incident adult asthma. Encouraging individuals to maintain normal BMI over the life course may help reduce the burden of adult asthma.