People with high and persistently increasing BMI trajectories from childhood through to middle age are at high risk of incident adult asthma, Australia research shows.
According to data from the Tasmanian Longitudinal Health Study presented at the ERS 2021 Congress this week, encouraging individuals to maintain a normal BMI over the life course may help reduce the burden of adult new-onset asthma.
Height and weight measurements of more than 4,000 participants were recorded at eight time points between 5 and 43 years and used to calculate BMI trajectories.
The incidence, persistence or relapse of asthma were recorded from age 43 to 53 years and bronchial hyperresponsiveness (BHR) was measured at age 50 years.
Ms Gulshan Ali, a PhD candidate in the Melbourne School of Population and Global Health’s Allergy and Lung Health Unit, said the study identified five distinct BMI trajectories – average (50.3%), low (26.7%), high (3.1%), child high-decreasing (14.1%) and child average-increasing (5.8%).
BMI trajectories of child average-increasing (OR=2.6; 95% CI 1.1, 6.6) and high (OR=4.4; 1.7, 11.4) 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).
Ms Ali said there was no association between BMI trajectories and persistent or relapsed asthma.
“In addition to BHR, we found that the proportion of other respiratory adverse outcomes were also high in these two high BMI trajectories at 43 and 53 years. This suggests that there could be a physiologic abnormality in these individuals at high BMI trajectories.”
She said this could be related to an adiposity-related systemic inflammation or secretion of various immunologically active factors.
The study found the risk of incident asthma was almost double for those with persistent obesity from childhood to middle age compared to those who have obesity only during adult life.
“In contrast, these adverse respiratory outcomes were lower in the child-high-decreasing trajectory which suggests that early life adiposity does not carry a risk alone unless it persists from early life to adulthood.”
Ms Ali said previous studies, which had found conflicting evidence for the association between obesity and asthma, were based on single time-point BMIs which did not consider the dynamic changes in adiposity.