Association between asthma, corticosteroids and allostatic load biomarkers: a cross-sectional study

Background Allostatic load, a measure of early ageing or ‘wear and tear’ from adapting to environmental challenges, has been suggested as a framework with which to understand the stress-related disruption of multiple biological systems which may be linked to asthma. Considering the socioeconomic context is also critical given asthma and allostatic overload are more common in lower socioeconomic groups. Aims Estimate the relationship between allostatic load and its constituent biomarkers, asthma and corticosteroid prescribing while controlling for socioeconomic status. Methods Data from Understanding Society (a nationally representative survey of UK community-dwelling adults) waves 1–3 (2009–2012) allowed the identification of a sex-specific risk profile across 12 biomarkers used to construct an Allostatic Load Index for a sample of 9816 adults. Regression analyses were used to examine the association of asthma status and corticosteroid prescriptions with allostatic load and its constituent biomarkers while controlling for socioeconomic status (n=9805). Results Subjects with currently treated asthma and no corticosteroid prescription have an allostatic load 1.21 times higher than those without asthma (p<0.001). Asthmatic subjects in receipt of inhaled corticosteroids had an allostatic load, approximately 1.12 times higher than those without asthma (p<0.001). This association persisted in sensitivity analyses and appeared to be driven by an association with specific biomarkers (dehydroepiandrosterone-sulfate, waist-to-height ratio and C-reactive protein). Conclusion Early ageing, in the form of a higher allostatic load, was present even in the mildest asthma group not receiving inhaled corticosteroids. Allostatic load is helpful in understanding the increased all-cause mortality and multimorbidity observed in asthma.