Influence of age on clinical characteristics, pharmacological management and exacerbations in children with asthma

BackgroundAsthma trials and guidelines often do not distinguish between adolescents and younger children. Using a large English data set, we evaluated the impact of age on asthma characteristics, management and exacerbations.MethodsPrimary care medical records, 2004-2021, were linked to hospital records. Children were categorised by age at diagnosis and followed until the next age bracket. Ages (based on management guidelines) were 5-8 years, 9-11 years and adolescents (12-16 years). Characteristics evaluated included body mass index, allergies and events before and after diagnosis (symptoms, medication). Exacerbation incidence was calculated. Multivariable Cox proportional hazards determined associations with exacerbations.Results119 611 children were eligible: 61 940 (51.8%) 5-8 years, 32 316 (27.7%) 9-11 years and 25 355 (21.2%) adolescents. Several characteristics differed by age; children aged 5-8 years had the highest proportion with eczema, food/drug allergy and cough, but adolescents had the highest proportion with overweight/obesity, aeroallergen sensitisation, dyspnoea and short-acting-beta-agonist only use. Exacerbation rates were highest in the youngest children (per 100 person-years (95% CI): 5-8 years =13.7 (13.4-13.9), 9-11 years =10.0 (9.8-10.4), adolescents =6.7 (6.5-7.0)). Exacerbation risk factors also differed by age; 5-8 years: male, eczema and food/drug allergy were strongly associated, but for children >= 9 years old, obesity and aeroallergen sensitisation were strongly associated. For all children, higher socioeconomic deprivation was significantly associated with having an exacerbation. Delayed diagnosis was most common in children aged 5-8 years and was associated with increased exacerbations across all ages.ConclusionChildren's baseline characteristics and exacerbation rates varied according to their age group. Clinical guidelines should consider age at time of diagnosis more discretely than the broad range, 5-16 years, as this appears to impact on asthma severity and management.