Background: The evolution of mite sensitisation profiles from childhood to adulthood is associated with distinct clinical outcomes. Longitudinal sensitisation trajectories have never been addressed across two generations over an extended time frame. Using molecular diagnosis, we aimed to investigate how the evolution of mite sensitisation relates to the expression of rhinitis and asthma in adult versus paediatric patients over a 20-year period. Methods: Specific IgE (sIgE) to mite molecular allergens was determined using MeDALL allergen chip (Der p 1, 2, 4, 5, 7, 10, 11, 14, 15, clone 16, 18, 21 and 23; Der f 1, Der f 2, Lep d 2, Blot t 5). Assessment was made in adult (n=21), adolescent (n=11) and paediatric patients (n=19) with rhinitis and/or asthma, in T1 (20-years-ago) and in T2 (current time). Results: After the 20-year-period, the adult cohort significantly decreased the number of sIgE responses to mite components - T1: 7 [3-9] versus T2: 4 [2-6], median [IQR], p=0.0040. A strong negative correlation was observed between age and the 20-year variation of sensitisation count (r = - 0.5305; p<0.0001). In adults, the reduction in mite molecular IgE responses was associated with improvement in rhinitis (p=0.0010) and asthma (p=0.0020), reflecting disease progression patterns not observed in the paediatric cohort. Conclusions: This is the first analysis to show that molecular mite sensitisation declines with ageing, and this reduction may relate to decreased asthma and rhinitis symptoms and severity. This age-associated decline highlights the importance of careful clinical interpretation in older adults to avoid overtreatment and missed diagnoses.

Background: The evolution of mite sensitisation profiles from childhood to adulthood is associated with distinct clinical outcomes. Longitudinal sensitisation trajectories have never been addressed across two generations over an extended time frame. Using molecular diagnosis, we aimed to investigate how the evolution of mite sensitisation relates to the expression of rhinitis and asthma in adult versus paediatric patients over a 20-year period. Methods: Specific IgE (sIgE) to mite molecular allergens was determined using MeDALL allergen chip (Der p 1, 2, 4, 5, 7, 10, 11, 14, 15, clone 16, 18, 21 and 23; Der f 1, Der f 2, Lep d 2, Blot t 5). Assessment was made in adult (n=21), adolescent (n=11) and paediatric patients (n=19) with rhinitis and/or asthma, in T1 (20-years-ago) and in T2 (current time). Results: After the 20-year-period, the adult cohort significantly decreased the number of sIgE responses to mite components - T1: 7 [3-9] versus T2: 4 [2-6], median [IQR], p=0.0040. A strong negative correlation was observed between age and the 20-year variation of sensitisation count (r = - 0.5305; p<0.0001). In adults, the reduction in mite molecular IgE responses was associated with improvement in rhinitis (p=0.0010) and asthma (p=0.0020), reflecting disease progression patterns not observed in the paediatric cohort. Conclusions: This is the first analysis to show that molecular mite sensitisation declines with ageing, and this reduction may relate to decreased asthma and rhinitis symptoms and severity. This age-associated decline highlights the importance of careful clinical interpretation in older adults to avoid overtreatment and missed diagnoses.