Skin prick test is equal to gold standard in identification of house dust mite sensitisation

Background: Allergens are known trigger factors for exacerbations of atopic dermatitis (AD). Skin prick test (SPT) and serum specific IgE (SSIgE) test are standard diagnostic tools to establish allergen sensitivities. Comparatively, SSIgE is costly, needs special laboratory facilities, involves taking serum samples (difficult in children) and it takes time to get reports. SPT is relatively inexpensive and results are available immediately.
Objectives: To compare the results of SPT and SSIgE to detect allergen sensitivity in paediatric patients with AD.  
Method: Patients with AD were recruited from specialised dermatology clinics at Sirimavo Bandaranayake Specialised Children’s Hospital and National Hospital Kandy, Sri Lanka from June 2019 to March 2020. Sensitization to house dust mite (HDM) species Dermatophagoids Pteronyssinus (HDM-DP), cat epithelia (CE), cow’s milk (CM), egg white (EW), Aspergillus fumigatus (AF) was checked using SPT and SSIgE. SSIgE assessed with Immunocap method, >15 kU/L was taken as positive. In SPT, a wheal =3mm than the negative control was taken as positive.
Results: Fifty-two patients were involved in the study. HDM-DP was positive in 51.9% with SPT while 50% were positive with SSIgE; 15.4% tested positive for CE with both SPT and SSIgE. There was a highly significant correlation between SPT and SSIgE for HDM (p<0.001). A significant correlation was also seen for CE (p=0.011). AF, CM, and EW did not show a significant correlation.
Conclusions: SPT and SSIgE showed significant correlation in relation to HDM and CE sensitivity.