Skin prick testing using allergen-coated lancets: a comparison between a multiple lancet device and a single lancet applied with varying pressures


Mr S. B. Phagoo, Department of Paediatrics and Neonalal Medicine. Royal Postgraduate Medical School, Hammersmith Hospital, Du Cane Road, London W12 0NN.


Allergen-coated lancets have been developed to simplify skin prick testing. The effect of variation in application pressure on the response to prick tests was assessed in 20 alopic subjects, and the results compared to the response obtained with a newly devised multiple lancet device (M LD), capable of holding up to eight lancets and of providing a standardized application pressure. A positive weal (geqslant R: gt-or-equal, slanted 7 mm2) using light pressure occurred in 2/20 subjects, compared with 14/20 after moderate pressure. The largest weals were obtained using hard pressure and with the MLD (all 20 subjects obtained positive weals) and there was no significant difference in weal si/e between the two. There was evidence of a late reaction in 4/17 subjects with the MLD and with hard pressure applied to a single lancet, but in only one with moderate and in none with light pressure. Thus both the early and late skin responses are dependent on the pressure applied. The newly designed MLD allows skin prick tests to be performed using a standard pressure. It is also convenient for multiple allergen testing of uncooperative children.