Comparison of a new lancet and a hypodermic needle for skin prick testing

Skin prick tests with a standard allergen panel were carried out in duplicate (one on each arm) on all patients referred to an allergy out-patient clinic. A new lancet with 1-mm point length and a disposable hypodermic needle were used. Patients were randomized to lancet-needle, lancet-lancet, or needle-needle, and the skin prick tests were done by experienced or inexperienced nurses. The mean of the biggest and smallest diameters was used as a measure of the size of the wheal. Skin reactions from a total of 142 patients were included. For both lancet and needle a significant difference was noted when comparing experienced versus inexperienced investigators' reproducibility expressed as coefficient of variation. There was no significant difference in reproducibility when comparing lancet and needle results, and no significant difference in wheal size when comparing with histamine references. Surprisingly, the reactions on left arms were generally larger than those on right arms.