THE HISTAMINE SKIN TEST

Abstract

I their paper entitled "Methodological Considerations in the Histamine Skin Test" (Joubert and Thomas, J. Clin. Pharm. 10 :165, 1970) the authors present and comment on a number of methodological considerations in a most sophisticated technical and statistical fashion. It is therefore singularly remarkable that they totally ignore variations introduced by the simple method of testing in a purely mechanical fashion. They state "an aqueous solution of histamine containing 0.005 mg in 0.05 ml was injected intradermally with disposable tuberculin syringes" but nowhere examine or discuss the accuracy or reproducibility of this procedure. It is quite clear from a number of published studies that there is wide variability in the "intradermality" of such injections, in the volume delivered biologically to some site in the skin, in the volume dispensed by disposable tuberculin syringes, in the calibration (volumetric scale) of such syringes, in the mechanical ability to control volume delivery from such syringes, and in the amount of 'leakage' or 'waste' during injections. It should be clear that the sum of such variables may lead to test variability which is of at least equal significance to some of the more sophisticated sources of variation considered by the authors and may be a limiting factor on the interpretability of results.