Evaluation of High Speed Laser Doppler Imaging Technology to Measure Skin Prick Tests in Daily Allergologic Practice

Abstract

RATIONALE: Skin prick tests (SPT) are commonly used in daily allergologic practice to evaluate skin reactivity to various allergens. The current visual evaluation of SPT is observer dependent. To evaluate an objective measurement of skin reactivity to SPT, we compared the classical visual reading (CVR) with a method of high speed laser Doppler imaging (HS-LDI). METHODS: First, SPT, including positive and negative controls, birch and grass pollen extracts (Stallergenes, France) were applied to 20 volunteers (10 atopics, 10 non atopics) to determine tests characteristics (cut-off, optimal reading time and allergen concentration). Then 20 atopic patients were tested, with optimal allergen concentration and time window, with birch and grass pollen extracts and skin reactivity was measured with CVR and HS-LDI. RESULTS: The optimal concentration was 1/1 whereas the optimal time window for the lecture of SPT with HS-LDI was 5-10 min. for histamine and 10-15 min. for allergens. The sensitivity of CVR was 93% and of HS-LDI 100%, whereas the specificity of CVR was 94% and of HS-LDI 82%. CONCLUSIONS: The lecture of SPT with HS-LDI proved to be a simple and more sensitive but less specific method than CVR. Its future application could be the lecture of SPT in patients showing doubtful results with CVR and in clinical trials where an objective method of reading of SPT is needed.