[Comparison of 4 skin prick tests to detect immediate hypersensitivity]

To diagnostic allergic diseases it's necessary an adequate history, and in vivo or in vitro test, to determine specific IgE. The skin prick test are the best for this, because are more sensitive, economic and quick to do. However there are variability in results with the different instruments to do it (the Morrow-Brown (MB), needle, Prick lancet (L)t Multi-Test (MT), and the Doutip-Test). To consider this instruments how adequate diagnostic proceedings, we should evaluate some characteristics. Because it, our objective was to evaluate precision, sensitivity, specificity and patient preference by each one.

Prospective study in 20 patients with asthma or allergic rhinitis who comes to the allergy service of Hospital Infantil de México Federico Gómez. We analyzed skin prick test with DT, MB, MT and L on the back surface with histamine in five times and glicerosaline in one. We measured wheel and flare diameters 15 minutes after applications. We consider positive results if medium diameter of wheel was 3 mm or flare 10 mm. Precision was measured by coefficient of variation of wheel with histamine with each instrument. Patient preference was considered in relation to low grade of discomfort with each one. Precision was compared by two- vias varianza analysis. No parametric Friedman test was used to compared patient preference.

We studied 20 patients, 40% was females and 60% males. The ages were 10 to 16 years old Promedio wheal histamine diameter was to MB = 5.1 +/- 1.1, L = 6.1 +/- 0.8, DT = 6.7 +/- 0.9, MT = 6.3 +/- 1.5; promedio flare diameter with histamine was to MB: 15.9 +/- 4.2, L: 19.0 +/- 4.8, DT = 21.9 +/- 4.8, MT = 18 +/- 6.9. Sensibility of DT was 100%, L = 99%, MT = 97% and MB 95%. The specificity of MB was 90%, L = 70%, MT = 41.6% and DT 30%. DT coefficient of variation was 15.6%, L: 17.3%, MT = 24.4% and MB 24.6%.

In our study more sensitive device was DT, more specific was MB and more precise was DT. Patients preferred the lancet, because they had less discomfort when used it.