Use of CD63 expression as a marker of in vitro basophil activation and leukotriene determination in metamizol allergic patients


María L. Sanz Department of Allergology and Clinical Immunology University Clinic of Navarra Apartado 4209 31008 Pamplona Spain


Background: We assessed the reliability of basophil activation test (FAST) and sulphidoleukotriene production (CAST) in the in vitro diagnosis of allergy to metamizol, evaluating its sensitivity and specificity.

Methods: Twenty-six patients allergic to metamizol and 30 control individuals were studied. Skin tests with metamizol, FAST, and CAST were performed.

Results: FAST sensitivity was 42.3% and specificity 100%. The PPV of FAST is 100% and the NPV 99.4%. The likelihood ratio for a positive value cannot be calculated because the specificity is 100% and the likelihood ratio for a negative value is 0.58. CAST sensitivity was 52%, and specificity 90%. The PPV of the test is 5% and the NPV 99.5%. The likelihood ratio for a positive result was 5.2 and that for a negative result 0.53. FAST detects a larger number of cases when patients are studied within the first 6 months after the clinical reaction (χ = 4.2, P = 0.04) than later. Together with skin tests, FAST allowed detection of 69.2% patients allergic to metamizol, the same as CAST 76%. The joint use of the three techniques allowed identification of 76.9% of cases.

Conclusions: FAST and CAST are useful for the diagnosis of allergy to pyrazolones. Its usefulness clearly increases when recent reactions are studied.