Patch testing with corticosteroid mixes in Europe. A multicentre study of the EECDRG

This study investigated whether a corticosteroid mix containing tixocortol pivalate, budesonide, and hydrocortisone-17-butyrate could detect contact allergy to corticosteroids. 2 corticosteroid mixes, 1 with a high (mix I) and 1 with a low (mix II) concentration and the 3 individual constituents; each at 2 concentrations, were inserted into the standard series of 16 participating clinics. Tests were read on day (D) 3 or 4. 5432 patients were tested, and 110 (2.0) had positive reactions to at least 1 of the 8 test preparations. Of the 8 preparations, mix I identified most allergic patients, followed by mix II, budesonide 0.10, budesonide 0.002, and tixocortol pivalate, both concentrations (1.0 and 0.10) tracing the same number. With the mixes, 53.2-59.6 of tixocortol pivalate allergy was missed. 47 patients were allergic to either concentration of tixocortol pivalate, 25 of these only to 1.0 and another 25 only to 0.10. Testing with mix I and tixocortol pivalate 0.10 picked up 98/110, testing with tixocortol pivalate 1.0 and 0.10 and budesonide 0.10 picked up 105/110. 3379 patients were read on both D3 or D4 as well as on D7. Without a late reading (D7), up to 30 of contact allergy to corticosteroid markers was missed.