TY - JOUR
T1 - Positivity ratio and reaction index
T2 - Patch-test quality-control metrics applied to the North American Contact Dermatitis Group database
AU - Warshaw, Erin M.
AU - Nelsen, David D.
AU - Sasseville, Denis
AU - Belsito, Donald V.
AU - Maibach, Howard I.
AU - Zug, Kathryn A.
AU - Fowler, Joseph F.
AU - Taylor, James S.
AU - DeLeo, Vincent A.
AU - Marks, James G.
AU - Storrs, Frances J.
AU - Mathias, C. G Toby
AU - Pratt, Melanie D.
AU - Rietschel, Robert L.
PY - 2010/4
Y1 - 2010/4
N2 - Background: The positivity ratio (PR) and reaction index (RI) characterize the ability of patch-test preparations to produce strong (++ or +++) reactions as opposed to weak (+), questionable, or irritant reactions. Objective: This study evaluates these measures for North American Contact Dermatitis Group (NACDG) patch-test preparations. Methods: The PR and RI were calculated for 79 NACDG standard allergens tested from 1994 to 2006 (n = 26,479 patients). The median values were used as cutoff values for "acceptable" versus "problematic" preparations. Results: The top 10 "acceptable" patch-test preparations (PR ≤ 55 and RI > 0.46) were mixed dialkyl thioureas 1% in petrolatum (pet), tixocortol-21-pivalate 1% pet, ethylenediamine dihydrochloride 1% pet, sesquiterpene lactone mix 0.1% pet, nickel sulfate 2.5% pet, bacitracin 20% pet, thimerosal 0.1% pet, epoxy resin 1% pet, colophony 20% pet, and mercaptobenzothiazole 1% pet. The most "problematic" patch-test preparations (PR > 55 and RI ≤ 0.46) were cocamidopropyl betaine 1% aqueous (aq), benzalkonium chloride 0.1% aq, jasmine absolute 2% pet, iodopropynyl butyl carbamate 0.1% pet, 2-bromo-2-nitropropane-1,3-diol 0.5% pet, methyldibromoglutaronitrile 0.4% pet, methyldibromoglutaronitrile/ phenoxyethanol 2% pet and 2.5% pet, dimethylol dihydroxyethyleneurea 4.5% aq, and clobetasol-17-propionate 1% pet. Conclusion: Caution should be used when interpreting reactions to "problematic" patch-test preparations with a high proportion of weak, irritant, and questionable reactions.
AB - Background: The positivity ratio (PR) and reaction index (RI) characterize the ability of patch-test preparations to produce strong (++ or +++) reactions as opposed to weak (+), questionable, or irritant reactions. Objective: This study evaluates these measures for North American Contact Dermatitis Group (NACDG) patch-test preparations. Methods: The PR and RI were calculated for 79 NACDG standard allergens tested from 1994 to 2006 (n = 26,479 patients). The median values were used as cutoff values for "acceptable" versus "problematic" preparations. Results: The top 10 "acceptable" patch-test preparations (PR ≤ 55 and RI > 0.46) were mixed dialkyl thioureas 1% in petrolatum (pet), tixocortol-21-pivalate 1% pet, ethylenediamine dihydrochloride 1% pet, sesquiterpene lactone mix 0.1% pet, nickel sulfate 2.5% pet, bacitracin 20% pet, thimerosal 0.1% pet, epoxy resin 1% pet, colophony 20% pet, and mercaptobenzothiazole 1% pet. The most "problematic" patch-test preparations (PR > 55 and RI ≤ 0.46) were cocamidopropyl betaine 1% aqueous (aq), benzalkonium chloride 0.1% aq, jasmine absolute 2% pet, iodopropynyl butyl carbamate 0.1% pet, 2-bromo-2-nitropropane-1,3-diol 0.5% pet, methyldibromoglutaronitrile 0.4% pet, methyldibromoglutaronitrile/ phenoxyethanol 2% pet and 2.5% pet, dimethylol dihydroxyethyleneurea 4.5% aq, and clobetasol-17-propionate 1% pet. Conclusion: Caution should be used when interpreting reactions to "problematic" patch-test preparations with a high proportion of weak, irritant, and questionable reactions.
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U2 - 10.2310/6620.2010.09092
DO - 10.2310/6620.2010.09092
M3 - Article
C2 - 20233547
AN - SCOPUS:77949592500
SN - 1710-3568
VL - 21
SP - 91
EP - 97
JO - Dermatitis
JF - Dermatitis
IS - 2
ER -