Analysis Of Patch Test: A Retrospective Study Of 178 Patients With Suspected Contact Dermatitis

Objective To identify the common allergens of suspected contact dermatitis. Further more, we tried to investigate the possible association between allergens and clinical features.Methods In this retrospective research, patch test results of 178 patients who were clinically suspected of allergic contact dermatitis, referred to our clinic between Jan. 2004 and Feb. 2007, were evaluated. All the patients were patch tested with Rui-min standant series patch-test kit. The patients selected did not neither be treated with topical or systemic corticosteroids for at least 15days, nor immunoregulant for at least 7days, nor antihistamine for at least 3days and did not have the history of burnt for at least 4 weeks. The patients diagnosed as dermatitis seborrheica, atopic dermatitis, primary irritant contact dermatitis and factitious urticaria were excluded. The positive rates of the allergens were studied within different groups divided according to different genders, affected parts of suspect contact dermatitis and the age of patients. Data were stored and assessed using SPSS 12.0. The X~2 was used for the comparisons. A one-tailed p-value less than 0.05 was taken to indicate a statistically significant association.Results The whole positive rate of the contact allergens was 84.4%. The first 5 contact allergens were potassium dichromate (30.9%), nickel salfate (30.3%), fragrance mix (19.1%), formaldehyde (15.7%) and thiomersalate (11.8%). The moderate positive reactions were most frequently caused by nickel salfate (17.9%). Compared with the females, positive reaction to carba mix and paraphenylenediamine causing the lesion were more frequently in the male with statistically significant diference. The positive rates of patch tests of each allergen were compared among the hand, face and trunk and limbs, the results showed that there were no statistically significant diference among different body sites. Compared with patients older than 40 years, positive reactions to nickel sulfate were more frequently in the younger group.Conclusions Nickel potassimn, dickromate sulfate, nickel salfate, fragrance mix, formaldehyde and thiomersalate are the main allergens causing allergic contact dermatitis. Positive reactions to carba mix and paraphenylenediamine were more frequently in males than in females. Positive reactions to nickel sulfate were more frequently in the younger group(<40 years).