Patterns and risk factors of causative contact allergens in Thai adult patients with contact dermatitis

BACKGROUND Surveillance on common allergens identified by patch testing plays an important role in emerging allergen detection, which leads to both individual and societal level prevention. OBJECTIVE To study the changes in the pattern of contact sensitization and to identify risk factors associated with allergens. METHOD The data of 206 patients who underwent patch testing at King Chulalongkorn Memorial Hospital during 2012 to 2015 were assessed. The associations between patient risk factors and positive reactions to each allergen were evaluated. The results were compared with data from 2003-2004. RESULTS The top five most common allergens during 2012-2015 were nickel sulfate (19.4%), methylchloroisothiazolinone/ methylisothiazolinone (MCI/MI) (13.6%), fragrance mix I (FM I) (10.7%), carba mix (9.2%) and cobalt chloride (6.3%) whereas, during 2003-2004, these were nickel sulfate, cobalt chloride, FM I, potassium dichromate and Myroxylon pereirae. A positive patch test to nickel was strongly associated with a history of metal and seafood allergy (p<0.001; OR, 4.94; 95% CI = 2.33-10.47 and p=0.028; OR, 2.55; 95% CI, 1.11-5.85, respectively). MCI/MI was correlated with a history of personal care products allergy, and fragrance was correlated with a history of urticaria (p=0.005; OR, 4.05; 95% CI = 1.54-10.66 and p=0.031; OR, 2.71; 95% CI, 1.10-6.68, respectively). CONCLUSIONS There was an alteration in the pattern of contact sensitization detected by our standard series. MCI/MI has become the most common preservative causing contact allergy.