Environmental contact factors in eczema and the results of patch testing Chinese patients with a modified European standard series of allergens

Environmental contact factors in eczema were investigated in China by clinical questionnaire and patch testing patients with a modified European standard series of allergens. 217 consecutive eczema patients were studied. Contact dermatitis (CD) was clinically diagnosed in 30% of the patients. Among the patients patch tested, 46 patients had clinically diagnosed allergic CD (ACD), 20 patients clinically had non-ACD (NACD) (including 16 cases of irritant contact dermatitis, 1 case of phototoxic contact reaction and 3 cases of asteatotic eczema) and 115 patients had clinically suspected ACD. 45 patients (98%) in the ACD group went on to have relevant patch test results. The most common ACD was from metals, fragrance materials, cosmetics and rubber materials. The most common contact allergens identified were nickel, fragrance mix, para-phenylenediamine (PPD), carba mix and thimerosal. No adverse reactions were observed to patch testing, except for pruritus in patch-test-positive patients. The positive rate of patch testing in ACD was much higher than that in NACD (98% versus 15%, P < 0.05, chi(2)-test). 60 (28%) patients had facial dermatitis (FD). Among these, 20 (33%) were confirmed as having ACD. 48 (22%) patients had hand dermatitis (HD). Among these, 7 (15%) were confirmed as having ACD. Fewer patients were confirmed as having ACD in the HD group than in the FD (15% versus 33%, P < 0.05, chi(2)-test). Although the difference was not significant, the total positivity rate in the HD group (55%) was lower than in the other groups. 65 (30%) patients had unclassified endogenous eczema (UEE). The total positive rate of patch testing in the UEE group (56%) was no different from that in the FD or HD groups. However, the relevance of positive patch tests was hard to determine in UEE. These results indicate that CD is common in eczema; relatively more patients with FD have ACD, while other factors, such as irritation, may play more of a role in HD. The total positive rate of patch testing in the UEE group was no different from that in the FD or HD groups, suggesting that patch testing should be stressed in UEE and the relevance of positive patch test results in UEE should be studied further. It is effective and safe to patch eczema patients with a modified European standard series of allergens in China.