[ANALYSIS OF PATCH TEST RESULTS USING COCAMIDOPROPYL BETAINE-RELATED SURFACTANTS]

A few previous studies have compared the patch test (PT) results obtained using different types of PT units.

This study aimed to compare PT results between the Patch Tester 'Torii' and Finn Chamber.

Thirty-four patients with intractable scalp dermatitis were enrolled in this study. PT were performed with three kinds of amphoteric surfactants, cocamidopropyl betaine (CAPB), high-concentration CAPB (h-CAPB), and lauramidopropyl betaine (LAPB), using both the Patch Tester 'Torii' and Finn Chamber, and the changes in the subjects' symptoms after they stopped using these surfactants were examined.

Regarding the PT results for CAPB, h-CAPB, and LAPB, the results obtained with the Finn Chamber included a significantly lower frequency of irritant reactions (CAPB; p=0.003, h-CAPB; p=0.046, LAPB; p=0.002) than those obtained with the Patch Tester 'Torii'. However, there were no significant differences in the frequencies of positive reactions between the Patch Tester 'Torii' and Finn Chamber in each surfactant. The same tendency was seen in PT with LAPB (p=0.041) in 17 selected patients, who showed positive or doubtful reactions in PT performed with the surfactant-containing products they had used and whose symptoms 'markedly improved' or 'improved' after they stopped using these products. Among these surfactants, CAPB exhibited the highest positivity rate; however, the differences were not significant.

In patients with intractable scalp dermatitis, PT of the abovementioned surfactants performed using the Finn Chamber were superior to those conducted using the Patch Tester 'Torii' because they resulted in fewer irritant reactions.