Validation of a sensitive skin screening questionnaire in a Southeast Asian population

Sensitive skin syndrome (SSS) is common, but the lactic acid stinging test (LAST), a provocation-based reference procedure, is not always feasible in routine practice. This cross-sectional diagnostic accuracy study evaluated a brief trigger-based questionnaire against LAST in Vietnamese adult outpatients attending for health check-ups. A total of 198 participants completed a questionnaire including one self-identification item and 10 trigger items before undergoing LAST. The questionnaire showed acceptable discrimination for LAST positivity (area under the curve [AUC]=0.78; 95% confidence interval [CI]: 0.72-0.84). A post hoc cut-off of ≥3 triggers provided 68.9% sensitivity, 78.9% specificity, and 72.7% overall accuracy. LAST positivity was more frequent among women than men, and Fitzpatrick phototype distributions differed significantly between LAST groups. Self-reported sensitive skin, sun exposure, and cosmetic use were associated with LAST positivity in the multivariable analysis, although the estimates require caution because of imprecision and possible overfitting. This concise questionnaire may help identify adults likely to be LAST-positive in comparable outpatient settings. LAST positivity is not a definitive diagnosis of SSS, and external validation is required before broader use.