Phototype reproducibility and relation to objectively measured skin sensitivity is best when burn and tan reactivity to sun are answered separately

摘要

Background/purpose: Skin phototype questionnaires usually ask similar questions, but they differ in how the answers can be given. There is either one combined answer, which includes both tendency to burn and ability to tan, or 2 separate answers about burn and tan, respectively. We tested the reproducibility of different questionnaires and their relation to objectively measured skin phototype.Method: A total of 149 participants completed 3 skin phototype questionnaires distributed twice with median 3 months interval: (i) a Fitzpatrick questionnaire (FST-q) with combined answers about tendency to burn and ability to tan, (ii) a detailed questionnaire (Detail-q) with separate answers to 2 detailed questions about burn and tan and (iii) a short questionnaire {Short-q) with separate answers to 2 simplified questions about burn and tan. Objective skin phototype measurements were performed by measuring pigment protection factor (PPF) by spectrophotometry. Results: Good-to-very-good reproducibility for all phototype questionnaires was shown by weighted kappa (k_w) values: k_w = .65 for the FST-q with combined (burn and tan) answers; k_w = .64 for tendency to burn and k_w = .68 for ability to tan for the Detaii-q; and k_w = .72 for tendency to burn and k_w = .85 for ability to tan for the Short-q. PPF at all measurement sites was best predicted by the Detaii-q (highest r~2 = 0.285 on the outer arm), followed by the Short-q and by the FST-q. Conclusion: The detailed questionnaire with separate answers to 2 detailed questions about tendency to burn and ability to tan has good reproducibility, correlates best with objective skin measurements and is therefore the recommended method for determining skin phototype.