Are the Fitzpatrick skin phototypes valid for cancer risk assessment in a racially and ethnically diverse sample of women?

The Fitzpatrick Skin Phototypes (FSP) were developed to classify skin color and response to ultraviolet radiation. FSP are used clinically to assess risk for sunburn and skin cancer. Our aim was to determine the criterion-related validity of self-reported FSP when compared with skin color and sunburn history, controlling for age, race/ ethnicity, and seasonality/geography. We performed a secondary analysis of data (N=466) from an observational study. The racial/ethnic composition of the sample was 45% White/White Hispanic (WWH), 40% Black/Black Hispanic (BBH), and 15% Other Identities. Outcome measures were self-reported FSP and sunburn history, as well as physiological measures of skin color (L* lightness/darkness, a* redness/greenness, b* yellowness/blueness). Correlation between FSP and L* was -.77 (95% CI -.81, -.73; P<.001). Although 60% of the variance in FSP was accounted for by L* values for the entire sample, only 5% of the variance was accounted for among BBH participants (r=-.23), and up to 30% for WWH/Other Identity participants (r=-.48 and -.52). Multiple regression analysis indicated L* and b* values, sunburn history, and race/ethnicity, but not geography/seasonality or a* values significantly and collectively accounted for 72% of the variance in FSP. While the criterion validity of FSP was established by the strong relationship between L* values and FSP for the entire sample, when examined at the level of individual racial/ethnic subgroups, criterion validity of FSP was not demonstrated. When self-reported FSP are used for clinical skin assessment and sun cancer screening, they provide a restricted range of options for people with darker skin that does not capture variations in their skin color. Inaccuracy of clinical data may lead to unequal treatment or inadequate cancer risk assessment.