North Texas Research Forum 2025

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Division

North Texas

Hospital

Medical City Fort Worth

Specialty

Dermatology

Document Type

Poster

Publication Date

2025

Keywords

skin color, skin pigmentation, Fitzpatrick scale, individual typology angle, Fitzpatrick skin type

Disciplines

Dermatology | Medicine and Health Sciences | Skin and Connective Tissue Diseases

Abstract

Purpose The Fitzpatrick Scale (FS), originally developed to dose photochemotherapy in Caucasian skin, has become widely adopted for skin color categorization. It originally included types I-IV, with types V-VI added later for darker skin. The FS was designed for UV radiation reactivity assessment. However, it is increasingly used as a proxy for objective skin color classification, despite being based on a subjective questionnaire. Individual Typology Angle (ITA), a validated colorimetric measurement, presents a potential alternative. Previous studies examining these classification systems have been limited by small sample sizes and uneven distribution across skin tones with subjects predominantly having lighter skin tones. This study aims to explore these limitations by investigating the relationship between ITA measurements and Fitzpatrick Skin Types (FST) on a self-reported skin color survey in a cohort including the full spectrum of skin tones. Methods This study enrolled 440 subjects to evaluate relationships between subjective skin typing systems and objective colorimetric measurements. Participants completed a questionnaire covering self-reported skin color descriptors (very fair to very dark) and self-assessed Fitzpatrick type (I-VI). Objective colorimetric measurements were taken on the left inner arm using a colorimeter to minimize sun exposure influence. Individual Typology Angle (ITA) values were calculated from the measurements following established protocols. Statistical analysis was performed using pairwise comparisons with t-tests and pooled standard deviations to evaluate the relationships between ITA values and both subjective classification systems (p<0.05). Results Analysis showed that ITA angle was not statistically significant at predicting Fitzpatrick skin type (p=0.3528) and showed inconsistent predictability of perceived color descriptions (p=0.615). However, ITA angle demonstrated stronger association with self-described skin color compared to Fitzpatrick type (p<2.2e-16). Conclusion Our results reveal that Individual Typology Angle (ITA) measurements and Fitzpatrick Skin Types (FST) represent distinct and non-equivalent systems for skin categorization. While ITA provided more precise differentiation for self-reported skin color, it showed limitations in capturing full skin tone variation (p<2e-10). FST showed no significant differences between adjacent categories I-III (p=0.35286). These findings suggest current categorization options are insufficient, as shown by the lack of statistical significance between adjacent self-reported categories (Olive vs. Fair, p=0.381; Very Dark vs. Dark Brown, p=0.615). Our study indicates the FS's six choices inadequately represent skin color variation; future research should explore both objective measurements and expanded category ranges for improved clinical applications.

Original Publisher

HCA Healthcare Graduate Medical Education

Skin Color Cannot Be Confined to Six Categories: Comparing the Fitzpatrick Scale and Colorimetric Measures

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