1. BACKGROUND AND RATIONALE:
We extended the pilot study (IRB STU27549) of our objective measurement of skin pigmentation with correlation to the self-reported skin reaction to sun exposure to a larger sample with special emphasis on people with skin of color and compare the results to those obtained by spectrophotometry. We found that forty-two percent (114 of 270) of the participants' responses to the burning and tanning questions could not be classified using standard Fitzpatrick skin phototype (FST) definitions. At present, we seek to determine the accuracy of an adapted Skin Sun Sensitivity Scale for individuals of all pigmentation varieties (FST I through VI) as compared with spectrophotometric measurements assessing FST.
Fitzpatrick Skin Phototyping Skin phototyping has usually been determined subjectively by trained investigators or clinicians using sun burning and/or sun tanning responses. In addition, subject self-report of ease of sunburning and tanning is used in surveys to determine the risk of developing skin cancer. (Table 1) Responses to the Fitzpatrick Skin Phototype (SPT) questions may be unreliable due to recall bias, subjective bias by clinicians and subjects, lack of cultural sensitivity of the questions, and the subjects' use of sun protection behaviors from early childhood such that the subject may not have experienced sunburn.
Table 1. Skin type; Erythema and Tanning Reactions to the First Summer Exposure I Always burns, never tan (painful burn at 24 hrs and no tan at 7d) II Burn easy, then develop light tan (painful burn at 24 hrs and a light tan at 7d) III Burn moderately, then develop light tan (slightly tender burn at 24 hrs, moderate tan at 7d) IV Burn minimally-rarely, then develop moderate tan (no burn at 24 hrs and a good tan at 7d) V Never burns, always develops dark tan VI Never burns, no noticeable change in appearance
Unreliable Sunburning History A limitation of the 6 integer Roman numeral Fitzpatrick SPT was reliance upon a history of sunburn after the first exposure of the summer. For those who reside in regions that have sun exposure all year (e.g. Arizona, Florida, California), the sunburning-tanning question after the first exposure of the summer was often irrelevant. Lastly, in the 1990s people began to use sunscreens to prevent sunburns, thus, those with sun sensitive skin may never have experienced sunburn and were unable to answer the question about ease of sun burning.
Multi-ethnic Populations There has been a tendency to group all people of a similar ethnic group into a single category of SPT, which introduces potential bias into the subjective assessment of SPT by investigators. For example, Hispanic whites are often considered "brown" and assigned to Skin Type IV (Table 2). The heterogeneity of those with multi-ethnic backgrounds makes it difficult to assess susceptibility to skin cancer on the basis of skin color, which is predominantly determined by pigments such as hemoglobin, melanin, bilirubin, and carotene.
Skin Phototyping by Sunburning Ability. Skin Phototype Appearance Sunburning ability I Very white or freckled Always burn II White Usually burn III White to Olive Sometimes burn IV Brown Rarely burn V Dark brown Very rarely burn VI Black Never burn
Over the last 3 decades, the Fitzpatrick SPT evolved from its original purpose of determining the amount of ultraviolet light (UVL) for treatment of psoriasis patients living in New England to become an assessment tool for skin cancer risk. As part of this evolution, the original 4 skin types (I-IV), that assessed sun reactivity with standardized questions about the ease of sun burning and tanning reactions to the first summer sun exposure, were modified by adding SPT V and VI to include those with brown and black skin.
Our research demonstrated that the SPT modifications to include people with skin of color were neither culturally sensitive nor accurate as people of color were unable to respond to the questions about their experience with sunburn and tanning. People with skin of color did not report becoming red or pink but rather experienced "irritation" after sun exposure. In our recently reported work, we proposed a modification of the FST questions to allow people with skin of color to be able to respond (Survey questions 1and 2). We now wish to test the responses of people to these self-report questions and compare the responses with the melanin index as determined by spectrophotometry.(Survey question 9)
Spectrophotometry The "gold standard" method of assessing skin pigmentation is reflectance spectrophotometry (RS). Pershing et al performed seminal research comparing the area under the curve obtained by RS to profile the constitutive skin color with clinicians' assessment of SPT. For skin types I-III, Pershing et al (2008) found inconsistency between clinicians' and reflectance spectrophotometric (RS) assessments of SPT. The clinicians adjusted the patients' SPT as determined by their historical sun burning and tanning response by factoring in observed hair and eye color. For example, red-haired individuals determined by RS to be SPT III were listed as SPT I by clinical dermatologists. Subjective assessment of SPT by clinicians was heavily influenced by patients' hair and eye color. The Pershing study, which accrued 125 subjects did not accrue sufficient numbers of subjects with skin of color (Skin types III-VI) to be able to report meaningful results. (I 20; II 53, III 21, IV 10, V 16, VI 5)
It should be noted that the area under the curve obtained by RS includes the red reflectance, thus, it is does not solely represent skin pigmentation. Skin pigmentation or melanin provides photoprotection and can be calculated as melanin index, MI. (see following section on Melanin Index) Even as early as 1961, the potential for confounding of the MI obtained by RS by dilatation of superficial blood vessels was recognized. The device, Mexameter MX 18, internally corrects for the red reflectance in calculating the melanin index. The melanin index is derived from the multilayered skin model and Lambert-Beer's law.
Significance:
While those that are at risk to develop skin cancer have less melanin content (skin type I) than those at low risk (skin type VI), people with skin phototypes in the mid-range (III and IV) believe that their natural skin tone is protective against sunburns, thus, they fail to use sun protection. When people with skin type III and IV are exposed to more intense ultraviolet light in more southern latitudes than Chicago they are surprised by the sunburn they experience. In our proof of principle research, people with skin type III and IV, who viewed the image of their skin on the computer screen, perceived that the "color was grainy" and made the conclusion that the "holes" in their skin pigment made it possible for them to burn
This study will further objectively measure the MI of people with skin of color. Thus, it is essential that we accrue a representative sample of people with skin of color with all ethnic groups represented over the greatest range of skin types for those self-identifying themselves as members of the group.
2. STUDY OBJECTIVES:
Our principal objective is to correlate the melanin index under usual conditions by spectrophotometry with the adapted Fitzpatrick SPT as determined by the patients' responses to the adapted questionnaire.
