title: Questionnaire items to assess skin color and erythemal sensitivity: reliability, validity, and "the dark shift".
abstract: BACKGROUND
  Skin pigmentation is a key factor for UV radiation exposure related cancers. To appropriately target cancer control activities related to this exposure and for better representation in epidemiologic studies, a valid and reliable assessment of skin color is required.
  
  
  METHODS
  The validity and reliability of two self-report measures were assessed: skin color and erythemal sensitivity. A sample of 289 university students categorized their unexposed skin color and photosensitivity via a questionnaire. Skin color was also measured by spectrophotometer. After 7 days, participants repeated the self-report assessment.
  
  
  RESULTS
  Significant correlations were found for both self-report items with objective measures, indicating that these items may be valid assessment tools (color: Spearman's rho=-0.75, P<0.001; photosensitivity: Spearman's rho=-0.64, P<0.001). No sex differences in validity were evident. Stronger correlations were found among those of European than those of non-European ethnicity (color: Spearman's rho=-0.78 versus -0.59, bootstrap P=0.007; photosensitivity: Spearman's rho=-0.63 versus -0.28, bootstrap P=0.001). Strong biases toward overestimation of skin pigmentation were evident, ranging from 36% in the self-identified fair skin group to 77% in the medium skin color group. Intrarater reliability of the questionnaire items was high (color: k=0.78, P<0.001; photosensitivity: k=0.77, P<0.001).
  
  
  CONCLUSIONS
  Study findings suggest that self-report may be a valid measurement strategy when assessing skin type, but there is a bias toward overestimation of skin color and, potentially, UV radiation resilience.
  
  
  CONCLUSIONS
  This bias has the potential to undermine the effectiveness of skin cancer prevention efforts and needs to be addressed in health promotion programs.
authors.affiliation: Cancer Society of New Zealand Social & Behavioural Research Unit, Department of Preventive & Social Medicine, Dunedin School of Medicine, University of Otago, P.O. Box 913, Dunedin 9054, New Zealand. tony.reeder@otago.ac.nz
authors.forename: Anthony I
authors.initials: AI
authors.lastname: Reeder
authors.forename: Vanessa A
authors.initials: VA
authors.lastname: Hammond
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Gray
mesh_terms: D000293:Adolescent; D000328:Adult; D004890:Erythema / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010787:Photosensitivity Disorders / Q000175:diagnosis* / Q000209:etiology; D015203:Reproducibility of Results; D012867:Skin / Q000528:radiation effects; D012880:Skin Pigmentation; D013472:Sunlight / Q000009:adverse effects; D011795:Surveys and Questionnaires; D055815:Young Adult