title: Estimation of individual cumulative ultraviolet exposure using a geographically-adjusted, openly-accessible tool.
abstract: BACKGROUND
  Estimates of an individual's cumulative ultraviolet (UV) radiation exposure can be useful since ultraviolet radiation exposure increases skin cancer risk, but a comprehensive tool that is practical for use in the clinic does not currently exist. The objective of this study is to develop a geographically-adjusted tool to systematically estimate an individual's self-reported cumulative UV radiation exposure, investigate the association of these estimates with skin cancer diagnosis, and assess test reliability.
  
  
  METHODS
  A 12-item online questionnaire from validated survey items for UV exposure and skin cancer was administered to online volunteers across the United States and results cross-referenced with UV radiation indices. Cumulative UV exposure scores (CUES) were calculated and correlated with personal history of skin cancer in a case-control design. Reliability was assessed in a separate convenience sample.
  
  
  RESULTS
  1,118 responses were included in the overall sample; the mean age of respondents was 46 (standard deviation 15, range 18 - 81) and 150 (13 %) reported a history of skin cancer. In bivariate analysis of 1:2 age-matched cases (n = 149) and controls (n = 298), skin cancer cases were associated with (1) greater CUES prior to first skin cancer diagnosis than controls without skin cancer history (242,074 vs. 205,379, p = 0.003) and (2) less engagement in UV protective behaviors (p < 0.01). In a multivariate analysis of age-matched data, individuals with CUES in the lowest quartile were less likely to develop skin cancer compared to those in the highest quartile. In reliability testing among 19 volunteers, the 2-week intra-class correlation coefficient for CUES was 0.94. We have provided the programming code for this tool as well as the tool itself via open access.
  
  
  CONCLUSIONS
  CUES is a useable and comprehensive tool to better estimate lifetime ultraviolet exposure, so that individuals with higher levels of exposure may be identified for counseling on photo-protective measures.
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, 450 Broadway St., Redwood City, CA, 94063, USA. gefeizhu@stanford.edu.
authors.forename: Gefei A
authors.initials: GA
authors.lastname: Zhu
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, 450 Broadway St., Redwood City, CA, 94063, USA. iraber@stanford.edu.
authors.forename: Inbar
authors.initials: I
authors.lastname: Raber
authors.affiliation: Department of Computer Science, 353 Serra Mall, Stanford, CA, 94305, USA. sukolsak@stanford.edu.
authors.forename: Sukolsak
authors.initials: S
authors.lastname: Sakshuwong
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, 450 Broadway St., Redwood City, CA, 94063, USA. shufeng@stanford.edu.
authors.forename: Shufeng
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, 450 Broadway St., Redwood City, CA, 94063, USA. asli@stanford.edu.
authors.forename: Angela S
authors.initials: AS
authors.lastname: Li
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, 450 Broadway St., Redwood City, CA, 94063, USA. cztan@stanford.edu.
authors.forename: Caroline
authors.initials: C
authors.lastname: Tan
authors.affiliation: Department of Dermatology, Stanford University School of Medicine, 450 Broadway St., Redwood City, CA, 94063, USA. alschang@stanford.edu.
authors.forename: Anne Lynn S
authors.initials: AL
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D000069079:Radiation Exposure; D012044:Regression Analysis; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012878:Skin Neoplasms / Q000453:epidemiology / Q000209:etiology*; D011795:Surveys and Questionnaires; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014481:United States / Q000453:epidemiology; D055815:Young Adult