title: Assessment of lifetime cumulative sun exposure using a self-administered questionnaire: reliability of two approaches.
abstract: Few studies have evaluated the reliability of lifetime sun exposure estimated from inquiring about the number of hours people spent outdoors in a given period on a typical weekday or weekend day (the time-based approach). Some investigations have suggested that women have a particularly difficult task in estimating time outdoors in adulthood due to their family and occupational roles. We hypothesized that people might gain additional memory cues and estimate lifetime hours spent outdoors more reliably if asked about time spent outdoors according to specific activities (an activity-based approach). Using self-administered, mailed questionnaires, test-retest responses to time-based and to activity-based approaches were evaluated in 124 volunteer radiologic technologist participants from the United States: 64 females and 60 males 48 to 80 years of age. Intraclass correlation coefficients (ICC) were used to evaluate the test-retest reliability of average number of hours spent outdoors in the summer estimated for each approach. We tested the differences between the two ICCs, corresponding to each approach, using a t test with the variance of the difference estimated by the jackknife method. During childhood and adolescence, the two approaches gave similar ICCs for average numbers of hours spent outdoors in the summer. By contrast, compared with the time-based approach, the activity-based approach showed significantly higher ICCs during adult ages (0.69 versus 0.43, P = 0.003) and over the lifetime (0.69 versus 0.52, P = 0.05); the higher ICCs for the activity-based questionnaire were primarily derived from the results for females. Research is needed to further improve the activity-based questionnaire approach for long-term sun exposure assessment.
authors.affiliation: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD 20892-7238, USA. yuchu@mail.nih.gov
authors.forename: Chu-Ling
authors.initials: CL
authors.lastname: Yu
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: D Michal
authors.initials: DM
authors.lastname: Freedman
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Fears
authors.forename: Richard
authors.initials: R
authors.lastname: Kwok
authors.forename: Gabriel
authors.initials: G
authors.lastname: Chodick
authors.forename: Bruce
authors.initials: B
authors.lastname: Alexander
authors.forename: Michael G
authors.initials: MG
authors.lastname: Kimlin
authors.forename: Anne
authors.initials: A
authors.lastname: Kricker
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Armstrong
authors.forename: Martha S
authors.initials: MS
authors.lastname: Linet
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D015203:Reproducibility of Results; D012650:Self Disclosure; D013472:Sunlight; D011795:Surveys and Questionnaires; D014481:United States