title: Effects of smartphone diaries and personal dosimeters on behavior in a randomized study of methods to document sunlight exposure.
abstract: Dosimeters and diaries have previously been used to evaluate sun-related behavior and UV exposure in local samples. However, wearing a dosimeter or filling in a diary may cause a behavioral change. The aim of this study was to examine possible confounding factors for a questionnaire validation study. We examined the effects of wearing dosimeters and filling out diaries, measurement period and recall effect on the sun-related behavior in Denmark in 2012. Our sample included 240 participants eligible by smartphone status and who took a vacation during weeks 26-32 in 2012, randomized by gender, age, education and skin type to six groups: 1) Control + diary, 2) Control, 3) 1-week dosimetry measurement, 4) 1-week dosimetry measurement + diary, 5) 3-week dosimetry measurement and 6) 1-week dosimetry measurement with 4 week delayed questionnaire. Correlation coefficients between reported outdoor time and registered outdoor time for groups 3-6 were 0.39, 0.45, 0.43 and 0.09, respectively. Group 6 was the only group not significantly correlated. Questionnaire reported outdoor exposure time was shorter in the dosimeter measurement groups (3-6) than in their respective controls. We showed that using a dosimeter or keeping a diary seems to increase attention towards the behavior examined and therefore may influence this behavior. Receiving the questionnaire with 4 week delay had a significant negative influence on correlation and recall of sunburn. When planning future UV behavior questionnaire validations, we suggest to use a 1-week interval for dosimetry measurements, no diary, and to minimize the time from end of measurement to filling out questionnaires.
authors.affiliation: Department of Prevention and Information, Danish Cancer Society, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark; Research Unit of General Practice, University of Southern, Denmark.
authors.forename: Brian
authors.initials: B
authors.lastname: Køster
authors.affiliation: Research Unit of General Practice, University of Southern, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Søndergaard
authors.affiliation: Research Unit of General Practice, University of Southern, Denmark.
authors.forename: Jesper Bo
authors.initials: JB
authors.lastname: Nielsen
authors.affiliation: Electrical and Computer Engineering, University of Canterbury, New Zealand.
authors.forename: Martin
authors.initials: M
authors.lastname: Allen
authors.affiliation: Department of Prevention and Information, Danish Cancer Society, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Bjerregaard
authors.affiliation: Research Centre, Danish Cancer Society, Denmark.
authors.forename: Anja
authors.initials: A
authors.lastname: Olsen
authors.affiliation: Department of Prevention and Information, Danish Cancer Society, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark.
authors.forename: Joan
authors.initials: J
authors.lastname: Bentzen
keywords: Personal UV dosimetry; Prevention; Questionnaire; Skin cancer; Smartphone; Ultraviolet radiation