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Association of Increased Sun Exposure Over the Life‐course with a Reduced Risk of Juvenile Idiopathic Arthritis
Author(s) -
ChiaroniClarke Rachel C.,
Munro Jane E.,
Pezic Angela,
Cobb Joanna E.,
Akikusa Jonathan D.,
Allen Roger C.,
Dwyer Terence,
Ponsonby AnneLouise,
Ellis Justine A.
Publication year - 2018
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.13045
Subject(s) - medicine , confounding , sun exposure , prospective cohort study , vitamin d and neurology , pregnancy , juvenile , case control study , physiology , disease , cohort study , biology , dermatology , genetics
Cutaneous sun exposure is an important determinant of circulating vitamin D. Both sun exposure and vitamin D have been inversely associated with risk of autoimmune disease. In juvenile idiopathic arthritis ( JIA ), low circulating vitamin D appears common, but disease‐related behavioral changes may have influenced sun exposure. We therefore aimed to determine whether predisease sun exposure is associated with JIA . Using validated questionnaires, we retrospectively measured sun exposure for 202 Caucasian JIA case–control pairs born in Victoria Australia, matched for birth year and time of recruitment. Measures included maternal sun exposure at 12 weeks of pregnancy and child sun exposure across the life‐course prediagnosis. We converted exposure to UVR dose and looked for case–control differences using logistic regression, adjusting for potential confounders. Higher cumulative prediagnosis UVR exposure was associated with reduced risk of JIA , with a clear dose–response relationship (trend P = 0.04). UVR exposure at 12 weeks of pregnancy was similarly inversely associated with JIA (trend P = 0.011). Associations were robust to sensitivity analyses for prediagnosis behavioral changes, disease duration and knowledge of the hypothesis. Our data indicate that lower UVR exposure may increase JIA risk. This may be through decreased circulating vitamin D, but prospective studies are required to confirm this.