Patients with psoriatic arthritis (PsA) have a high prevalence of vitamin D insufficiency, with no evidence of seasonal or geographic variation or association between vitamin D levels and disease activity, according to a study published online July 11 in Arthritis Care & Research.
Zahi Touma, M.D., from the Toronto Western Hospital, and colleagues investigated the prevalence of vitamin D deficiency and insufficiency in 302 patients with PsA, its seasonal and geographic variation, and the possible correlation with disease activity. The study was conducted in a northern geographic area (North) and a subtropical region (South), from March to August 2009. A total of 258 participants were assessed in winter and 214 in summer, with most participants assessed in both seasons. Demographic and clinical data, skin prototype, and serum 25-hydroxyvitamin D (25[OH] vitamin D) levels were measured for the participants.
The investigators found that, in the winter, 25(OH) vitamin D levels were insufficient in 55.7 and 50.9 percent of patients in the North and South locations, respectively; and, in the summer, levels were insufficient in 58.6 and 62.2 percent of patients in the North and South, respectively. No association was observed between vitamin D levels, race, employment status, skin phototype, seasonal and geographic interaction, or disease activity in summer or winter. There was no association between disease activity in summer and vitamin D levels in winter.
"A high prevalence of vitamin D insufficiency among PsA patients was found. There was no seasonal variation in 25(OH) vitamin D levels among PsA patients in the southern and northern sites. No association could be established between disease activity and vitamin D level," the authors write.
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