Vitamin D deficiency is common among patients with juvenile idiopathic arthritis and linked to higher disease activity and other medical complications, a study finds.
The study, “Vitamin D deficiency is associated with higher disease activity and the risk for uveitis in juvenile idiopathic arthritis – data from a German inception cohort,” was published in the journal Arthritis Research & Therapy.
Juvenile idiopathic arthritis (JIA) includes a group of chronic inflammatory conditions that affect the joints, causing swelling, stiffness, and pain in children.
Previous studies have shown that vitamin D deficiency and/or lack of calcidiol [25(OH)D] — the hormone precursor of vitamin D produced in the liver — are associated with “higher incidence and severity of autoimmune disorders, such as type 1 diabetes mellitus, chronic inflammatory bowel disease, rheumatoid arthritis (RA) and multiple sclerosis.”
Researchers from the German Rheumatism Research Center in Berlin set out to measure the levels of calcidiol in JIA patients and determine their relationship with disease activity and other medical complications.
The study focused on a subgroup of 360 children under 17 years of age and recently diagnosed with JIA, who had been enrolled in a previous prospective, multicenter, observational study launched in 2010, called ICON.
Two blood samples were collected from each participant — one during the first two years of the study, and the other during the follow-up period of three years — to measure their calcidiol levels, which were then compared with those of individuals from the general population, who were matched by age, sex, migration status, and the month of blood draws.
Findings showed that nearly half of the patients (44%) had lower levels of calcidiol (less than 20 ng/ml) in the first blood sample and a quarter (25%) in both samples were deficient. However, vitamin D deficiency was so common that 62% of the general population sample had it.
Further analysis revealed that calcidiol levels were inversely correlated with disease activity and the risk of developing other medical complications, including extended JIA (also known as oligoarthritis) and uveitis, a condition that causes inflammation, swelling and destruction of eye tissues.
“A limitation of this study is that any use of vitamin D supplementation was not recorded,” the researchers noted.
“In patients with JIA, vitamin D deficiency is associated with higher disease activity and a higher risk of developing uveitis and possibly the extended form of oligoarthritis,” the researchers wrote. “To further clarify if cholecalciferol [vitamin D3] substitution in order to achieve a sufficient (25‐hydroxyvitamin D) level might have the potential to prevent the development of uveitis and the extended form of oligoarthritis, these associations must be confirmed by an interventional study.”