SAN DIEGO — Vitamin D supplementation did not lessen fibromyalgia symptoms in a small trial, a finding that casts doubt on the theory that vitamin D deficiency underlies some patients' pain and that screening vitamin D levels would identify patients who would benefit from supplementation, Dr. Ann Warner said in a poster presentation at the annual meeting of the American College of Rheumatology.
She performed two studies examining the vitamin D hypothesis. In one study, Dr. Warner, a rheumatologist who practices in Kansas City, Mo., took 50 fibromyalgia patients with insufficient serum levels of vitamin D (a 25-hydroxyvitamin D level less than 20 ng/mL) and randomized them to weekly doses of 50,000 IU of vitamin D or to placebo for 3 months.
The 25 patients randomized to supplementation had a higher mean pain score on a visual analog scale at baseline compared with the patients who received placebo (74 mm vs. 61 mm). The mean pain score of patients given supplemental vitamin D improved after 3 months, falling to 64 mm. However, the mean visual analog scale score of the control patients fell to a similar degree, to 54 mm, and neither group's changes were statistically significant.
Patients in the control group showed a slight, but significant improvement on the functional pain score, while the supplemented group did not.
In the second study, Dr. Warner compared 25-hydroxyvitamin D levels in 104 patients with osteoarthritis with levels in 184 fibromyalgia patients.
There was no statistically significant difference in mean levels between the groups (28.76 ng/mL for the osteoarthritis group vs. 29.16 for the fibromyalgia group) even though there was a slightly higher percentage of patients with fibromyalgia who were insufficient, 29% vs. 20%.