Severe vitamin D deficiency could be responsible for persistent rheumatoid arthritis disease activity, according to a new study.
The goal of this study was to assess the relationship between vitamin D deficiency and active rheumatoid arthritis, and the role of supplements in improving disease activity. Vitamin D deficiency has been linked to immune disorders, including rheumatoid arthitis, but how much vitamin D is enough, has been a bit of a controversy.
The researchers found that supplementation of vitamin D in rheumatoid arthritis patients with persisting disease activity and vitamin D deficiency, contributed to significant improvements in disease activity within a short duration. The findings appear in the Oct. 20 issue of The International Journal of Rheumatic Diseases.
The study was conducted with 149 patients with active rheumatoid arthritis. Researchers observed the impact of vitamin D supplementation on illness duration, pain severity, tender joint counts, swollen joint counts, serum vitamin D levels, erythrocyte sedimentation rate and C-reactive protein.
The mean participant age at recruitment was 49, with 94% being female and 6% being male. The average duration of illness was 78 months, and average length of disease-modifying anti-rheumatic drugs treatment was 44 months. Participants also had other co-morbid conditions, including diabetes, hypothyroidism, asthma, and benign prostatic hyperplasia.
Patients were divided into four groups:
1. high disease activity with low vitamin D
2. high disease activity with normal vitamin D
3. low disease activity with low vitamin D
4. low disease activity with normal vitamin D
Group 1 exhibited the greatest degree of vitamin D deficiency. These participants had a disease activity score of 28 joints-CRP (DAS28-CRP) of >2.6 and a serum vitamin D level of 20 ng/mL. They were recruited into open-label vitamin D supplementation of 60,000 IU once a week for six weeks. They tapered down to the same amount once a month for three months. Researchers reassessed participants at the end of the three months for erythrocyte sedimentation rate, C-reactive protein and vitamin D levels.
After three months, 59 patients were re-evaluated, and results showed an improvement in disease activity for more than 50% of patients. Mean DAS28-CRP showed a statistical improvement from 3.68 +/- 0.93 to 3.08 +/- 1.11 after supplementation. Serum blood levels also improved from 10.05 +/- 5.18 to 57.21 +/- 24.77 ng/mL during the same timeframe.
Data showed no significant improvement or change in erythrocyte sedimentation rate and C-reactive protein levels, likely due to small population sampling, but statistically significant changes emerged in joint count and pain scale measures. Additionally, findings showed vitamin D may improve patients’ pain perception (pain threshold), impacting TJC.
Researchers noted the small patient population available for screening could be a limiting factor – more participants could be needed to show real differences in the impact of vitamin D on various stages of active rheumatoid arthritis. In addition, they concluded, it is possible the impact of vitamin D on inflammation is trivial.