Vitamine D et auto-immunité. Deuxième partie : aspects cliniques

Vitamin D status in rheumatoid arthritis patients: relation to clinical manifestations, disease activity, quality of life and fibromyalgia syndrome

AIM

To assess vitamin D levels in rheumatoid arthritis (RA) patients and to find their relation to clinical parameters, fibromyalgia syndrome (FMS), quality of life (QoL) and disease activity.

METHODS

The study included 63 RA patients and 62 controls. Clinical examination and laboratory investigations were performed. For patients, the Disease Activity Score (DAS-28), QoL index, Health Assessment Questionnaire II (HAQ II) and Modified Larsen score were calculated. 25-OH-vitamin D was measured in patients and controls.

RESULTS

The patients' mean age was 41.59 ± 9.69 years and disease duration 5.89 ± 3.67 years. The level of vitamin D in RA patients was significantly lower (23.11 ± 12.71 ng/mL) than that in the controls (32.59 ± 13.06 ng/mL) (P = 0.005) being deficient in 50.8%, insufficient in 23.8% and normal in 25.4%. The RA patients with FMS (n = 33) had significantly lower levels of vitamin D (19.08 ± 10.59 ng/mL) than those without (27.55 ± 13.51 ng/mL) (P = 0.008). The difference was significant on comparing those receiving hydroxychloroquine (17.39 ± 7.84 ng/mL) to those not (31.85 ± 13.85 ng/mL) (P < 0.001). Vitamin D significantly correlated with QoL index (r = 0.58, P < 0.001) and negatively with HAQ II (r = -0.36, P = 0.004) and BMI (r = -0.39, P = 0.001).

CONCLUSION

Special attention is required regarding vitamin D levels in RA patients with FMS and decreased QoL. Vitamin D should be corrected and supplementation considered among the RA management armamentarium.

[Vitamin D and autoimmunity]

Vitamin D acts at several levels in the immune systems to maintain immune tolerance. Vitamin D deficiency is a plausible environmental risk factor for autoimmune disease. Basic, genetic and epidemiological studies indicate a potential role of vitamin D in the prevention and the treatment of autoimmune diseases. Most of the epidemiological studies are cross-sectional, so that they are insufficient to establish a direct link between vitamin D deficiency and both disease risk and disease activity. Randomized, controlled trials are necessary.

[Prolonged corticosteroid therapy and diet]

In order to prevent adverse effects of long lasting treatments by glucocorticoids, some dietetic measures are underlined. If one was to strictly follow all these recommendations i.e., no salt, little glucose intake, high level of proteins, low calories diet, sufficient potassium intake and supplementation with calcium and vitamin D3, it would hardly be possible. The most common practice from doctors and patients is a salt-less diet, followed by calcium and vitamin D supplementation. Literature analysis on the opportunity of all these dietetic measures is surprisingly very poor, knowing that these drugs have been on the market for over fifty years. Only because osteoporosis has been on the front of the scene those past years a little more is known about calcium and vitamin D. It seems there are plenty opportunities on more studies on the subject.