Chronic Pain and Vitamin D (DOVID)

Non-systematized chronic musculoskeletal pains are a frequent reason for consulting in general practice. The possible causes are numerous and sometimes nonspecific. In some cases, the etiologic investigation of patients with non-systematized and chronic musculoskeletal pain can not highlight any organic cause. Several studies have shown a link between these symptoms and vitamin D deficiency, characterized by a blood level of 25 (OH) vitamin D < 20.8ng/ml. This deficit is easy to identify and to correct through proper vitamin D supplementation with few side effects. Nevertheless, it remains unknown and vitamin D deficiency is rarely considered as a possible etiology in patients with chronic pain. We hypothesize that vitamin D supplementation in patients with non-systematized musculoskeletal pain and deficient in vitamin D could improve painful symptoms. We aim to perform a double-blind randomized controlled trial, vitamin D versus placebo, to assess the pain improvement after vitamin D supplementation.

Patients from the vitamin D arm will receive an orally supplementation of 600 000 UI cholecalciferol in 3 doses: 200 000 UI at baseline (day 1), 200 000 UI on day 15 and 200 000 UI on day 30. Cholecalciferol will be presented in blisters, in a non-differentiable form in appearance and taste from placebo, either for the patient or the doctor

Patients from the placebo arm will receive 3 doses of placebo to be taken orally: one at baseline (day 1), one on day 15, one on day 30. Placebo will be presented in blisters in a non-differentiable form in appearance and taste from cholecalciferol either for the patient or the doctor.

Proportion of patients in the two groups who reported a decrease in the overall pain after 3 months of treatment with vitamin D versus placebo.

item 5 of the Brief Pain Inventory will be measured in each patient to assess the overall pain score at inclusion and after 3 month of treatment with vitamin D or placebo

: Proportion of patients in both groups reporting an evolution of the minimum and the maximum of intensity of pain

item 3 and 4 of the Brief Pain Inventory will be measured in each patient to assess the minimum and the maximum pain scores at inclusion, after 45 days and after 3 months of treatment with vitamin D or placebo

item 9 of the Brief Pain Inventory will be measured in each patient to assess the score of the impact of pain on daily activities at inclusion, after 45 days and after 3 months of treatment with vitamin D or placebo

Patients of both groups will be asked at inclusion, after 45 days and after 3 months, if they took analgesic drugs: name, class and dose of each treatment will be registered in a standardized questionnaire

Proportion of patients in both groups reporting a decrease in the consumption of care (consultations and work stoppages)

Patients of both groups will be asked at inclusion, after 45 days and after 3 months, if they consulted any health care professional : which health care professional, how many time, the reason for consultation and work stoppages will be registered in a standardized questionnaire

Quality of life will be measured in patients of both groups by the SF-36 questionnaire, at inclusion and after 90 days.

Inclusion Criteria: Women and men Aged 18-50 years (included) Consulting their general practitioner With chronic and diffuse musculoskeletal pain, without known etiology, lasting for at least 3 months With a 25(OH)vitamin D deficiency <20.8 ng/ml (52 nmol/l) at inclusion Who signed the consent form Exclusion Criteria: Identifiable source of pain requiring an appropriate specific management Disease or treatment that may interfere with the metabolism of vitamin D Current or previous hypercalcemia or hypercalciuria, treatment with digitalics and patients with history of nephrolithiasis Current treatment with vitamin D or at least one vitamin D vial taken over the previous 6 months Pregnancy or breastfeeding not affiliated to a social security system Refusal or inability to give consent