Hypovitaminosis D among rheumatology outpatients in clinical practice

A role for vitamin D in the pathogenesis of autoimmune and inflammatory diseases is emerging. We undertook an audit of 25-hydroxyvitamin D (25OHD) investigation and treatment in rheumatology outpatients.

Serum 25OHD requests were matched to electronic medical records from rheumatology and metabolic bone clinics (April 2006-March 2007). Data were analysed separately for two groups, 'Documented osteoporosis/osteopaenia' (Group 1) and 'General rheumatology outpatients' (Group 2, sub-divided by diagnosis). Hypovitaminosis D was defined by 25OHD levels <50 nmol/l. Values were compared with healthy adults to calculate geometric z-scores.

A total of 263 patients were included (Group 1, n = 122; Group 2, n = 141) with an overall median 25OHD of 44 nmol/l. The 25OHD level among general rheumatology patients (median 39 nmol/l, mean z score -1.2, was statistically significantly lower than among osteoporotic/osteopaenic patients (median 49 nmol/l, mean z score of -0.9, p < 0.05 for the difference). 25OHD was lower in inflammatory arthritis and chronic pain/fibromyalgia than in other groups. Prescribing was recorded in 100 in Group 1 (of whom 95% were prescribed calcium/800 IU cholecalciferol) and 83 in Group 2 (91% calcium/800 IU). Only 31% of the patients with 25OHD <50 nmol/l would have been identified using general guidelines for screening patients at 'high risk' of hypovitaminosis D.

Improved guidelines for managing hypovitaminosis D in rheumatology patients are needed. We found a high prevalence of hypovitaminosis D among secondary care patients in rheumatology and widespread supplementation with 800 IU cholecalciferol. Substantially reduced levels of serum 25OHD were identified among patients with inflammatory arthritis and chronic pain.