The prevalence of vitamin D deficiency in consecutive new patients seen over a 6-month period in general rheumatology clinics

Abstract

The objectives of this study are to assess: (a) the prevalence of vitamin D deficiency among new patients attending rheumatology outpatient departments, (b) the age profile of these low vitamin D patients and (c) whether any diagnostic category had a particularly high number of vitamin D-deficient patients. All new patients seen consecutively in general rheumatology clinics between January to June 2007 inclusive were eligible to partake in this study, and 231 out of 264 consented to do so. Parathyroid hormone, 25-hydroxyvitamin D, creatinine, calcium, phosphate, albumin and alkaline phosphatase levels were measured. We defined vitamin D deficiency as ≤53 nmol/l and severe deficiency as ≤25 nmol/l. Overall, 70% of 231patients had vitamin D deficiency, and 26% had severe deficiency. Sixty-five percent of patients aged ≥65 and 78% of patients aged ≤30 years had low vitamin D levels. Vitamin D deficiency in each diagnostic category was as follows: (a) inflammatory joint diseases/connective tissue diseases (IJD/CTD), 69%; (b) soft tissue rheumatism, 77%; (c) osteoarthritis, 62%; (d) non-specific musculoskeletal back pain, 75% and (e) osteoporosis, 71%. Seasonal variation of vitamin D levels was noted in all diagnostic groups apart from IJD/CTD group, where the degree of vitamin D deficiency persisted from late winter to peak summer. Very high prevalence of vitamin D deficiency was noted in all diagnostic categories (p = 0.006), and it was independent of age (p = 0.297). The results suggest vitamin D deficiency as a possible modifiable risk factor in different rheumatologic conditions, and its role in IJD/CTD warrants further attention.