Unexplained musculoskeletal pain in people of South Asian ethnic group referred to a rheumatology clinic - relationship to biochemical osteomalacia, persistence over time and response to treatment with calcium and vitamin D.

BACKGROUND

Hypovitaminosis D continues to be a problem for South Asian people living in the UK. This study investigates the association between widespread unexplained pain and biochemical osteomalacia in this group of people.

METHODS

All South Asian patients attending with unexplained widespread pain (CWP) over a two-year period had biochemical tests for osteomalacia: calcium, phosphate, alkaline phosphatase, vitamin D (25OHD), and parathyroid hormone (PtH). For comparison, a control group consisted of patients in whom a specific rheumatic diagnosis (SRD) had been made. A follow up questionnaire was sent enquiring about pain, disability and dietary habits. A small proportion of the responders attended for a further set of biochemical tests for osteomalacia.

RESULTS

The majority of patients in both groups had a raised PtH (124/220, 57%) and a low 25OHD (117/160, 73%). Where data on both PtH and 25OHD were available, 47% (64/137) had a combination of reduced 25OHD and raised PtH. Few of these patients had abnormal calcium, phosphate or alkaline phosphates. From the postal questionnaire the prevalence of disability and continuing pain was high in both groups, with the majority of respondents complaining of difficulty with activities and nearly half needing help. Pain was widespread, the same or worse and graded above 7/10 for 69% and 78% of respondents in the CWP and SRD groups respectively. Overall, sixty one percent of respondents thought their gait pattern had changed in the last year. No significant differences were seen between respondents based on diagnosis (CWP or SRD), initial or subsequent PtH levels, or current calcium and vitamin D consumption. At the time of the second blood test, 52% of those with an elevated PtH on the first test now had a normal PtH value but 31% of those with a normal PtH first time had an elevated PtH.

CONCLUSION

This observational study conducted in a rheumatology clinic in the north of England has shown high levels of biochemical osteomalacia in people of South Asian origin and high levels of persistent pain and disability, unrelated to diagnosis, biochemical status or treatment with calcium and vitamin D.