Background/Purpose:

There is increasing evidence that vitamin D has immunoregulatory properties in autoimmunity. In established rheumatoid arthritis (RA) there appears to be an inverse association between serum vitamin D levels and disease activity scores (DAS-28) (Rossini et al., Arthritis Res Ther, 2010; 12(6);R216) although others suggest this may be skewed by the global health visual analogue scale (GH-VAS) (Higgins et al., Clin Rheumatol, 2013 Jun; 32(6): 863-7). Given the confounding problems in established RA, such as medications or lifestyle, we wished to investigate the role of vitamin D in early RA.

Methods:

We retrospectively analysed an inception cohort of patients presenting to an Early Arthritis Clinic at the Freeman Hospital, Newcastle-upon-Tyne between October 2007 – March 2009. Serum 25 hydroxy vitamin D levels (25OHD measured using the DaiSorin Liaison automated immunoassay), DAS-28, CRP, ESR, TJC (tender joint count), SJC (swollen joint count), GH-VAS and autoantibody status were measured at baseline. Diagnoses were confirmed at 1 year follow-up. Statistical analyses involved linear regression, binary logistic regression and Mann-Whitney U tests and were all performed using SPSS (statistics 19) with significance when p<0.01. Where applicable all analyses were corrected for age and sex.

Results: Of a total cohort of 453 patients, complete data was available for 344 (76%; 2:1 females:males, mean age 49 [range 16-97], median symptom duration 16 weeks [range 1-230]). No significant association was seen between serum 25OHD and GH-VAS, SJC, TJC, ESR, CRP, auto-antibodies or disease outcome in this cohort (corrected for age and sex). Amongst the 73 (21%) patients diagnosed with RA (2:1 females:males, mean age 49 [range 18-88]), associations between serum 25OHD and DAS-28, GH-VAS, SJC, TJC, ESR, CRP and autoantibody status were again not seen (corrected for age and sex). However, in those diagnosed with osteoarthritis, OA, (n=58; 3:1 females:males, mean age 55 [range 47-78]), we identified a significant inverse association between GH-VAS and serum 25OHD (p=0.006), although the other measured parameters (as above) were again non-significant (corrected for age and sex). Notably symptom duration was significantly higher in the OA group than in the RA group (median 24 versus 12 weeks; p<0.0005).

Conclusion:

This is the first study to our knowledge to look at the effects of serum 25OHD in early RA.  Contrary to published work in established RA, our data suggest that serum 25OHD does not impact on disease activity parameters (including GH-VAS) in early disease.  We do however demonstrate a significant inverse association between GH-VAS and serum 25OHD in OA patients. The significantly prolonged symptom duration observed in this group may have permitted an association to develop between perceived health and vitamin D status, for example driven by reduced mobility / sunlight exposure.  Similar factors may confound apparent associations between RA and vitamin D status in established disease. Larger scale studies are needed to validate our preliminary findings in early arthritis

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-effect-of-vitamin-d-on-early-rheumatoid-arthritis-a-retrospective-cohort-analysis/