Cohort study data published in the Journal of Rheumatology suggest that vitamin D deficiency may precipitate more active and severe disease in early rheumatoid arthritis (RA). Baseline vitamin D deficiency also predicted more rapid radiographic progression in early RA.
Investigators abstracted data from the ESPOIR study, a prospective cohort of patients with early RA who received treatment at 14 rheumatology clinics in France between 2002 and 2005. Patients who presented with 2 or more swollen joints for >6 weeks and <6 months were eligible for inclusion. Researchers excluded patients with prior exposure to disease-modifying antirheumatic drugs or steroids.
Participants attended study visits every 6 months for 2 years and then once a year; the present analyses used data from the baseline, 6-month, and 12-month visits. At each study visit, investigators measured disease activity and progression using the Disease Activity Score-28 for RA with Erythrocyte Sedimentation Rate (DAS28-ESR) and the Health Assessment Questionnaire Disability Index (HAQ-DI). They took radiographs of the hands, wrists, and forefeet every 6 months and defined radiographic progression as an increase from baseline of least 1 unit on the van der Heijde-modified Total Sharp Score (mTSS).
Researchers measured serum 25-hydroxyvitamin D levels at baseline; multivariate analyses compared patients with baseline vitamin D deficiency (<10 ng/mL) to patients with sufficient (≥10 ng/mL) levels. They conducted logistic regression to identify baseline predictors of 6- and 12-month disease outcomes.
In total, investigators included 645 patients from the ESPOIR cohort in regression analyses. Mean age was 48.8±12.2 years; 497 (77.1%) were women; and 592 (91.8%) were white. Baseline mean serum vitamin D level was 20.55±11.10 ng/mL; vitamin D deficiency was observed in 114 participants (17.7%).
At baseline, patients with vitamin D deficiency displayed higher DAS28-ESR (P =.007) and HAQ-DI (P =.001) scores than patients with serum vitamin D ≥10 ng/mL. In multivariate analyses, baseline vitamin D deficiency was the strongest predictor of HAQ-DI ≥0.5 at month 6 (odds ratio [OR] 1.7; 95% CI, 1.05-2.76; P =.031). At 12 months, vitamin D deficiency was also associated with progression on mTSS (OR 1.9; 95% CI, 1.19-3.03; P =.007) and greater erosion score (OR 1.89; 95% CI, 1.18-3.03; P =.007).
In a prospective cohort of patients with early RA, vitamin D deficiency was associated with more active and severe disease at baseline and greater 12-month radiographic progression. As study limitations, investigators noted that data on other laboratory figures, such as calcium or phosphorus, were not available. In addition, the study cohort was restricted to patients with early RA rather than moderate or severe disease. Even so, these results suggest that certain environmental factors, such as low sun exposure, may play a role in RA pathogenesis.
Mouterde G, Gamon E, Rincheval N, et al. Association between vitamin D deficiency and disease activity, disability, and radiographic progression in early rheumatoid arthritis. The ESPOIR cohort [published online December 15, 2019]. J Rheumatol. doi: 10.3899/jrheum.190795