The effect of vitamin D levels on the assessment of disease activity in rheumatoid arthritis

Abstract

Disease activity in rheumatoid arthritis (RA) is assessed by a combination of objective and subjective tests, combined to produce a disease activity score in 28 joints (DAS28). There is some evidence that RA disease activity, as assessed by DAS28, can be influenced by vitamin D levels. It is difficult to know whether this is due to a true immunomodulatory effect of vitamin D or a more subjective effect of low vitamin D on pain perception. We addressed this issue by comparing vitamin D levels with disease activity, analysing each component of the DAS28 score separately. We measured 25-hydroxy vitamin D levels in 176 outpatients with RA at two different centres and recorded a DAS28 score using an ESR checked at the same time. We calculated DAS28 both with and without the patient's rating of their symptoms on the visual analogue score (VAS) to assess the effect of VAS on DAS28. The vitamin D results were expressed as nanomole per litre with 50 nmol/l taken as the lower limit of normal. We calculated mean levels of vitamin D and undertook a multivariate regression analysis to assess correlations between vitamin D levels and DAS28 (and its individual components), corrected for centre, age and gender. The overall mean DAS28 score was 3.66 (SE ± 0.11) using all four criteria and 3.43 (SE ± 0.10) using just three criteria (omitting VAS). The mean vitamin D level was 39.42 nmol/l (SE ± 1.55). There was no significant correlation between vitamin D and DAS28 scores with or without the inclusion of VAS. However, there was a significant inverse relationship between vitamin D and VAS itself (coefficient = 0.249, p = 0.013). The mean DAS28 score was greater in vitamin D-deficient patients and this was explained by their higher VAS scores. Our data confirms that vitamin D deficiency is common in RA. This paper provides evidence that the VAS component, assessing patient perception of symptoms, is inversely related to vitamin D, with lower levels producing higher VAS values. Although there was no overall correlation between vitamin D levels and DAS28, patients may perceive themselves or be perceived by assessors as having responded less well to disease modification in the presence of vitamin D deficiency. This could have major implications for subsequent management, and clinicians need to be aware of the potential confounding effect of vitamin D deficiency in assessing RA disease activity using the full DAS28 tool.

Association of Vitamin D with Disease Activity in Rheumatoid Arthritis and Ankylosing Spondylitis

“…However, we found no statistical negative correlation between vitamin D levels and DAS28. In some previous studies, no significant association was determined between disease activity and vitamin D levels and their results were consistent with our study [10,14,15]. On contrary, some studies reported a significant negative correlation [9,[11][12][13].…”

“…However, the complaints due to vitamin D deficiency may lead to the delusion which increases the disease activity in cases with RA. It is reported that the clinician should consider this situation when assessing the activation of the disease [10].…”

“…Furthermore, it was shown that vitamin D addition prevented the onset and progress of inflammatory arthritis in rats [7,8]. However, there are different opinions about the relationship between vitamin D levels and disease activities in RA and AS patients in the literature [9][10][11][12][13][14][15][16][17].…”

Relationship between Serum 25-Hydroxyvitamin D Levels, Disease Activity and Anti-Cyclic Citrullinated Peptide Antibody Levels in Indian Rheumatoid Arthritis Patients

“…This might have major implications for subsequent management, as they may then be subjected to treatment escalation in spite of the absence of any ongoing disease activity. This carries implications at both clinical and financial levels [46]. Hence, clinicians need to be aware disease activity in their study participants.…”

Vitamin D in rheumatoid arthritis

“…Through Editorial recruited from 22 Italian rheumatology centers, concluded that lower serum 25(OH)D 3 levels were associated with active disease by a DAS 28 score of >3.1, lack of remission and poor response to therapy, even after adjusting for sunlight exposure and BMI [11]. In a recent study from the UK, however, there was no significant correlation between 25(OH)D 3 and DAS 28 scores with or without the inclusion of VAS, while there was a significant relationship between 25(OH)D 3 and VAS itself [12]. The mean DAS 28 scores were greater in 25(OH) D 3 -deficient patients, being explained by their higher VAS scores.…”