Date: Sunday, November 7, 2021
Session Type: Poster Session B
Session Time: 8:30AM-10:30AM
Background/Purpose: Peripheral blood red cell distribution width (RDW) correlates with disease activity in rheumatoid arthritis (RA) and is associated with subsequent mortality in non-RA patient populations. Although RDW and 25-hydroxyvitamin D (25(OH)D) levels are inversely correlated in community dwelling adults, the association between 25(OH)D status and RDW in RA has not been characterized. We investigated the relationships between baseline 25(OH)D status, RDW, and methotrexate (MTX) therapy in RA.
Methods: This was a retrospective cohort study of RA patients who fulfilled 1987 ACR classification criteria for RA and had a 25(OH)D level obtained within one year prior to MTX initiation at a single center VA Rheumatology Clinic (n=167). We evaluated vitamin D levels before and after MTX therapy start and evaluated the relationships between RDW, 25(OH)D levels, and 25(OH)D supplementation (multivitamin or higher dose supplementation) using Wilcoxon Signed Rank Test for paired analyses and Spearman Rank Sum Test for analyses of correlations.
Results: Prior to MTX therapy, 41% (n=69) were receiving 25(OH)D supplementation. After MTX therapy, 85% (n=142) were receiving 25(OH)D supplementation and 55% (n=92) were still receiving MTX at the last lab value. RDW inversely correlated with 25(OH)D levels prior to MTX (n=167; r=-0.19; p=0.01). This relationship also was observed in the subgroup where patients were receiving 25(OH)D supplementation (n=69; r=-0.25; p=0.04) but not in the subgroup not receiving supplementation (n=94; r=-0.07; p=0.52) prior to MTX.
25(OH)D level after any MTX therapy was significantly higher compared to baseline level (n=167; p< 0.001), and of those patients who remained on MTX therapy at last lab value significantly higher 25(OH)D level also was observed (n=92; p< 0.001). RDW was significantly higher compared to baseline level after any MTX therapy (n=167; p< 0.001), and of those patients who remained on MTX therapy at last lab value higher RDW again was observed (n=92; p< 0.001). After start of MTX therapy, the relationship between 25(OH)D level and RDW was no longer observed (n=92; r=0.13; p=0.21).
Conclusion: RDW and 25(OH)D levels are inversely correlated in RA patients on 25(OH)D supplementation prior to initiating MTX therapy. The relationship between 25(OH)D and RDW after MTX therapy start was no longer observed, potentially secondary to MTX-driven anemia or MTX-mediated inflammatory control. Whether this relationship reflects overlapping inflammatory pathways driving RDW and 25(OH)D levels, or whether this is a causal relationship is yet to be determined. Specifically, whether 25(OH)D is a mediator of immunologic homeostasis in RA will need to be further elucidated.
To cite this abstract in AMA style:Malakooti S, Wilson B, Bej T, Kostadinova L, Lange A, O'Mara M, Zidar D, Mattar M, Anthony D. Red Cell Distribution Width Is Associated with Baseline 25-hydroxyvitamin D Level Before Methotrexate Therapy in Rheumatoid Arthritis [abstract]. Arthritis Rheumatol. 2021; 73 (suppl 9). https://acrabstracts.org/abstract/red-cell-distribution-width-is-associated-with-baseline-25-hydroxyvitamin-d-level-before-methotrexate-therapy-in-rheumatoid-arthritis/. Accessed October 1, 2022.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/red-cell-distribution-width-is-associated-with-baseline-25-hydroxyvitamin-d-level-before-methotrexate-therapy-in-rheumatoid-arthritis/