Background/Purpose: Rheumatoid Arthritis (RA) is a disease that can have a long sub-clinical phase. During this phase the person with pre-RA could have factors in the peripheral blood, that could confer a risk of developing RA to a blood recipient. One factor could be anti-citrullinated peptide/protein antibodies (ACPA), which has a high specificity for RA and has been found in blood donors to precede the clinical RA by several years (1). In experimental murine models it has been shown that ACPA can not only induce but also enhance arthritis (2). Previous studies on risk of RA and blood transfusion have been few and inconclusive, and none of them described the blood donor population. Based on these findings we speculated whether blood products from a donor with subclinical RA at the time of donation, could be a risk factor of RA development in the recipient.

Methods: We used the Scandinavian Donations and Transfusions database (SCANDAT2) linked with Danish and Swedish nationwide health outcomes registers to attain complete follow-up for up to 47 years regarding hospital care, cancer, and death. In 2015 the database contains 25.523.334 donation records, 21.318.794 transfusion records, and 3.692.653 unique persons with valid identification, presently followed over 40 million person-years(3). Incident RA was defined as having two registered RA diagnoses in the national health registers within a two-year period. Taking a look-back approach, we first identified all donors in SCANDAT2 diagnosed with RA subsequent to their earliest registered donation. We then followed all recipients in SCANDAT2 for the occurrence of RA, starting follow-up one year after first registered transfusion. In analyses, we then assessed the occurrence of RA in recipients according to blood donor characteristics, e.g. whether exposed to donors with subsequent RA or not. Rate ratios adjusted for patient age, sex, ABO blood group, birth cohort, geographic region, and number of transfusions were calculated.

Results: We identified 55 recipients who developed RA during 72017 person-years of follow-up after receiving blood from donors who developed RA (55 events/72017 person-years). For comparison, we identified 9370 recipients who developed RA during 11,733,459 person-years of follow-up after receiving blood from donors who remained free of RA. These figures corresponded to a rate ratio of 1.01 (95% confidence interval 0.73-1.39). Detailed data on recipient RA occurrence by time since transfusion and according to donor rheumatoid factor status, age and sex will be presented.

Conclusion: We found no evidence that a pre-RA condition in the blood donor contributes significantly to a higher risk of developing RA in the transfusion recipients. References:

1. Nielen MM, et al. Specific autoantibodies precede the symptoms of rheumatoid arthritis: a study of serial measurements in blood donors. Arthritis and rheumatism. 2004;50(2):380-6.

2. van Venrooij WJ, et al. Anti-CCP antibodies: the past, the present and the future. Nat Rev Rheumatol. 2011;7(7):391-8.

3. Edgren G, et al. The new Scandinavian Donations and Transfusions database (SCANDAT2): a blood safety resource with added versatility. Transfusion. 2015;55(7):1600-6.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-of-rheumatoid-arthritis-after-transfusion-of-blood-from-donors-later-diagnosed-with-rheumatoid-arthritis-a-retrospective-cohort-study/