Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Postpartum and the Risk of Developing Rheumatoid Arthritis; Results From the Swedish EIRA Study.

Bengtsson1,  Camilla, Orellana1,  Cecilia, Holmqvist2,  Marie, Berglund1,  Anita, Wedren3,  Sara, Klareskog3,  Lars, Alfredsson1,  Lars

Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
Clinical epidemiology unit, Dept of Medicine, Karolinska Institutet, Stockholm, Sweden
Rheumatology unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden

Background/Purpose:

It has previously been described that the incidence of RA is reduced during pregnancy but increased after delivery. The increased risk has been observed during the first three months1 up to two years after postpartum2. To our knowledge, no previous study has investigated the postpartum period and its effect on risk of the two subsets of RA, characterized by presence/absence of antibodies to citrullinated peptides (ACPA), separately.

Methods:

Data from the Swedish population-based EIRA (Epidemiological Investigation of Rheumatoid Arthritis) case-control study encompassing women aged 18–50 years. In total, 547 incident cases and 658 randomly selected controls, matched on age, sex and residency, were analysed. Parous women were compared with nulliparous women according to the risk of developing RA overall, ACPA-positive and ACPA-negative disease, respectively. In a separate analysis, women with partum the year before symptom onset was analysed. Odds ratios (OR) with 95% confidence interval (CI) were calculated using unconditional logistic regression.

Results:

In total, 360 (66%) of the cases and 431 (66%) of the controls were parous, meaning that there was no association between parity and the risk of RA overall. However, parity increased the risk of developing ACPA-negative RA (OR=1.5 (95% CI 1.0–2.3)). Women with partum the year before disease onset had more than a two-fold increased risk of ACPA-negative RA (OR=2.4 (95% CI 1.1–5.4)). There was no association between parity and the risk of ACPA-positive RA.

Conclusion:

Our results indicate that the postpartum period increases the risk of ACPA-negative RA, but has no association with ACPA-positive RA. Why postpartum is associated only with an increased risk of ACPA-negative RA, and what biologic mechanisms are involved, remains to be elucidated. Finally, our results indicate that the higher RA incidence among women than among men, might to some extent be explained by hormonal/reproductive factors, such as the postpartum period.

References:

1.Silman, A, Kay, A & Brennan, P. Timing of pregnancy in relation to the onset ofrheumatoid arthritis. Arthritis Rheum. 1992;35:152–5.

2.Wallenius, M, Skomsvoll, JF, Irgens, LM, Salvesen, KA, Koldingsnes, W, Mikkelsen, K, Kaufmann, C & Kvien, TK. Postpartum onset of rheumatoid arthritis and other chronic arthritides: results from a patient register linked to a medical birth registry. Ann Rheum Dis. 2010;69:332–6.

To cite this abstract, please use the following information:
Bengtsson, Camilla, Orellana, Cecilia, Holmqvist, Marie, Berglund, Anita, Wedren, Sara, Klareskog, Lars, et al; Postpartum and the Risk of Developing Rheumatoid Arthritis; Results From the Swedish EIRA Study. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :104
DOI:

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