Background/Purpose: Pre-eclampsia is a pregnancy-related syndrome with potentially fatal outcomes. In RA, high disease activity has been associated to adverse pregnancy outcomes such as preterm birth and low birth weight. The risk of pre-eclampsia in relation to disease activity and anti-rheumatic treatment in women with chronic inflammatory arthritis has not been assessed. The objective of this study was to evaluate the overall risk of pre-eclampsia in pregnant women with RA, Axial (Ax)SpA, and PsA and to assess the impact of disease activity and anti-rheumatic treatment.

Methods: We conducted a register-based matched cohort study using data from Swedish and Danish nationwide clinical and health registers. We identified RA, AxSpA, and PsA singleton pregnancies (2006-2018) by linking medical birth registers (MBR) to rheumatology registers in Sweden (SRQ) and Denmark (DANBIO). Control pregnancies from the MBRs were matched 1:10 on age, birth year, and parity.
We obtained information on anti-rheumatic treatment nine months before (pre-pregnancy) and during pregnancy, and disease activity (DAS28-CRP/HAQ/CRP) during pregnancy. Information on pre-eclampsia was obtained from the National Patient Registers. The risk of pre-eclampsia was estimated using logistic regression and presented by odds ratios (aOR) with 95% confidence intervals (CI). Adjustments were made for maternal age, parity, year, country, BMI, smoking, and educational level.

Results: We identified 1739 RA, 819 AxSpA, and 489 PsA pregnancies. For RA and AxSpA pregnancies, there were no major differences in maternal characteristics compared to their control pregnancies. Pregnant women with PsA were more likely to be obese, smokers, and less educated compared to their controls.
We found an overall increased risk of pre-eclampsia in PsA pregnancies as compared to control pregnancies (aOR 1.85; 95% CI 1.10, 3.12), whereas the risk was not increased in RA or AxSpA (Table 1). Women with RA receiving pre-pregnancy combination therapy (conventional synthetic (cs)DMARD, biologic (b)DMARD, and CS in any combination of at least two) had a moderately increased risk compared to controls, whereas no treatment or monotherapy (csDMARD, bDMARD, or CS) did not increase the risk (Table 1). For PsA, pre-pregnancy monotherapy was associated with pre-eclampsia (Table 1). We observed no significantly increased risk of pre-eclampsia for any of the disease groups when stratifying on treatment during pregnancy.
Among RA exposed pregnancies with available information on disease activity during pregnancy (n=756, 43%), we observed a doubled risk of pre-eclampsia associated with high disease activity compared to control pregnancies (Table 2). In AxSpA and PsA, we found no such association, but numbers of events were low (Table 2).

Conclusion: Pregnant women with PsA, but not AxSpA, are at increased risk of pre-eclampsia overall. For RA pregnancies, our results indicate that severe disease, i.e. combination treatment before pregnancy and high disease activity during pregnancy, is a risk factor for pre-eclampsia.

Acknowledgements
Partly funded by NordForsk and FOREUM, The Danish Rheumatism Association, and the Swedish Rheumatism Association.

Only singleton pregnancies. One woman may contribute with one or more pregnancies. ORs were estimated using logistic regression and generalized estimation-equation method. 1) csDMARD, bDMARD, or CS, 2) csDMARD, bDMARD, and CS in any combination of at least two, 3) Matched 1:10 on maternal age group, parity, and year, 4) Adjusted for maternal age, parity, year, country, BMI group, smoking, and educational level, 5) Not adjusted for BMI due to low numbers. Abbreviations: AxSpA, Axial SpA; BMI, Body Mass Index; CI, Confidence Interval; OR, Odds Ratio.

Only singleton pregnancies. One woman may contribute with one or more pregnancies. ORs were estimated using logistic regression and generalized estimation-equation method. 1) Matched 1:10 on maternal age group, parity, and year, 2) DAS28-CRP was calculated including CRP and without Global Health-Visual Analog Scale (VAS) 3) No measurements of either DAS28-CRP, HAQ, or CRP 4)No measurements of neither HAQ, nor CRP, 5) Adjusted for maternal age, parity, year, country, BMI group, smoking, and educational level. Abbreviations: AxSpA, Axial SpA; BMI, Body Mass Index; CI, Confidence Interval; DAS28-CRP, 28-joint DAS, CRP adjusted; NA, Not Applicable; OR, Odds Ratio.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-of-pre-eclampsia-and-impact-of-disease-activity-and-anti-rheumatic-treatment-in-women-with-rheumatoid-arthritis-axial-spondylarthritis-and-psoriatic-arthritis-a-collaborative-matched-cohort-s/