Axial spondyloarthritis (axSpA) disease activity in pregnant women appears to remain mostly stable, with slight worsening in the second trimester, according to results of a prospective study.

“In the largest prospective study to date exploring disease activity during pregnancy in women with axSpA, we found that the majority experienced stable, low disease activity,” Kristin Ursin, MD, of the Trondheim (Norway) University Hospital and her associates wrote in Rheumatology. “In accordance with two previous studies, we found a small increase in disease activity in the second trimester.”

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Prior to this study, the disease activity of axSpA in pregnant women was not well known, with several previous studies presenting divergent results, the authors said. They designed and conducted a prospective study of 179 pregnancies in 166 Norwegian women who were included in the Norwegian nationwide register, RevNatus, between January 2006 and November 2016.

All women in the study fulfilled the Assessment of SpondyloArthritis International Society criteria for axSpA and had seven clinic visits throughout their pregnancy: one before conception, one at each trimester, another at 6 weeks, and two visits 6 and 12 months after delivery. No differentiation was made between women with radiographic or nonradiographic axSpA. At each visit, patients’ disease activity was determined using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), which is calculated based on six patient factors scored from 1 to 10, including: fatigue, back pain, peripheral joint pain and swelling, localized tenderness, duration of morning stiffness, and severity of morning stiffness. A disease score of 4 is commonly used to define active disease. Disease activity was also assessed by measuring C-reactive protein (CRP). Women’s function and health was also assessed using the Bath Ankylosing Spondylitis Functional Index (BASFI), scored similarly to the BASDAI, and the RAND-36 questionnaire to assess general health.

The research team found that, across the span of pregnancy, axSpA disease activity was relatively low and consistent throughout the study. But there was a significant relationship between disease activity and time (P = .029) in which disease activity was highest during the second trimester and proved to be significantly higher than 6 weeks after giving birth (mean BASDAI 3.97 vs. 3.46, P = .005). In fact, 45% of women had active disease in their second trimester (BASDAI of 4 or greater). But among women with data from the second trimester and 6 weeks post partum, 42% had a decrease in BASDAI score of 1 or more, and 22% had an equivalent increase. CRP values remained low and stable throughout the study.

Like the BASDAI scores, physical function and well being seemed to correlate with later time points during pregnancy. The lowest level of physical functioning for most women was during the second and third trimesters, and those periods were significantly worse than 6 weeks after giving birth (mean BASFI of 3.2 during the second trimester and 3.6 during the third vs. 2.6 at 6 weeks post partum). Similarly, patients reported overall worse general health during the second and third trimesters, compared with 6 weeks after giving birth, based on RAND-36 scores (mean physical functioning score of 63.1 in the second trimester and 54.5 in the third vs. 71.0 at 6 weeks post partum).

Use of nonbiologic medications remained relatively stable during pregnancy, while biologic disease-modifying antirheumatic drug (DMARD) use (all tumor necrosis factor [TNF] inhibitors) dropped significantly when pregnancy was confirmed. About 20% used NSAIDs during pregnancy, except for during the third trimester when use decreased to 8%. Prednisolone use remained stable at 5%-8%. A total of 11% had used synthetic DMARDs prior to pregnancy, and this rate stayed at 10%-16% during the three trimesters. Overall, 44% had used a biologic DMARD (TNF inhibitor) prior to pregnancy, but this declined sharply to 6% during the first trimester and 1% in the third.

The main limitations of the study included not having data from all of the women for all the time points. In fact, only 22% were included prior to conceiving, which could suggest that women with low disease activity were less likely to visit their rheumatologist, thereby biasing the sample toward an overestimated disease activity at preconception that could have potentially hidden a “more evident deterioration between the preconception visit and the second trimester,” the authors said.

“Future research on pregnancy in women with axSpA should differentiate between subgroups of the disease and aim to include objective assessment of inflammation.”

The study was funded by the Research Fund of the Norwegian Organization for People With Rheumatic Diseases. None of the authors had any conflicts of interest to declare.

ilacy@mdedge.com

SOURCE: Ursin K et al. Rheumatology. 2018 Mar 14. doi: 10.1093/rheumatology/key047.

Axial SpA disease activity remains mostly stable throughout pregnancy