SAT0335 CLINICAL COURSE OF ANKYLOSING SPONDYLITIS (AS) IN PREGNANCY: INTERIM DATA FROM PROSPECTIVE STUDY
Authors: Olga Krichevskaya, Zuleykhan Gandaloeva, Anastasiya Demina, Tatiana Dubinina
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Objectives</h3> To study the dynamics of clinical signs, AS activity and patients' functional status during gestation. <h3>Methods</h3> 19 pregnant females with confirmed AS based on modified NY criteria (1984) were included. Patients' mean age was 32,2±1,1y., mean age at AS onset was 22,6±3,1 y., mean disease duration was 147±20,7 months. Control visits were scheduled at 10-11, 20-21 and 31-32 weeks of pregnancy. BASDAI and ASDAS-CRP calculators were used to assess AS activity, while patients' functional status was assessed using BASFI and BASMI scores, and MASES score was used for evaluation of enthesitis. <h3>Results</h3> Pregnancy outcomes included 18 full-term births at 37,6±1,1 weeks of gestation, and a non-developing pregnancy at 18 weeks in one case. Newborns' weight – 3518±67 g. Inflammatory low back pain at conception was reported by 78,9% of participants with mean pain intensity 2,2±0,4 scores by NRS. Pain during pregnancy was observed in 95% of all patients, its' intensity increased by the II trimester (4,6±0,7) and persisted at the same level in the III trimester (<i>p</i>&lt;0,05 between conception and II &amp; III trimesters). Patients reported changing pain patterns by the III trimester: 55,5% noticed pain improvement at rest, and 61,1% indicated exacerbation of pain after physical exercise. Enthesitis rates and intensity were also increasing in the course pregnancy: MASES score was higher in the III trimester (2,3±0,5) vs I trimester (0,4±0,22, <i>p</i>&lt;0,05). Meanwhile the rates of AS others non-axial and non-skeletal manifestations were not changing during gestation. BASDAI score was increasing from the moment of conception (1,7±0,3) until the II trimester (3,3±0,5, p&lt;0,05), staying thereafter at the same level in the III trimester. Multivariate regression revealed BASDAI score (R<sup>2</sup>=0,7) and low back pain (R<sup>2</sup>=0,9) at conception, as well as biological therapy at 3 months prior to conception (R<sup>2</sup>=0,7) as orchestrated predictors of relevant BASDAI score in III trimester. During all pregnancy the BASDAI score was predetermined by assemblage of low back pain intensity (β=0,6), fatigue (β=0,6), and enthesitis-associated pain (β=0,3). Increasing fatigue (by 68,5%), and low back pain (by 24,1%) generated BASDAI score increment by the end of the I trimester. While during the II trimester further increase in BASDAI score was provided by exacerbation of enthesitis (30,7% increment), and back pain (27% increment). ASDAS-CRP score was relatively stable with some trend to increase in the II trimester (2,3±0,3) as compared to baseline at conception (1,7±0,2). CRP also showed some increase in the II the trimester (9,7±2,9 mg/ml) vs I trimester (6,7±2,4 mg/ml, <i>p</i>&gt;0,05). BASMI score insignificantly changed during all 3 trimesters (1,3±0,9; 1,8±0,2; 2,1±0,3 – in I, II and III trimesters, correspondingly). BASFI score showed increase by the III trimester (3,9±0,7) as compared to I trimester (1,4±0,3, p&lt;0,05). Score increase in the III trimester was due to increased AS activity interfering with habitual physical performance, and also due to pregnancy (forward bend, questions 1,2,4). <h3>Conclusion</h3> AS clinical activity increases by the II trimester of pregnancy and persists at moderate and high levels afterwards during all gestation period. AS activity at conception can predetermine AS activity during all pregnancy. 50% of pregnant patients are likely to experience low back pain in the III trimester due to increasing pressure of a growing fetus on the spine. Functional disability increases with progress in pregnancy, being caused in the III trimester by both – AS activity and pregnancy per se. <h3>Disclosure of Interests</h3> None declared