Assessment of Ankylosing Spondylitis Activity During Pregnancy Using Different Disease Activity Indices
Authors: Krichevskaya O. A. , Gandaloeva Z. M. , Glukhova S. I. , Skripkina I. Yu. , Demina A. B. , Dubinina T. V. 
Published: November 2020

Objective: Assessment of ankylosing spondylitis activity patterns during pregnancy using BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) and ASDAS-CRP (Ankylosing Spondylitis Disease Activity Score — C-Reactive Protein) disease activity indices.

Materials and methods. The prospective study included 36 pregnant women with AS (modified New York AS criteria, 1984). Patients’ mean age was 31.6±4.8 years, mean age at AS onset was 21.8±10.9, and disease duration 134.9±89.3 months. The control group included 30 healthy pregnant women with no history of back pain and arthritis, their mean age was 28.2±4.5 years. In the I trimester of pregnancy 10 (33.3%) As patients experienced back pain, while in the III trimester already 15 (50%) had back pain. Throughout pregnancy, the intensity of back pain in the I, II и III trimesters based on numeric scale was on average 1.9±0.9; 2.1±1.1 and 2.1±0.8. BASDAI and ASDAS-CRP were used to measure disease activity on gestational Weeks 10–11, 20–21 and 31–32. The time of conception BASDAI score was assessed retrospectively at the 1st visit.

Results and discussion. BASDAI mean values at the time of conception and I, II и III trimesters of pregnancy were: 2.3±1.9; 2.8±1.72 (p<0,05 vs month of conception); 3.2±1.9 and 3.3±2.1 respectively. Mean ASDAS-CRP in the I, II и III trimesters were 1.9±0.7; 2.3±0.9 and 2.2±0,8 respectively. There was a trend to CRP increase in the II and III trimesters vs the I: median CRP values in the I, II and III trimesters were 5.7 [1.6; 6.2], 8.0 [2.1; 9.6] and 7.9 [2.0; 9.2] mg/L, respectively. Percentages of patients with high disease activity based on BASDAI scores in the I, II and III trimesters were 30.6; 34.3 and 34.3%; based on ASDAS-CRP — 36.1; 57.5 and 53%, respectively. Throughout pregnancy, BASDAI scores were lower in the control group than in AS patients (p<0.01). However, no differences were found when comparing BASDAI values of AS patients and healthy women with back pain during pregnancy. The level of fatigue did not differ between pregnant women with AS (median 5[3; 7] and 5[3; 6]) and healthy controls (5[3; 8] and 5[4; 6]) in the I and II trimesters, while in the III trimester, fatigue in healthy pregnant women (6[4; 8]) was more pronounced than in AS patients (5[3; 6], p=0.01). Throughout pregnancy, the intensity of back pain in AS patients and healthy pregnant women with back pain did not differ (p<0.05). Median pain intensity in the I, II and III trimesters was 3[2; 4]; 4[3; 5]; 3[2; 6] and 2,5[1; 4]; 3[2; 7]; 4[2; 6], respectively. A high (rs ≥0,7) correlation of all BASDAI components with the index itself in each trimester of pregnancy, except for joint pain in the month of conception, and in the I and III trimesters was established in the group of pregnant women with AS. The control group had quite high correlation (rs >0.7) of fatigue severity with the BASDAI index in the I and II trimesters of pregnancy and moderate correlation (rs >0.53) in the III trimester; as wells as moderate (rs >0.5-0.69) correlation between back pain and BASDAI

Conclusion. A trend towards increasing AS activity based on BASDAI and ASDAS-CRP scores and CRP levels was established for the first half of pregnancy. Later in pregnancy these increased values failed to return to normal until the end of gestation. The percentage of AS patients with highto-moderate disease activity throughout pregnancy was lower based on BASDAI score vs based on ASDAS-CRP. Some BASDAI components (fatigue and back pain) reflect not only the activity of AS, but also changes associated with physiological pregnancy. The BASDAI index requires adaptation for use in pregnancy