Back pain and assessment of ankylosing spondylitis activity during gestation: symptoms reflecting exacerbation of the disease and pregnancy

Abstract

Objective: to study the dynamics of back pain severity and the frequency of its individual components, characterizing the inflammatory and mechanical rhythm, on the background of gestation in women with ankylosing spondylitis (AS) and compare them with manifestations of dorsopathy in healthy pregnant women; to determine the information value of BASDAI during pregnancy, i.e. to identify its components with the optimal sensitivity and specificity ratio for assessing AS activity during gestation.Patients and methods. The main group consisted of 49 pregnant women with AS who met the modified New York criteria of 1984. The average age of patients was 31.7±4.9 years, the average duration of the disease was 134.4±85.8 months. BASDAI for trimesters of pregnancy was: 2.3 [1.2; 4.4], 2.8 [1.4; 4.2] and 2.2 [1.6; 4.0]. The control group included 51 pregnant women with back pain associated with gestation, without rheumatic diseases. The average age was 28.0±4.4 years. The intensity of back pain was assessed on a numerical rating scale. ROC-analysis was performed with calculation of the area under the curve (AUC) of each component of BASDAI in each pregnancy trimester.Results and discussion. More than 80% of pregnant women with AS experienced back pain, while the intensity of general back pain did not differ from that in the control group. Night back pain with improvement on awakening in the main group was present in 70%, 58% and 68.8% of women, respectively, in the I-III trimesters; its intensity was 3 [1; 5], 3.5 [3; 6] and 3.4 [2; 5] respectively; the frequency and severity of night pain were higher than in the control group. The number of women with improvement after exercise in the II and III trimesters did not differ in both groups. In the second half of pregnancy, 40% of AS patients noted improvement during rest, 52.1% – increased pain after exercise; the frequency of mechanical rhythm pain elements remained lower than in the control group. The AUC value for BASDAI in the first trimester was 0.74; AUC of all BASDAI components was >0.5. In the II and III trimesters, the AUC values for fatigue and back pain were 0.8.Conclusion. During pregnancy the vast majority of women with AS experience back pain, the nature of which changes in the second half of gestation. Night pain that improves on awakening reflects AS activity and is not related to pregnancy. The BASDAI components of severity and duration of morning stiffness have the highest classification value during pregnancy.