Neuromyelitis Optica Spectrum Disorder: Pregnancy-related Attack and Predictive Risk Factors

Objectives: To investigate the influence of pregnancy on patients with neuromyelitis optica spectrum disorder (NMOSD) and to identify risk factors that predict pregnancy-related attack.

Methods: From January 2015 to April 2019, 418 female patients with NMOSD were registered at Huashan Hospital. We retrospectively reviewed their medical records and identified 110 patients with 136 informative pregnancies, of whom 83 were aquaporin-4 antibody (AQP4-ab)-positive and 21 were myelin oligodendrocyte glycoprotein-antibody-positive. Pregnancy-related attack was defined as an attack that occurred during pregnancy or within 1 year after delivery/abortion. We compared annualised relapse rate (ARR) during 12 months before pregnancy with that during every trimester of pregnancy and after delivery/abortion. Multivariate analyses were used to explore the independent risk factors involved and a nomogram was generated for the prediction of pregnancy-related attack. Thirty-five female patients from 3 other centres formed an external cohort to validate this nomogram.

Results: ARR increased significantly during the first trimester after delivery (p<0.001) or abortion (p=0.019) compared with that before pregnancy. Independent risk factors predicting pregnancy-related attack included age at delivery/abortion (20-26.5, p=0.018; 26.5-33, p=0.001), AQP4-ab titre (≥1:100, p=0.049) and inadequate treatment during pregnancy and postpartum period (p=0.004). The concordance index of nomogram was 0.87 and 0.77 using bootstrap resampling in internal and external validation.

Conclusions: The first trimester post partum is a high-risk period for NMOSD recurrence. Patients with younger age, higher AQP4-ab titre and inadequate treatment are at higher risk for pregnancy-related attack.