Balancing stringency and feasibility: comparative value of disease-activity measures to predict pregnancy outcomes in systemic lupus erythematosus

Objective To compare preconception disease-activity indices—systemic lupus erythematosus Disease Activity Score low disease activity (SLE-DAS LDA), lupus low disease activity state (LLDAS) and SLE-DAS remission—with Definitions of Remission in SLE (DORIS) remission in predicting adverse maternal and fetal outcomes among pregnant women with SLE. Methods This retrospective cohort study included 202 pregnancies in 196 women with SLE managed at Shenzhen People’s Hospital between January 2017 and December 2024. Preconception disease activity was categorised using SLE-DAS, LLDAS and DORIS remission criteria. Main outcomes were maternal flares and fetal outcomes, including spontaneous abortion, therapeutic abortion, total fetal loss, preterm delivery and small for gestational age (SGA). Predictive accuracies of indices were compared. Results Preconceptionally, 127 pregnancies (62.8%) met LLDAS, 131 (64.9%) met SLE-DAS LDA and 78 (38.6%) achieved DORIS remission. Compared with higher disease activity, SLE-DAS LDA was associated with fewer maternal flares (22.1% vs 45.1%) and therapeutic abortions (6.4% vs 15.7%). LLDAS was associated with lower rates of flare (21.3% vs 45.3%), therapeutic abortion (7.9% vs 17.3%), total fetal loss (19.7% vs 34.2%) and preterm delivery (22.0% vs 25.3%). SLE-DAS and DORIS remission performed similarly for maternal outcomes, while DORIS remission correlated more strongly with favourable fetal outcomes, including lower total fetal loss (15.4% vs 31.5%), preterm delivery (15.4% vs 28.2%) and SGA (9.0% vs 19.4%). Multivariable analyses confirmed that achieving these disease-activity states preconception independently protected against total fetal loss, maternal flare and therapeutic abortion. LLDAS was the best overall predictor, while SLE-DAS LDA was the most attainable and predictive for maternal complications. Conclusion SLE-DAS LDA effectively predicts maternal complication, while LLDAS better identifies fetal risk. Remission offers similar protection but is less attainable, suggesting LDA suffices for conception planning. Optimising preconception disease control remains essential and warrants multicentre validation.