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Abstract
Background Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease, and it primarily affects women of childbearing age. While numerous studies have identified risk factors for fetal loss in pregnant women with SLE, results varied among studies. It is essential and helpful if the clinician is able to predict the risk of fetal loss in pregnant patients with SLE in the early stages of gestation, which can allow special monitoring and treatment as early as possible. However, a few studies have proposed such a predictive model or risk score. We therefore sought to develop a predictive model for fetal loss in women with SLE.
Methods A retrospective observational study of 338 pregnancies with SLE at a tertiary medical center was performed from September 2011 to May 2017, and relevant medical records were reviewed. Multiple gestations and artificial abortions were excluded for personal reasons. A stepwise regression to identify the predictors related to the fetal loss and coefficient B of each variable was used to develop a predictive model and make a corresponding risk classification. The Hosmer-Lemeshow test, Omnibus test and area under the receiveroperating characteristic (ROC) curve (AUC) were used to assess the goodness-of-fit and discrimination of the predictive model. A 10-fold cross validation was used to assess the model for over-fitting.
Results Unplanned pregnancies (OR 2.84, 95% CI=1.12–7.22), C3 hypocomplementemia (OR 5.46, 95% CI=2.30–12.97), and 24 hr-urinary protein level (0.3 protein <1.0 g/24 hour: OR 2.10, 95%CI=0.63–6.95; protein 1.0 g/24 hour: OR 5.89, 95%CI=2.30–15.06) were selected by the stepwise regression. The Hosmer-Lemeshow test resulted in p=0.325; the Omnibus test resulted in p<0.001 and the AUC was 0.829 (95% CI=0.744–0.91) in the regression model. The corresponding risk score classification was divided into low risk (0–3) and high risk groups (>3), with a sensitivity of 60.5%, a specificity of 93.3%, positive likelihood ratio of 9.03 and negative likelihood ratio of 0.42.
Patients’ characteristics during pregnancy
Multivariable analysis of fetal loss
Adjusted odds ratio and B coefficient from cohort with multivariable logistic regression model and corresponding risk score
The risk classification for fetal loss according to the risk score system
Diagonal segments are produced by ties
Score – morbitdity of fetal loss
Conclusions A predictive model for fetal loss in women with SLE was developed using the timing of conception, C3 complement and 24 hr-urinary protein level. This model may help clinicians in identifying women with high risk pregnancies, thereby carrying out monitoring or/and interventions for improving fetal outcomes.
Funding Source(s): The work was supported by funding from Shanghai Municipal Commission of Health and Family Planning (Grant no. 2017ZZ02016 and 15GWZK0701).