Disease Activity and Rate and Severity of Flares during Peripartum Period in Thai Patients with Systemic Lupus Erythematosus: An Age at Diagnosis and Disease Duration Matched Controlled Study

Abstract

Background/Objective The aim of this study was to compare disease activity and rate and severity of flares between pregnant and nonpregnant systemic lupus erythematosus (SLE) patients. Methods Medical records of pregnant SLE patients seen between January 1993 and June 2017 were reviewed. Nonpregnant SLE controls were matched by age at diagnosis and disease duration before pregnancy. Systemic lupus erythematosus disease activity and flares were determined by the cSLEDAI (clinical Systemic Lupus Erythematosus Disease Activity Index) and Safety of Estrogens in Lupus Erythematosus National Assessment-SLEDAI Flare Index, respectively. Disease activity was measured from 6 months before conception (-6 months) until the postpartum period. The repeated measures mixed model, Cox regression, and cumulative hazard plots were used for statistical analysis. Results Ninety pregnancies occurred in 77 patients. The cSLEDAI scores from -6 months to the postpartum period were comparable between the pregnancy and control group, but slightly yet significantly higher in the controls at conception (mean ± SEM, 3.57 ± 0.45 vs 1.90 ± 0.36; p = 0.019). When compared with the controls, during the pregnancy and postpartum period, the pregnancy group did not have significantly higher incidence of flare (41.11% vs 28.89%, p = 0.086 and 7.78% vs 11.11%, p = 0.445, respectively) or flare category (severe flare) (75.68% vs 53.85%, p = 0.070 and 85.71% vs 70.00%, p = 0.603, respectively). The flare incidence rate (95% confidence interval)/100 patient-months in the pregnancy and control group was 6.75 (4.89-9.32) and 4.34 (2.96-6.38), respectively, giving the adjusted hazards for flare (95% confidence interval) of 1.54 (0.91-2.61) (p = 0.110). Conclusions There was no overall significant increase in SLE disease activity, flare incidence, and flare severity in pregnant SLE patients when compared with their properly matched nonpregnant SLE controls.