The impact of different classes of lupus nephritis on maternal and fetal outcomes: a cohort study of 147 pregnancies.

Objective: To analyze the impact of different classes of lupus nephritis as risk variables for maternal and fetal adverse outcomes in a cohort of pregnant lupus patients.
Methods: This is a cohort study with retrospective and prospective data collection, conducted at the University Hospital of State University of Rio de Janeiro, Brazil, from 2011 to 2016. A total of 147 pregnancies of 137 systemic lupus erythematosus patients of whom 66 had lupus nephritis were included. Demographic and clinical features, as well as maternal and fetal outcomes were observed for each nephritis histological class among systemic lupus erythematosus patients and compared with those without nephritis. Categorical variables were expressed as absolute and relative frequencies and numerical variables as means and standard deviation. The chi-square test with Fisher's correction and Student's t-test were used for statistical analysis. A pvalue < 0.05 was considered statistically significant.
Results: Systemic lupus erythematosus patients with proliferative nephritis (classes III/IV, n = 54) presented more frequent disease flares ( p = 0.02), continuous active disease during pregnancy and puerperium ( p = 0.006), hospitalization due to systemic lupus erythematosus ( p < 0.001), hospitalization not directly associated to systemic lupus erythematosus ( p = 0.04), higher frequency of cesarean delivery ( p = 0.03) and preeclampsia ( p = 0.01) than patients without nephritis. Permanent damage measured by Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index was more frequent in classes III/IV than among the other patients. The frequency of adverse fetal outcomes such as prematurity and admission to neonatal intensive care unit were not different among systemic lupus erythematosus patients with or without nephritis. However, perinatal deaths were more frequent in patients with all classes of nephritis ( p = 0.003).
Conclusion: Systemic lupus erythematosus patients with proliferative nephritis (classes III/IV) have a higher frequency of adverse maternal outcomes. This is probably due to the major impact of proliferative forms of nephritis on women's global heath, which is corroborated by the higher Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index findings, although we cannot exclude the negative influence of disease activity for the maternal adverse events. The findings indicate a need for further lupus nephritis classification beyond the nonspecific term nephritis in the context of lupus pregnancy as the impact on maternal and fetal outcomes varies according to histological class.