MP134
REFLUX NEPHROPATHY AND THE RISK OF PREECLAMPSIA. A SYSTEMATIC REVIEW AND META-ANALYSIS

INTRODUCTION AND AIMS: Background: Reflux nephropathy is the one of the most common urinary tract malformation, and a substantial cause of morbidity in young patients, including women in childbearing age. The follow-up of patients without kidney insufficiency often occurs in a Urology setting. While some recent studies provide information on pregnancy-related outcomes, a systematic, meta-analytic review is not yet available and may help interpreting their heterogeneous results and improve information for counseling.

OBJECTIVE: To analyze pregnancy-related outcomes in literature on reflux nephropathy, to perfect the estimation of the risks and to identify specific research needs.

METHODS: Search strategy: Medline, EMBASE and the Cochrane review databases were searched for the period 2000-2016. The time frame was chosen for limiting the heterogeneity of definitions of pregnancy related outcomes, and of pregnancy care. Selection criteria: We included all studies with at least 6 cases of reflux nephropathy, with or without control groups. Case reports were gathered to look into specific rare occurrences. Data collection and analysis: We extracted data on characteristics of the case series. Analysis was performed in comparison to the provided control group (available only for kidney function). In the absence of a control group of low-risk pregnancies, we employed a large series of low-risk pregnancies available form a multicenter Italian database (the Torino Cagliari Observational Study (TOCOS): 1418 live born singletons in 2000-2015), for the following outcomes: Preeclampsia (PE), pregnancy induced hypertension (PIH), preterm birth, small for gestational age babies. Case reports were analyzed narratively.

RESULTS: The bibliographic search retrieved 2507 papers, of which 11 studies were included: 7 case series and 4 case reports. The series report on 434 women with 879 pregnancies; no study reported on controls. Only two studies reported on kidney function at baseline, without baseline data on proteinuria and hypertension, this limiting the potential conclusions. The case reports uniformly warn against the occurrence of a severe, albeit probably rare complication. Hydro(uretero)nephrosis with or without infection is reported in all 10 cases, occurring most frequently between 20-30 weeks (9/10 cases). This observation suggests the need for ultrasound control of the maternal kidneys, in order to avoid severe complications. Meta-analysis: The meta-analysis showed a significantly higher risk of pregnancy induced hypertension (PIH) (OR 5.55; CI 3.56- 8.66; figure 4C) and PE (OR 6.04; CI 2.41-15.13; figure 4D), with a ten-fold increased risk of hypertensive disorders combined (OR 10.43; CI 6.90-15.75, figure 4E). No difference was observed in preterm delivery and CS, suggesting that the higher incidence of PE is caused by “late-maternal PE”, which has less influence on the first phases of pregnancy. Of note is a higher incidence of stillbirth in compared to low-risk controls, although reported in one paper only.

CONCLUSIONS: Reflux nephropathy is associated with an increased risk of PIH and PE, and not of preterm delivery, suggesting the occurrence of “late- maternal” PE. The finding of a higher incidence of stillbirth demands further analysis.