Authors’ Reply: Reassessing Postpartum Kidney Risk after Preeclampsia: Hidden Burden and Missed Opportunities for Detection

We thank Chen and Lin1 for their interest in our JASN study.2 We selected a urine albumin-creatinine ratio (UACR) threshold of >300 mg/g because our primary focus was severe albuminuria as a clinically meaningful end point, and at the time, major guidelines provided strong recommendations for sodium-glucose cotransporter 2 inhibitors in this risk stratum.3 We agree that moderate albuminuria (A2; 30–300 mg/g) is prognostically meaningful and actionable, particularly in light of recent published data.4 We now reanalyzed our data to include moderate albuminuria. Using a threshold of moderate-to-severe albuminuria (UACR >30 mg/g), the number of incident events increased to 428 among pregnancies complicated by preeclampsia and 3025 among pregnancies without preeclampsia, compared with 113 and 662 events, respectively, using our published definition of severe albuminuria (UACR >300 mg/g). The weighted hazard ratio was 2.17 (95% confidence interval, 1.94 to 2.41). Hopefully, this provides further insight into the burden of early kidney injury in this population. As noted in our manuscript,2 an important limitation is surveillance bias. Within the first postpartum year, only a minority of women underwent serum creatinine or albumin testing; therefore, our absolute incidences should be interpreted as events detected within routine practice rather than definitive estimates of the underlying burden. This is an inherent constraint of analyses based on health care records: Outcomes can only be ascertained when clinicians order testing. In this context, Chen and Lin's comments1 reinforce our conclusion that women who experience preeclampsia would benefit from more systematic postpartum screening, which is likely to identify additional incident cases and create crucial opportunities for timely intervention.