Management of pregnancies with suspected preeclampsia based on 6-hour vs 24-hour urine protein collection—a randomized double-blind controlled pilot trial

BACKGROUND: Traditionally, the diagnosis of preeclampsia requires elevated blood pressure measurements and proteinuria demonstrated in a 24-hour urine collection. This prolonged urine collection is associated with patient discomfort, a delay in diagnosis, and in some cases, hospitalization for further management of outcomes. OBJECTIVE: We aimed to assess the feasibility, reliability, and association between maternal and neonatal outcomes of pregnancies managed according to a 6-hour vs 24-hour urine protein collection for suspected preeclampsia. STUDY DESIGN: This was a randomized controlled trial conducted at a tertiary university hospital between January 2019 and January 2021 (ClinicalTrials.gov Identifier: NCT03724786). Patients who were hospitalized for preeclampsia workup were asked to participate and randomized at a 1:1 ratio to 6- and 24-hour urine protein collection groups. Both groups collected urine for 24 hours, during which the collection was also tested after 6-hours. After 24 hours, both results were reviewed by one of the research staff, and either the 6- or 24-hour collection result was reported to the patient's managing physician and was documented in the patient's medical record. Both patient and the managing physician were blinded to group allocation. Unblinding was undertaken in cases of a discrepancy between the results (1 of 2 results of >300 mg protein), and the results were analyzed by intention to treat. The primary study outcome was defined as a composite of adverse maternal outcomes. The sample size was set empirically as per proof on concept design. RESULTS: During the study period, 115 patients participated in the trial, 101 of whom completed the follow-up and were analyzed—51 in the 6-hour group and 50 in the 24-hour group. Patient demographics were similar between the study groups. Unblinding occurred in 7 cases in the 6-hour group, in which the initial 6-hour result ranged from 168 to 475 mg. The rates of composite adverse maternal outcomes were 15.6% and 12.0% in the 6- and 24-hour groups, respectively (P=.59). No significant difference was demonstrated in the rate of adverse neonatal outcomes, cesarean delivery, induction of labor, gestational age at delivery, betamethasone treatment, or neonatal birthweight. CONCLUSION: Managing pregnancies suspected of preeclampsia with a 6-hour urine protein collection is feasible and associated with similar maternal and neonatal outcomes. In cases where the 6-hour result is in the 168 to 475 mg range, we propose completing a 24-hour collection.