Adverse pregnancy outcomes in hypertensive patients: predictive value of protein concentration versus total protein

To compare the predictive value of protein concentration in a twenty-four hour urine collection to the conventional total protein in a twenty-four hour urine collection for adverse pregnancy outcomes in hypertensive patients.

Retrospective cohort study. Hypertensive patients ≥20 weeks estimated gestational age (EGA) who completed twenty-four hour urine protein collections were identified; antepartum and delivery data were examined. For study patients who met criteria for adverse pregnancy outcome, multi-variable analysis was performed and summary receiver operating characteristic (ROC) curves were generated for each model (total protein compared to protein concentration). The models were compared by analyzing the area under the curve (AUC).

A total of 150 patients were analyzed. Mean gestational age at delivery was 36.7 weeks. Analysis of the ROC curves showed no significant difference between the models (AUCs of 0.668 versus 0.656, p = 0.715). Optimal thresholds were 299.2 mg for total protein and 0.1 mg/ml for protein concentration.

A protein concentration of 0.1 mg/ml on a twenty-four hour urine collection appears equivalent to the traditional 300 mg total protein. If confirmed by prospective studies, this finding would be clinically important in cases where collections fall short of the 300 mg threshold but exceed the 0.1 mg/ml concentration.