Should the spot albumin-to-creatinine ratio replace the spot protein-to-creatinine ratio as the primary screening tool for proteinuria in pregnancy?

ObjectivesTo determine the correlation between the spot albumin-to-creatinine (ACR) ratio and protein-to-creatinine ratio (PCR) in pregnancy and if either test is predictive of adverse pregnancy outcome.Study designProspective consecutive cohort study in a single tertiary centre examining 181 patients undergoing proteinuria screening after 20 weeks of pregnancy. A spot PCR and ACR was performed on the first void of the day. Comparison was with linear and logistic regression and ROC curve. Optimal values for the ACR were obtained and compared to a PCR value of 30 mg/mmol with respect to adverse pregnancy outcomes.Main outcome measuresBirth weight <10th centile, preterm birth <32 and <37 weeks, placental abruption, caesarean section, induction of labour, fetal death in utero or neonatal death, Apgar score <5 at 1 min and/or 5 min, pulmonary oedema, sustained blood pressure >170/110 mmHg, magnesium infusion or labetalol infusion during labour.Results254 tests were performed. The ACR and PCR were highly correlated (r = 0.95, p < 0.001) and the area under ROC curve was 0.98. An ACR of 13.4 mg/mmol corresponded to a PCR of 30 mg/mmol. Neither was more predictive of adverse pregnancy outcome nor was the level of proteinuria.ConclusionsThe ACR is not inferior to nor does it perform better than the PCR in screening for proteinuria in pregnancy. Clinicians should use the test with which they are more familiar and may wish to assess local laboratory costs and methods in their selection.