Is the urine spot protein/creatinine ratio a valid diagnostic test for pre-eclampsia?

Abstract

The objective of this study was to assess the value of the spot protein/creatinine ratio as the diagnostic test for pre-eclampsia by correlating it to the 24 h urine protein. For the spot test, this study uses the cut-off value recognised by the International Society for the Study of Hypertension in Pregnancy (ISSHP). Ours was a correlational study made in the setting of the antenatal assessment unit/antenatal ward in a District General Hospital. Patients at >24 weeks' gestation with hypertension and >1+ proteinuria (n = 32) were included in the study. A 10 ml sample of urine was collected for the spot protein/creatinine ratio (PCR) before the 24 h collection was started. Spot PCR samples were stored at –18°C until the end of the study period. The results of the spot PCR were correlated to 24 h results using Pearson's correlation coefficient. Main outcome measures were correlation coefficient, sensitivity, specificity, positive and negative predictive values. Correlation was significant (r2 = 0.82). Sensitivity, 83%; specificity, 92%; positive likelihood ratio, 10.3; negative likelihood ratio, 0.18. The spot PCR correlates well to the 24 h urine protein. The new cut-off values recognised by the ISSHP are producing consistent results. The evidence in favour of the spot PCR needs to be reassessed by larger studies.