A systematic review and meta-analysis comparing protein/creatinine ratio measurements and dipstick urinalysis in predicting significant proteinuria in pregnancy

Abstract

Several authors have described the close correlation between 24-hour protein excretion and the protein/creatinine ratio in a random sample of urine. All studies to date are limited by a small sample size and many describe correlations rather than predictive values of the test. Literature from 1970 to 2002 was identified. Studies were selected if the accuracy of protein/creatinine ratio measurement in predicting total protein excretion was estimated and compared to a reference standard. Study selection, quality assessment and data abstraction, as 2 × 2 tables comparing the diagnostic test with the reference standard was performed independently and in duplicate. Test accuracy was expressed as likelihood ratio (LR). From 1543 citations, 31 were selected and 11 studies were included in the review (seven for dipstick urinalysis and four for protein/creatinine ratio). The studies evaluating protein/creatinine ratios produced a pooled LR+ of 4.87 (95%b CI 3.84–6.17) and an LR− of 0.24 (95% CI 0.19–0.31) for predicting 300 mg/24-hour proteinuria at the 1+ threshold. The studies evaluating visual dipsticks, produced a pooled LR+ of 2.4 (95% CI 2.05–2.81) and an LR− of 0.57 (95% CI 0.51–0.64) for predicting 300 mg/24-hour proteinuria at the 1+ threshold.