Cross-sectional diagnostic accuracy study of self-testing for proteinuria during hypertensive pregnancies: The UDIP study

Objective To determine the accuracy of self-testing for proteinuria during pregnancy. Design Diagnostic accuracy study. Setting Antenatal clinics, maternity assessment units and inpatient wards at three hospital sites. Population or Sample 345 pregnant women. Methods Pregnant women self-tested in-clinic for urinary protein using visually read dipsticks with samples then sent for laboratory estimation of the spot protein-creatinine ratio (PCR) (primary reference test). Secondary index tests included testing by antenatal healthcare professionals and an automated colorimetric reader. Main outcome measures Sensitivity, specificity, negative predictive value, positive predictive value and likelihood ratios were calculated for self-testing (primary index test) along with healthcare professional and colorimetric testing compared to the primary reference test (PCR). Results 335/345 (97%) had sufficient data to be included in the analysis. Self-testing had a sensitivity of 0.71 (95% confidence interval [CI] 0.62-0.79) and a specificity of 0.89 (95% CI 0.84-0.92) compared to PCR. Sensitivity and specificity of testing by healthcare professionals and the colorimetric reader were similar: sensitivity 0.73 (95% CI 0.64-0.80) and 0.78 (95% CI 0.69-0.85), respectively; specificity 0.88 (95% CI 0.82-0.92) and 0.83 (95% CI 0.78-0.88), respectively. Conclusion Pregnant women can visually read a dipstick for urinary protein with similar accuracy to antenatal healthcare professionals. Automated colorimetric testing was not significantly different, in contrast to some previous studies. Self-testing has the potential to form part of a self-monitoring regime in pregnancy.