Clinical value and cost analysis of the sFlt-1/PlGF ratio in addition to the spot urine protein/creatinine ratio in women with suspected pre-eclampsia: PREPARE cohort study

BACKGROUND: This study investigated the clinical value of adding the sFlt-1/PlGF ratio to the spot urine protein/creatinine ratio (PCr) in women with suspected pre-eclampsia. METHODS: This was a prospective cohort study performed in a tertiary referral centre. Based on the combination of PCr (< 30) and sFlt-1/PlGF (≤38) results, four groups were described: a double negative result, group A−/−; a negative PCr and positive sFlt-1/PlGF, group B−/+; a positive PCr and negative sFlt-1/PlGF, group C+/−; and a double positive result, group D+/+. The primary outcome was the proportion of false negatives of the combined tests in comparison with PCr alone in the first week after baseline. Secondary, a cost analysis comparing the costs and savings of adding the sFlt-1/PlGF ratio was performed for different follow-up scenarios. RESULTS: A total of 199 women were included. Pre-eclampsia in the first week was observed in 2 women (2%) in group A−/−, 12 (26%) in group B−/+, 4 (27%) in group C+/−, and 12 (92%) in group D+/+. The proportion of false negatives of 8.2% [95% CI 4.9–13.3] with the PCr alone was significantly reduced to 1.6% [0.4–5.7] by adding a negative sFlt-1/PlGF ratio. Furthermore, the addition of the sFlt-1/PlGF ratio to the spot urine PCr, with telemonitoring of women at risk, could result in a reduction of 41% admissions and 36% outpatient visits, leading to a cost reduction of €46,- per patient. CONCLUSIONS: Implementation of the sFlt-1/PlGF ratio in addition to the spot urine PCr, may lead to improved selection of women at low risk and a reduction of hospital care for women with suspected pre-eclampsia. TRIAL REGISTRATION: Netherlands Trial Register (NL8308). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12884-022-05254-1.