6430 Point of care vitamin-D testing as part of the antenatal pathway – a precautionary tale

Objectives Background: Neonatal bone health is dependent on antenatal Vitamin D status.1–4 We have high levels of antenatal deficiency (VDD) in our population.1 Timely identification and correction are important to prevent neonatal rickets and hypocalcaemic seizures.2 4 Since October 2020, our hospital maternity policy has supported screening of all pregnant women at booking to identify and correct for Vitamin D deficiency/insufficiency; deficient levels defined as 50 nmol/l.5 For deficient women there is a clear treatment pathway; local audits indicate that some 65% eligible pregnant women have not received treatment. Reasons include time-lags between testing-and-actioning results (2–3 weeks), failure of patients to return for prescriptions, or administrative issues with follow-up visits organisation. Objective: Establish accuracy of Vitamin-D finger-prick point of care test (POCT),6 for use at first antenatal booking appointment, to facilitate time efficient supplementation advice and prescription, if indicated,5 for patient. Methods Vitamin-D POCT6 compared with gold standard liquid chromatography tandem mass spectrometry 25-hydroxyvitamin D assay. Ethics approval not required as laboratory samples sent for vitamin D analysis in the laboratory were anonymised and used for analysis. Ante-natal (n=7) and two non-pregnant women samples were run as per usual protocol in the laboratory and VHC-POCT vitamin D analyser. External quality assurance (EQA) and quality control (QC) samples also run on both analysers. Dataset reviewed for clinical management impact of acting on levels from POCT vitamin D analyser. Results Graph above demonstrates variation between POCT and Gold standard assay R2 = 0.592); Data-points 7 pregnant, 2 non-pregnant, 3 EQA samples. Five of the seven pregnant patients would have been misclassified if POCT test levels had been used as primary indicator for clinical decision making based on our hospital guidelines5 (table 1). Conclusion Variation between mass spectrometry and POCT vitamin D levels using this specific test is too high for reliable use as a clinical decision support tool. This study reinforces the need for caution and careful test validation, when considering POCTs to enhance clinical care pathways. References McAree T, et al. Matern Child Nutr, 2013. Palacios C, et al. Cochrane Database Syst. Rev, 2019. Tanna NK, et al. Public Health Nutr, 2021. Blair M. BMJ, 2016. London North-West University Healthcare NHS Trust, Drugs page 4. Vitality Health Check Quantitative Vitamin D test (Jungbrunnen – Fountain of Youth GmbH, Germany), Puredent, CE marked. Letters CE appear on European Economic Area traded products implying manufacturer has checked that products meet EU safety, health, environmental requirements. UK regulations – CE marked products can be used in Britain to 01/01/2023, UKCA mark applicable from 01/01/2023.