Evaluation of a New Laboratory Protocol for Newborn Screening for Congenital Adrenal Hyperplasia in New Zealand.

Between 2005 and 2021, 49 cases of classical congenital adrenal hyperplasia were diagnosed in New Zealand, 39 were detected in newborns and 10 were not detected by screening. Currently, for every case of CAH detected by screening, 10 false-positive tests are encountered. Second-tier liquid chromatography-tandem mass spectrometry (LCMSMS) has the potential to improve screening sensitivity and specificity. A new laboratory protocol for newborn screening for CAH was evaluated. Birthweight-adjusted thresholds for first- and second-tier 17-hydroxyprogesterone, second-tier 21-deoxycortisol and a steroid ratio were applied to 4 years of newborn screening data. The study was enriched with 35 newborn screening specimens from confirmed CAH cases. Newborn screening was conducted on 232,542 babies, and 11 cases of classical CAH were detected between 2018 and 2021. There were 98 false-positive tests (specificity 99.96%, PPV = 10.1%) using the existing protocol. Applying the new protocol, the same 11 cases were detected, and there were 13 false-positive tests (sensitivity > 99.99%, PPV = 45.8%, (X2 test p < 0.0001). Incorporating the retrospective specimens, screening sensitivity for classical CAH was 78% (existing protocol), compared to 87% for the new protocol (X2 test p = 0.1338). Implementation of LCMSMS as a second-tier test will improve newborn screening for classical CAH in New Zealand.

Pulse oximetry screening in a midwifery-led maternity setting with high antenatal detection of congenital heart disease.

AIM: To assess local and individual factors that should be considered in the design of a pulse oximetry screening strategy in New Zealand's midwifery-led maternity setting. METHODS: An intervention study was conducted over 2 years. Three hospitals and four primary maternity units participated in the study. Post-ductal saturation levels were measured on well infants with a gestation of ≥35 weeks. Infant activity and age (hours) at the time of the test were recorded. RESULTS: Screening was performed on 16 644 of 27 172 (61%) eligible infants. The age at which the screening algorithm was initiated varied significantly among centres. The probability of achieving a pass result (saturations ≥95%) in the context of no underlying pathology ranged from .94 for an unsettled infant screened <4 hours of age to .99 (P < .001) when the test was performed after 24 hours on a settled infant. Forty-eight (0.3%) infants failed to reach saturation targets: 37 had significant pathology of which three had cardiac disease. CONCLUSION: Screening practices were influenced by the setting in which it was undertaken. Infant activity and age at the time of testing can influence saturation levels. Screening is associated with the identification of significant non-cardiac pathology.

Feasibility study assessing equitable delivery of newborn pulse oximetry screening in New Zealand's midwifery-led maternity setting.

OBJECTIVES: The aim of this study was to conduct New Zealand-specific research to inform the design of a pulse oximetry screening strategy that ensures equity of access for the New Zealand maternity population. Equity is an important consideration as the test has the potential to benefit some populations and socioeconomic groups more than others. SETTING: New Zealand has an ethnically diverse population and a midwifery-led maternity service. One quaternary hospital and urban primary birthing unit (Region A), two regional hospitals (Region B) and three regional primary birthing units (Region C) from three Health Boards in New Zealand's North Island participated in a feasibility study of pulse oximetry screening. Home births in these regions were also included. PARTICIPANTS: There were 27 172 infants that satisfied the inclusion criteria; 16 644 (61%) were screened. The following data were collected for all well newborn infants with a gestation age ≥35 weeks: date of birth, ethnicity, type of maternity care provider, deprivation index and screening status (yes/no). The study was conducted over a 2-year period from May 2016 to April 2018. RESULTS: Screening rates improved over time. Infants born in Region B (adjusted OR=0.75; 95% CI 0.67 to 0.83) and C (adjusted OR=0.29; 95% CI 0.27 to 0.32) were less likely to receive screening compared with those born in Region A. There were significant associations between screening rates and deprivation, ethnicity and maternity care provider. Lack of human and material resources prohibited universal access to screening. CONCLUSION: A pulse oximetry screening programme that is sector-led is likely to perpetuate inequity. Screening programmes need to be designed so that resources are distributed in the way most likely to optimise health outcomes for infants born with cardiac anomalies. ETHICS APPROVAL: This study was approved by the Health and Disability Ethics Committees of New Zealand (15/NTA/168).