First trimester screening cut-offs for noninvasive prenatal testing as a contingent screen: Balancing detection and screen-positive rates for trisomy 21.

OBJECTIVE: To provide data on how screen-positive and detection rates of first trimester prenatal screening for fetal Down syndrome vary with changes in the risk cut-off and maternal age to inform contingency criteria for publicly funded noninvasive prenatal testing. MATERIALS AND METHODS: First trimester screening and diagnostic data were collected for all women attending for first trimester fetal aneuploidy screening in Western Australia between 2005 and 2009. Prenatal screening and diagnostic data were linked to pregnancy outcomes, including data from the Midwives' Notification System and the Western Australian Registry of Developmental Anomalies. The prevalence of Down syndrome and performance of screening by risk cut-off and/or for women >35 years were analysed. RESULTS: The current screening risk cut-off of 1:300 has screen-positive and detection rates of 3.5% and 82%. The screen-positive rate increases by 0.7-0.8% for each 100 point change in risk, up to 19.2% at 1:2500 (96% detection rate). Including all women >35 years as screen positive would increase the screen-positive rate and detection rates to 30.2% and 97.2%. CONCLUSION: Variation in screening risk cut-off and the use of maternal age to assess eligibility for noninvasive testing could significantly impact the demand for, and cost of, the test. A contingent first trimester screening approach for risk assessment is superior to the use of a combination of screening and maternal age alone. These data will inform decisions regarding the criteria used to determine eligibility for publicly funded noninvasive prenatal testing.

Folate status in Aboriginal people before and after mandatory fortification of flour for bread-making in Australia.

BACKGROUND: Mandatory fortification of wheat flour for bread-making was introduced in Australia in September 2009, to assist in the prevention of neural tube defects (NTD). NTD are twice as common in Aboriginal compared with non-Aboriginal infants, and folate levels are lower in the Aboriginal population. AIMS: This study was undertaken to compare folate status and NTD in the Aboriginal population before and after fortification. METHODS: Postfortification, 95 Aboriginal men and nonpregnant women aged 16-44 years in metropolitan and regional Western Australia (WA) completed a rapid dietary assessment tool and had blood taken to measure red cell folate. Measures were compared with prefortification values obtained in an earlier study using the same methods. Data on NTD in Aboriginal infants were obtained from the WA Register of Developmental Anomalies. RESULTS: No participant was folate deficient. The mean red cell folate increased after fortification to 443 ng/mL for males and 567 ng/mL for females. The mean difference between red cell folate after fortification compared with before was 129 ng/mL for males (95% CI 81-177); t = 5.4; P < 0.0001) and 186 ng/mL for females (95% CI 139-233); t = 7.9; P < 0.0001). Most participants ate fortified shop-bought bread at least weekly, resulting in an estimated additional folate intake per day of 178 (males) and 145 (females) dietary folate equivalents. NTD prevalence fell by 68% following fortification (prevalence ratio 0.32 (CI 0.15-0.69)). CONCLUSIONS: The population health intervention of mandatory fortification of wheat flour for bread-making has had the desired effect of increasing folate status and reducing NTD in the Australian Aboriginal population.

Baseline investigations of folate status in Aboriginal and non-Aboriginal West Australians prior to the introduction of mandatory fortification.

OBJECTIVE: In September 2009, Australia implemented mandatory folic acid fortification of wheat flour for bread-making to reduce the incidence of neural tube defects. Our study aimed to establish baseline folate status data in Aboriginal and non-Aboriginal Western Australians. METHODS: Patients who presented at a health service or collection centre for blood tests were invited to participate. One hundred and ninety-one Aboriginals and 159 non-Aboriginals were recruited between April 2008 and September 2009. Participants completed a five-minute questionnaire and had blood taken for red blood cell (RBC) folate and serum vitamin B12. Data were analysed using SPSS (version 17.0.2, SPSS Inc., Chicago, IL, USA). RESULTS: Ten per cent (95% confidence intervals (CI): 5, 19) of the Aboriginal women participants and 26% (95% CI: 16, 40) of men had RBC folate concentrations below 250 ng/mL, the cut-off associated with folate deficiency. None of the non-Aboriginal women (95% CI: 0, 4) and 4% of the non-Aboriginal men (95% CI: 2, 12) had RBC folate concentrations below 250 ng/mL. All participants were vitamin B12 replete. None of the 96 Aboriginal and 8% of non-Aboriginal women aged 16-44 reported consumption of supplements with a daily intake of >400 µg folic acid during the previous week. CONCLUSIONS AND IMPLICATIONS: This study established a baseline of RBC folate, folate consumption and supplement use in Aboriginal and non-Aboriginal groups. We identified 10% of Aboriginal women and none of non-Aboriginal women participants with low folate concentrations. The higher prevalence of folate deficiency in Aboriginal participants suggests they are more likely to benefit from a universal program of folate fortification.