By launching Precision Newborn Screening in January 2018 the ultimate goal was to improve the test as stated by Prof Chris Vorster, Director at The Centre for Human Metabolomics from North West University, below:
“The transition to Precision Newborn screening in collaboration with Mayo Clinic in the US is advantageous to our stakeholders and clients. Some of the advantages which will be realised over the next two years are:
- Allowance for sample collection as early as 24 hours after birth, this is beneficial to a large number of clients as the babies will be screened prior to discharge from hospital.
- A decrease in the rate of requests for repeat sampling to near 0%. The current incidence of request for repeats is a great burden to all involved, even to those with a normal screen, since the cost of repeat testing has to be incorporated into the total cost of the service.
- A false positive rate that is substantially below 1%. Currently the cost of false positives is a great barrier to the expansion of the programme. Once this cost becomes negligible, the threshold for implementing additional testing, is much easier to attain. This could result in substantial expansion of the programme.
- Meticulous planning of reflex- and confirmatory testing that will ensure timeous and accurate intervention. In addition, this will create an opportunity to offer the complete service at a once off fee.”
Stats have been compiled, comparing test results from last 6 months of 2017 to the first 6 months of 2018 to determine the impact of the new Precision Newborn Screening Testing Methodology on the false positive rate.
July – December 2017
- 1568 tests were done, 177 abnormal results were received. This gave a False Positive Rate of 11%, over the 6 months. (Which was in keeping with the anticipated False Positive Rate at the time).
- 117 repeat Newborn Screening (dry spot card) tests were done. 98 repeat tests came back as normal.
- 18 results were still abnormal:
- 11 tests recommended additional serum and urine tests to be done and sent to the Potchefstroom Laboratory for Inborn Errors of Metabolism (PLIEM).
- 7 clients were referred for a 3rd dry blood spot card test:
- 5 results were normal
- 2 clients chose not to do the 3rd test, therefore final outcome is unknown.
January – June 2018
- 1936 tests were done and 123 abnormal results were received. The False Positive Rate during these 6 months of testing was 6.3%. This is a clear indication that the Precision Testing is more accurate and is clearly reducing the False Positive Rate.
- 78 repeat tests done. 66 results came back normal (6 results still outstanding).
- 5 abnormal results:
- 2 results recommended additional serum and urine tests to be done and were sent to *PLIEM for testing (Potchefstroom Laboratory for Inborn Errors of Metabolism)
- 1 baby passed away (not metabolic disease related)
- 2 Metabolic diseases diagnosed. Galactosaemia and Biotinidase Deficiency, both babies are doing well on prescribed treatment.
June 2019 – December 2018
Tests done:- 2143
4 tests with no result due to sample collection done too early (before 24 hours after birth – tests repeated at no additional cost to the parents within the correct testing time frame (24- 72 hours) after birth , result normal
Abnormal results requiring repeat Newborn Screening test (dry blood spot card) – 167
- 121 repeat dry blood spot card tests done (46 Repeat tests not done due to parents and / or paediatricians choosing not to do so
- 9 abnormal that did repeats tests – 3 diagnoses made
- Biotinidase deficiency
- 3- Methyl crotonyl COA Carboxylase Deficiency
January 2019 – August 2019
Test done : 2537
Abnormal results requiring repeat Newborn Screening test (dry blood spot card) – 182
- 126 repeat dry blood spot card tests done (55 Repeat tests not done due to parents and / or paediatricians choosing not to do so & 1 baby passed away before repeat could be done (diagnosis of Ornithine Transcarboxylase Deficiency)
- 12 abnormal that did repeat tests – 3 diagnoses made
- Congenital Hypothyroidism x2
*PLIEM results are not sent to FirstScreen, these results are sent directly to the Paediatrician, thus it is difficult to give accurate feedback on the outcome of these tests.
We are looking forward to this rate decreasing even further.