Research and analysis

Sickle cell and thalassaemia screening: data report 2019 to 2020

Published 13 April 2022

Applies to England

In this report we use ‘screening year 2019 to 2020’ to refer to 1 April 2019 to 31 March 2020.

1. Executive summary

This report presents screening data for the NHS Sickle Cell and Thalassaemia (SCT) Screening Programme for the screening year 2019 to 2020.

The report contains data submitted by antenatal screening laboratories, genomic laboratories, newborn screening laboratories, and newborn DNA testing laboratories.

Detailed presentation of screening standards data is not included in this report as this is contained within the annual antenatal standards data report.

In screening year 2019 to 2020, the NHS screened around 660,000 pregnant women for sickle cell, thalassaemia and other haemoglobin variants. It also screened around 617,000 newborn babies for sickle cell disease (SCD).

The proportion of pregnant women in England with screen positive results remained stable in screening year 2019 to 2020 compared to previous years. In women with a screen positive result, the most common identified risk to pregnancy was having a baby with a possible sickle cell condition (47% of women with a screen positive result), followed by having a baby with a possible beta thalassaemia condition (35% of women with a screen positive result).

There were 360 prenatal diagnosis (PND) tests performed in screening year 2019 to 2020, a slight increase compared to the previous year. The proportion of PND tests performed at less than or equal to 12 weeks and 6 days gestation decreased slightly in screening year 2019 to 2020 and remained lower than between screening years 2008 to 2009 and 2013 to 2014.

In England in the screening year 2019 to 2020, 1 in 2,517 babies screened for SCD were screen positive for significant conditions, and 1 in 78 were carriers. The rates of babies screening positive for a significant condition decreased slightly in screening year 2019 to 2020 after a slight increase in screening year 2018 to 2019.

The rates of babies screening positive for carrier results has remained stable in London since screening year 2017 to 2018. There is a continuing trend of increases in the rate of declines for newborn screening for SCD with a rate of 6.42 per 1,000 babies in screening year 2019 to 2020. A task and finish group has been set up, which includes both the SCT screening programme and the newborn blood spot (NBS) screening programme, to look into the increase in declines.

2. Methodology

The NHS SCT screening programme has 9 screening standards. Screening standards provide reliable and timely information about the quality of the screening programme across the whole screening pathway. The SCT screening standards are presented in the annual antenatal standards reports.

In addition to the SCT screening standards, some standards within the newborn blood spot (NBS) screening programme are also relevant to the SCT screening programme. These include standards relating to coverage and blood spot test processes, such as timely sample collection. The NBS screening standards are presented in annual reports.

For standards that are also key performance indicators (KPIs), data are presented in the KPI reports.

As the screening standards are presented in the above reports, this report presents data that is additional to the screening standards. The collection of this data is described below.

Timely annual data returns are required from all antenatal and newborn screening laboratories, in line with laboratory guidance and Service Specification no. 18: NHS Sickle Cell and Thalassaemia Screening Programme.

Data is collected using spreadsheet-based data templates. The data is checked on receipt and, if required, the relevant laboratory is contacted for any clarifications that are needed.

Antenatal laboratories are classified as either high prevalence or low prevalence, based on the percentage of booking bloods that are positive at that laboratory. Some graphs are separated by high and low prevalence laboratories, and some are separated by London and the rest of England, as London is a high prevalence area for SCT.

While the screening programme covers only England, screening data is provided by the newborn laboratories in Scotland, Wales and Northern Ireland. However, these countries are not included in ethnicity figures, as Scotland uses different ethnic categories, and Wales and Northern Ireland do not routinely collect ethnicity data for all babies.

The National Congenital Anomalies and Rare Diseases Registration Service (NCARDRS) provides a de-personalised dataset of PND test data to the programme. This data is collected from PND laboratories and verified by NCARDRS.

The 2 newborn DNA testing laboratories in England also submit aggregated data to the programme annually.

3. Antenatal screening and prenatal diagnosis

3.1 Antenatal screening laboratory data quality and completeness

Out of 142 expected antenatal screening laboratory returns, there were 133 received for screening year 2019 to 2020 (93.7% response rate). The deadline date for returns to be submitted was extended from June to September for screening year 2019 to 2020 data due to the impact of the COVID-19 pandemic on services. The expected data returns are based on the maternity providers served by the screening laboratory, and one screening laboratory may serve more than one maternity provider.

Not all laboratories were able to submit data for all requested data fields. Data fields were excluded where providers were unable to submit data. Where exclusions were made, these are identified below the relevant charts and tables.

Some laboratories are unable to match the mother’s results to the biological father’s results and so cannot provide the number of couples where pregnancy is at risk of a clinically significant condition, requiring referral for counselling. As a result, the reported number is likely to be an underestimate of the true number of couples where pregnancy is at risk of a clinically significant condition.

3.2 Numbers screened and detected in antenatal screening

In screening year 2019 to 2020, after data exclusions were applied, there were 616,573 antenatal care bookings reported by the laboratories in the included returns, of which 13,108 were identified as screen positive (approximately 1 in 47 women screened).

Of these women with screen positive results, 771 pregnancies were identified as being at risk of the baby inheriting a clinically significant sickle cell or thalassaemia condition (approximately 1 in 17 women with screen positive results), based on the results of both parents.

These pregnancies are represented by the orange boxes in the breakdown table in the SCT antenatal return form in section 5. They include all pregnancies where there is a 1 in 4 chance or higher of the baby having a clinically significant haemoglobin condition.

While referral for counselling is required for all of these pregnancies, prenatal diagnosis must be offered for the serious conditions, as described in the inheritance risk table within the sickle cell and thalassaemia handbook.

Please note that in editions prior to the 2018 to 2019 report, the ‘at risk’ couples presented in this section were the pregnancies at risk of the more serious haemoglobin conditions only.

Table 1: Numbers screened and detected, England, screening year 2019 to 2020

Region	Returns included/expected†	Antenatal screening samples (n)	Screen positive (n)	Screen positive (% of samples)	Pregnancy at risk‡ (n)	Pregnancy at risk‡ (% of screen positive)
London	24/25	134,584	5,924	4.40	348	5.87
Midlands and East	38/40	190,638	3,397	1.78	193	5.68
North	34/40	157,207	2,134	1.36	139	6.51
South	32/37	134,144	1,653	1.23	91	5.51
England total	128/142	616,573	13,108	2.13	771	5.88

†Expected returns are not included when no data return was received or when exclusions to received data have been made. Received data returns are only included above if data for number of samples, number of screen positives and number of at-risk couples were all accepted. ‡Pregnancy at risk of a clinically significant condition, referral for counselling required.

Table 2: Numbers screened and detected, high prevalence areas, England, screening year 2019 to 2020

Region	Returns included/expected†	Antenatal screening samples (n)	Screen positive (n)	Screen positive (% of samples)	Pregnancy at risk‡ (n)	Pregnancy at risk‡ (% of screen positive)
London	24/25	134,584	5,924	4.40	348	5.87
Midlands and East	17/18	101,298	2,642	2.61	164	6.21
North	10/13	70,342	1,555	2.21	108	6.95
South	7/9	40,132	797	1.99	62	7.78
England total	58/65	346,356	10,918	3.15	682	6.25

†Expected returns are not included when no data return was received or when exclusions to received data have been made. Received data returns are only included above if data for number of samples, number of screen positives and number of at-risk couples were all accepted. ‡Pregnancy at risk of a clinically significant condition, referral for counselling required.

Table 3: Numbers screened and detected, low prevalence areas, England, screening year 2019 to 2020

Region	Returns included/expected†	Antenatal screening samples (n)	Screen positive (n)	Screen positive (% of samples)	Pregnancy at risk‡ (n)	Pregnancy at risk‡ (% of screen positive)
London	0/0	-	-	-	-	-
Midlands and East	21/22	89,340	755	0.85	29	3.84
North	24/27	86,865	579	0.67	31	5.35
South	25/28	94,012	856	0.91	29	3.39
England total	70/77	270,217	2,190	0.81	89	4.06

†Expected returns are not included when no data return was received or when exclusions to received data have been made. Received data returns are only included above if data for number of samples, number of screen positives and number of at-risk couples were all accepted. ‡Pregnancy at risk of a clinically significant condition, referral for counselling required.

In London, the percentage of antenatal screening samples that were screen positive increased slightly in screening year 2019 to 2020 following a small decrease seen in screening year 2018 to 2019 (Figure 1). In the rest of England, the percentage of screen positives has remained stable over recent years.

Figure 1: Women who screen positive as a percentage of antenatal screening samples received by laboratories, England, screening year 2010 to 2011 to screening year 2019 to 2020

Some returns are not included as data was not received or excluded for screening years:

• 2010 to 2011: 3 returns
• 2011 to 2012: 2 returns
• 2012 to 2013: 3 returns
• 2013 to 2014: 2 returns
• 2014 to 2015: 4 returns
• 2015 to 2016: 6 returns
• 2016 to 2017: 10 returns
• 2017 to 2018: 14 returns
• 2018 to 2019: 8 returns
• 2019 to 2020: 13 returns

3.3 Declined antenatal screening tests for sickle cell and thalassaemia

Personal informed choice is an important element of population screening, and as such, screening tests for sickle cell and thalassaemia may be declined for various reasons.

Table 4 shows, after data exclusions, the number of declines of antenatal screening reported by screening laboratories, as a proportion of total antenatal screening samples tested.

A difference in declines reported by maternity services compared to screening laboratories was noted in screening year 2018 to 2019. Work to investigate this has not yet started due to limited capacity within the programme during the COVID-19 pandemic. We hope to begin this work over the next year.

Table 4: Declined antenatal screening by region, England, screening year 2017 to 2018 to screening year 2019 to 2020

Screening year 2017 to 2018

Region	Antenatal screening samples	Declines	% of samples
London	82,840	44	0.05
Midlands and East	191,000	252	0.13
North	162,541	571	0.35
South	134,773	249	0.18
England total	571,154	1,116	0.20

Returns not included as data not received or excluded: 29.

Screening year 2018 to 2019

Region	Antenatal screening samples	Declines	% of samples
London	117,278	37	0.03
Midlands and East	184,896	175	0.09
North	171,495	242	0.14
South	133,167	237	0.18
England total	606,836	691	0.11

Returns not included as data not received or excluded: 19.

Screening year 2019 to 2020

Region	Antenatal screening samples	Declines	% of samples
London	122,515	64	0.05
Midlands and East	182,971	143	0.08
North	163,155	257	0.16
South	119,328	323	0.27
England total	587,969	787	0.13

Returns not included as data not received or excluded: 19.

Figure 2 shows the trends in rates of declines for antenatal screening since screening year screening year 2007 to 2008, broken down by high and low prevalence areas. Reported rates of declines have decreased over time, and the rate in screening year 2019 to 2020 was similar to the rate in screening year 2018 to 2019.

Since screening year 2017 to 2018, rates of declines have been similar across high and low prevalence areas, following a period in which decline rates were consistently higher in low prevalence areas.

Figure 2: Trends in declined antenatal screening as a percentage of antenatal screening samples received by laboratories, England, by prevalence, screening year 2007 to 2008 to screening year 2019 to 2020

Some returns are not included as data was not received or excluded for screening years:

• 2007 to 2008: 40 returns
• 2008 to 2009: 46 returns
• 2009 to 2010: 42 returns
• 2010 to 2011: 18 returns
• 2011 to 2012: 15 returns
• 2012 to 2013: 16 returns
• 2013 to 2014: 15 returns
• 2014 to 2015: 15 returns
• 2015 to 2016: 13 returns
• 2016 to 2017: 18 returns
• 2017 to 2018: 29 returns
• 2018 to 2019: 19 returns
• 2019 to 2020: 19 returns

3.4 Testing of the baby’s biological father

If a woman has a screen positive result, the baby’s biological father should be offered testing to determine the risk to the pregnancy. If the baby’s biological father is not available for testing, it is more difficult to accurately assess the baby’s risk of inheriting sickle cell and thalassaemia. In this situation, women are counselled and offered PND. It is estimated that this group of women accounts for about 24% of women with a screen positive result in screening year 2019 to 2020 (calculated from the number of women with a screen positive result, minus the number of biological father results available).

Figure 3: Trends in uptake of testing of the baby’s biological father, England, by prevalence, screening year 2008 to 2009 to screening year 2019 to 2020

Some returns are not included as data was not received or excluded in screening years:

• 2008 to 2009: 15 returns
• 2009 to 2010: 22 returns
• 2010 to 2011: 7 returns
• 2011 to 2012: 9 returns
• 2012 to 2013: 10 returns
• 2013 to 2014: 11 returns
• 2014 to 2015: 11 returns
• 2015 to 2016: 7 returns
• 2016 to 2017: 11 returns
• 2017 to 2018: 18 returns
• 2018 to 2019: 9 returns
• 2019 to 2020: 15 returns

For figure 3, percentage uptake will include father results known from historical records in line with guidance in the handbook for laboratories.

Uptake of biological father testing is higher in low prevalence areas compared to high prevalence areas. Uptake of biological father testing has increased in high prevalence areas since screening year 2010 to 2011 and is now at about 69%.

Uptake of biological father testing has been variable in low prevalence areas since recording began in screening year 2008 to 2009 but is now at 77%.

There was a slight decrease in uptake between screening years 2018 to 2019 and 2019 to 2020. The biggest increases in uptake have occurred in high prevalence areas. Uptake of testing of the baby’s biological father continued to increase slightly in screening year 2019 to 2020.

Table 5: Uptake of testing of the baby’s biological father, England, screening year 2017 to 2018 to screening year 2019 to 2020

Screening year 2017 to 2018

Region	Father samples requested	Father results available	% uptake
London	5,361	2,947	55.0
Midlands and East	3,580	2,449	68.4
North	2,375	1,681	70.8
South	1,823	1,367	75.0
England total	13,139	8,444	64.3

Returns not included as data not received or excluded: 18. Father samples available includes results known from historical records in line with guidance in the handbook for laboratories.

Screening year 2018 to 2019

Region	Father samples requested	Father results available	% uptake
London	6,041	3,772	62.4
Midlands and East	3,857	2,656	68.9
North	2,484	1,845	74.3
South	1,919	1,587	82.7
England total	14,301	9,860	68.9

Returns not included as data not received or excluded: 9. Father samples available includes results known from historical records in line with guidance in the handbook for laboratories.

Screening year 2019 to 2020

Region	Father samples requested	Father results available	% uptake
London	5,984	3,841	64.2
Midlands and East	3,663	2,647	72.3
North	2,513	1,905	75.8
South	1,941	1,533	79.0
England total	14,101	9,926	70.4

Returns not included as data not received or excluded: 15. Father samples available indicates results known from historical records in line with guidance in the handbook for laboratories.

3.5 Breakdown of pregnancy risk

For women with a screen positive result, the most common identified risk to the pregnancy was the baby having possible sickle cell disease, followed by the baby having possible beta thalassaemia (Table 6).

Based on results of both parents, it can be determined whether the pregnancy is at risk of a haemoglobin condition. Breakdown data is requested on both biological mother and father results to identify the specific risk of having a baby with a haemoglobinopathy condition. This information also allows us to separate sickle cell and thalassaemia screen positive results and to identify cases where the baby’s biological father was not available for testing, or the laboratory is unable to link the results to the mother’s results.

Table A in the accompanying additional information spreadsheet shows the breakdown of the pregnancy risk for screen positive women and a summary is shown in Table 6.

Table 6: Screen positive women, broken down by risk to the pregnancy, England, screening year 2019 to 2020

Risk to pregnancy	Proportion of screen positive women (%)
Baby with possible sickle cell disease	47.4
Baby with possible beta thalassaemia	34.5
Baby with possible alpha thalassaemia	6.9
Other clinically significant results	7.9
Other Hb variants requiring testing of baby’s father	3.4

3.6 Prenatal diagnosis (PND)

Early antenatal screening for SCT is important as this will maximise the opportunity for parents to make a personal informed choice. Where parents choose to have PND, advanced gestational age may limit reproductive choices.

Figure 4 demonstrates that the proportion of PND tests performed ≤ 12⁺⁶ weeks gestation decreased slightly in screening year 2019 to 2020 compared to the previous year and remains lower than in the screening years up to 2013 to 2014.

Figure 4: Proportion of PND tests performed by gestation, England, screening year 2008 to 2009 to screening year 2019 to 2020

PND tests for women from devolved nations that were tested at English laboratories have been excluded.

Table 7: Gestation at PND test, England, screening year 2017 to 2018 to screening year 2019 to 2020

Gestation at PND test	2017 to 2018 n (%)	2018 to 2019 n (%)	2019 to 2020 n (%)
≤ 12+6 weeks	152 (41.5)	147 (43.1)	149 (41.4)
13+0 to 14+6 weeks	88 (24.0)	89 (26.1)	88 (24.4)
≥ 15+0 weeks	125 (34.2)	104 (30.5)	119 (33.1)
Unknown gestation	1 (0.3)	1 (0.3)	4 (1.1)
Total	366 (100.0)	341 (100.0)	360 (100.0)

PND tests for women from devolved nations that were tested at English laboratories have been excluded. Gestation relates to the gestation on the day of fetal sampling.

3.7 Numbers tested and detected in PND testing

There are 4 laboratories in England that undertook genetic analysis of the PND test in screening year 2019 to 2020: King’s College Hospital (KCH), Manchester, Oxford, and University College London Hospital (UCLH). There were 360 PND tests performed in screening year 2019 to 2020, an increase compared to screening year 2018 to 2019.

Figure 5: Number of PND tests performed, by laboratory, England, screening year 2008 to 2009 to screening year 2019 to 2020

PND tests for women from devolved nations that were tested at English laboratories have been excluded.

Table 8: Breakdown of PND fetal results by condition, England, screening year 2017 to 2018 to screening year 2019 to 2020

Fetal result of haemoglobinopathy

PND result	2017 to 2018	2018 to 2019	2019 to 2020
Hb SS	55	46	64
Hb SC	12	7	13
Hb S/Beta thalassaemia	4	5	3
Hb S + other	2	0	1
Alpha thalassaemia	0	2	2
Beta thalassaemia	19	12	16
Other	0	2	2
Total	92	74	101

Fetal result of carrier

PND result	2017 to 2018	2018 to 2019	2019 to 2020
Hb AS	130	112	123
Hb AC	13	10	9
Alpha thalassaemia carrier	6	2	3
Beta thalassaemia carrier	32	27	31
Other Hb carrier	3	2	9
Total	184	153	175

3.8 Fetal result of no abnormality detected (NAD) broken down by PND risk

PND result	2017 to 2018	2018 to 2019	2019 to 2020
Risk for sickle cell	65	86	63
Risk for thalassaemia	12	17	19
Risk for sickle cell/beta thalassaemia	12	8	1
Risk not known	1	3	1
Total	90	114	84

PND tests for women from devolved nations that were tested at English laboratories have been excluded. ‘Other’ includes other haemoglobinopathy variants. ‘Risk not known’ includes cases where no data was provided by the PND laboratory.

3.9 PND results by family origin

Table 9: Number of PND tests by mother’s family origins, England, screening year 2019 to 2020

Mother’s family origin	n	%
African	222	61.7
Asian	33	9.2
European / United Kingdom (White)	27	7.5
Middle Eastern	16	4.4
Caribbean	14	3.9
African-Caribbean	12	3.3
South Asian	5	1.4
Mixed	3	0.8
Unknown	28	7.8
Total	360	100.0

PND tests for women from devolved nations that were tested at English laboratories have been excluded. Mother’s family origin is recorded in data received from PND laboratories. Categories have then been assigned to mother’s family origin based upon the categories used in the family origin questionnaire (FOQ).

The data received from some PND laboratories do not currently always allow African, Caribbean and African-Caribbean family origins to be accurately separated. The programme is taking steps to rectify this so that in future African, Caribbean and African-Caribbean family origins can be reported separately.

3.10 Pregnancy outcomes

One of the aims of the SCT screening programme is to ensure women are given timely information so that they can make a personal informed choice. The screening programme collects data on pregnancy outcomes following PND testing to assess what choices women and couples make following the test.

Due to the COVID-19 pandemic, there is missing data on short term outcomes for 39.2% of PNDs performed in screening year 2019 to 2020. The NCARDRS team were unable to follow up the missing data due to the immense pressure providers faced during the pandemic, therefore outcome data is not shown in this report.

4. Newborn screening for SCD

4.1 Numbers screened and results

Screen positive results for significant conditions comprise:

• baby with fetal and sickle haemoglobins (FS)
• baby with fetal, sickle and C variant haemoglobins (FSC)
• baby with fetal, sickle and other haemoglobins (FS-other)
• baby with fetal and E variant haemoglobins (FE) results

These results indicate the condition is suspected, with further confirmatory testing required to confirm diagnosis.

Carrier results comprise:

• baby with fetal, adult and sickle haemoglobins (FAS)
• baby with fetal, adult and C variant haemoglobins (FAC)
• baby with fetal, adult and D variant haemoglobins (FAD)
• baby with fetal, adult and E variant haemoglobins (FAE)
• other haemoglobin variants.

Table 10: Numbers and rates of significant condition and carrier screening results, newborn blood spot screening for sickle cell disease, United Kingdom, screening year 2019 to 2020

Significant conditions

Region	n	Rate / 1,000	1 in x	Babies tested
London	126	1.03	970	122,270
Midlands and East	62	0.35	2,889	179,148
North	34	0.21	4,820	163,873
South	23	0.16	6,214	142,913
Unknown	0	0.00	0	8,551
England total	245	0.40	2,517	616,755
Scotland	12	0.24	4,139	49,664
Wales†	4	0.14	7,356	29,424
Northern Ireland	1	0.04	22,519	22,519
UK total	262	0.36	2,742	718,362

Carriers

Region	n	Rate / 1,000	1 in x	Babies tested
London	3,473	28.40	35	122,270
Midlands and East	2,056	11.48	87	179,148
North	1,195	7.29	137	163,873
South	1,203	8.42	119	142,913
Unknown	69	8.07	124	8,551
England total	7,996	12.96	77	616,755
Scotland	198	3.99	251	49,664
Wales†	-	-	-	29,424
Northern Ireland	53	2.35	425	22,519
UK total	8,247	11.48	87	718,362

English region is based upon the maternity provider, clinical commissioning group (CCG) or child health information service (CHIS) of the baby. The geography differs according to the submitting laboratory.

Data is based up samples received into newborn screening laboratories in screening year 2019 to 2020, apart from for Wales where data is based on babies tested from the cohort of eligible babies born in screening year 2019 to 2020.

Babies identified to be from the Isle of Man or overseas by newborn screening laboratories have not been included in the above. Portsmouth data includes babies from the Channel Islands and babies born to military families.

† The Wales newborn screening protocol is designed to detect only the disease states of SCD. However, those cases that are identified from the newborn screening process and subsequently determined to be carriers of SCD are referred for follow up.

Table 11: Breakdown of newborn screening results (significant conditions), newborn blood spot screening for sickle cell disease, England, screening year 2019 to 2020

Region	FS	FSC	FS-Other	FE	F Only	Declined	Babies tested	Babies offered screening (tested + declined)
London	79	40	4	3	6	1,591	122,270	123,861
Midlands and East	44	10	0	8	4	807	179,148	179,955
North	23	7	2	2	5	273	163,873	164,146
South	10	6	3	4	1	447	142,913	143,360
Unknown	0	0	0	0	2	447	8,551	8,998
England total	156	63	9	17	18	3,565	616,755	620,320

Region is based on maternity provider, CCG or CHIS of the baby. The geography used differs according to the submitting laboratory.

Babies identified to be from the Isle of Man or overseas by newborn screening laboratories have not been included in the above. Portsmouth data includes babies from the Channel Islands and babies born to military families.

Data is based on samples received into newborn screening laboratories in screening year 2019 to 2020.

Table 12: Breakdown of newborn screening results (carrier conditions), newborn blood spot screening for sickle cell disease, England, screening year 2019 to 2020

Region	FAS	FAC	FAD	FAE	Other	Declined	Babies tested	Babies offered screening (tested + declined)
London	2,359	541	162	394	17	1,591	122,270	123,861
Midlands and East	1,320	308	214	207	7	807	179,148	179,955
North	790	133	137	132	3	273	163,873	164,146
South	773	170	129	130	1	447	142,913	143,360
Unknown	46	11	6	6	0	447	8,551	8,998
England total	5,288	1,163	648	869	28	3,565	616,755	620,320

Region is based on maternity provider, CCG or CHIS of the baby. The geography used differs according to the submitting laboratory.

Babies identified to be from the Isle of Man or overseas by newborn screening laboratories have not been included in the above. Portsmouth data includes babies from the Channel Islands and babies born to military families.

Data is based on samples received into newborn screening laboratories in screening year 2019 to 2020.

Figure 6: Trends in rates of babies identified with a significant condition, England, screening year 2005 to 2006 to screening year 2019 to 2020

Figure 6 shows that the rates of babies screening positive for a significant condition decreased slightly in screening year 2019 to 2020 after a slight increase in screening year 2018 to 2019 in both London and the rest of England. The rate in London has remained fairly stable over the last 5 years following a steady decrease.

Figure 7: Trends in rates of babies with carrier results, England, screening year 2005 to 2006 to screening year 2019 to 2020

Figure 7 shows that the rate of screen positive results for carrier results has steadily decreased in London since reporting began in screening year 2005 to 2006 and has remained stable over the last 3 years. The rate of screen positive results for carrier results in the rest of England has remained stable since reporting began in screening year 2005 to 2006.

4.2 Results by ethnicity

Table 13: Numbers and rates of significant condition screening results by ethnic category, English laboratories, screening year 2019 to 2020

Ethnic category	n	Rate / 1,000	1 in x	Babies tested
White	1	0.00	433,652	433,652
Mixed	16	0.39	2,573	41,170
Asian†	17	0.24	4,214	71,643
Black Caribbean	28	5.17	193	5,412
Black African	156	7.34	136	21,257
Any other Black background	18	4.89	204	3,678
Other†	5	0.28	3,633	18,167
Not stated / Not known	4	0.20	4,929	19,715
England total	245	0.40	2,509	614,694

†’Asian’ includes ‘Indian’, ‘Pakistan’, ‘Bangladeshi’ and ‘Any other Asian background’. ‘Other’ includes ‘Chinese’ and ‘Any other ethnic category’.

Table 14: Numbers and rates of carrier screening results by ethnic category, English laboratories, screening year 2019 to 2020

Ethnic category	n	Rate / 1,000	1 in x	Babies tested
White	751	1.73	577	433,652
Mixed	1,567	38.06	26	41,170
Asian†	1,137	15.87	63	71,643
Black Caribbean	711	131.37	8	5,412
Black African	2,968	139.62	7	21,257
Any other Black background	403	109.57	9	3,678
Other†	230	12.66	79	18,167
Not stated / Not known	233	11.82	85	19,715
England total	8,000	13.01	77	614,694

†’Asian’ includes ‘Indian’, ‘Pakistan’, ‘Bangladeshi’ and ‘Any other Asian background’. ‘Other’ includes ‘Chinese’ and ‘Any other ethnic category’.

Figure 8: Breakdown of babies that screened positive for a significant condition by ethnic category, screening year 2019 to 2020, English laboratories

Ethnic category	% of babies with a screen positive result
Black African	37.9
Mixed	19.2
Asian†	14.0
White	9.1
Black Caribbean	9.0
Any other Black background	5.1
Not stated / Not known	2.9
Other†	2.9

Data in Figure 8 includes all babies tested in English laboratories. Babies from outside England but tested within an English laboratory will be included in the above. Portsmouth data includes babies from the Channel Islands and babies born to military families.

†‘Asian’ includes ‘Indian’, ‘Pakistani’, ‘Bangladeshi’ and ‘Any other Asian background’. ‘Other’ includes ‘Chinese’ and ‘Any other ethnic category’.

Figures are rounded and therefore do not appear to equal 100%.

Figure 9: Breakdown of babies that screened positive for a significant condition by ethnic category, screening year 2019 to 2020, English laboratories

Ethnic category	% of babies screen positive for a significant condition
Black African	63.7
Mixed	6.5
Asian†	6.9
White	0.4
Black Caribbean	11.4
Any other Black background	7.3
Not stated / not known	1.6
Other†	2.0

Data in Figure 9 includes all babies tested in English laboratories. Babies from outside England but tested within an English laboratory will be included in the above. Portsmouth data includes babies from the Channel Islands and babies born to military families.

†‘Asian’ includes ‘Indian’, ‘Pakistani’, ‘Bangladeshi’ and ‘Any other Asian background’. ‘Other’ includes ‘Chinese’ and ‘Any other ethnic category’.

Figures are rounded and therefore do not appear to equal 100%.

Figure 10: Breakdown of babies that screened positive for a carrier condition by ethnic category, screening year 2019 to 2020, English laboratories

Ethnic category	% of babies screen positive for a carrier condition
Black African	37.1
Mixed	19.6
Asian†	14.2
White	9.4
Black Caribbean	8.9
Any other Black background	5.0
Not stated / not known	2.9
Other†	2.9

Data in Figure 10 includes all babies tested in English laboratories. Babies from outside England but tested within an English laboratory will be included in the above. Portsmouth data includes babies from the Channel Islands and babies born to military families.

†‘Asian’ includes ‘Indian’, ‘Pakistani’, ‘Bangladeshi’ and ‘Any other Asian background’. ‘Other’ includes ‘Chinese’ and ‘Any other ethnic category’.

Figures are rounded and therefore do not appear to equal 100%.

4.3 Declined screening test

There is a year on year increase in the rate of declines newborn screening tests since screening year 2008 to 2009, with the largest increase seen between screening years 2017 to 2018 and 2018 to 2019 (Figure 11).

The increase in declines was investigated in screening year 2018 to 2019 with screening laboratories with the largest increase in declines and explained in the 2018 to 2019 SCT data report. Following on from this, further joint work with the NBS programme has now begun to investigate why there has been an increase in declines for SCD screening.

Figure 11: Declined screening tests for sickle cell disease, England, screening year 2005 to 2006 to screening year 2019 to 2020

Bristol laboratory data for first half of 2005 to 2006 is not included and Oxford and Portsmouth laboratories data is not included for whole of 2005 to 2006; Oxford laboratory data starts from 1st July 2006. Sheffield data is excluded for 2018 to 2019 and 2019 to 2020.

Figure 12 shows the trends in rates of declined screening tests be ethnicity, for babies where ethnicity is reported. The rate of declines increased in all ethnic categories apart from ‘Black Caribbean’ in screening year 2019 to 2020. The ‘Black Caribbean’ ethnic category was more similar to the other ethnic categories in screening year 2019 to 2020 following an increase in screening year 2018 to 2019. The rate of declines for the ‘Other’ ethnic category continued to increase in screening year 2019 to 2020.

Although not shown in figure 12, the rates of declined screening tests for babies where ethnicity was not stated or not known has increased from approximately 0.9 per 1,000 babies offered screening in screening year 2005 to 2006, to 112 per 1,000 babies offered screening in screening year 2019 to 2020.

Figure 12: Declined screening tests for sickle cell disease by ethnic category, England, screening year 2005 to 2006 to screening year 2019 to 2020

The above includes all babies tested in English laboratories. Therefore, babies from outside England but tested within an English laboratory will be include in the above. ‘Other’ includes the ‘Chinese’ and ‘Any other ethnic category’ ethnic groups. Babies with not stated or not known ethnic category have not been included in the above.

Bristol laboratory data for first half of 2005 to 2006 is not included and Oxford and Portsmouth laboratories data is not included for whole of 2005 to 2006; Oxford laboratory data starts from 1 July 2006. Bristol data is excluded for screening year 2018 to 2019. Sheffield data is excluded for screening years 2018 to 2019 and 2019 to 2020. Portsmouth data includes babies from military families and the Channel Islands in screening year 2019 to 2020.

4.4 Post-transfusion testing

Haemoglobin analysis is not suitable for testing samples from transfused babies as transfused red cells can survive up to 120 days in circulation. It is therefore important that pre-transfusion samples are taken in line with newborn blood spot sampling guidelines. The NBS programme introduced a pre-transfusion sample policy in 2008, as detailed in the guidelines for newborn blood spot sampling, which requires that blood spots should be taken for SCD screening before blood transfusion.

Figure 13 demonstrates that the incidence of post-transfusion samples has decreased since this policy was introduced, and the rates in England have remained stable over the last 4 years.

Table 15: Number and rates of post-transfusion samples reported by newborn screening laboratories, England, screening year 2017 to 2018 to screening year 2019 to 2020

Screening year 2017 to 2018

Region	n	Total tested	Rate / 1,000
London	190	129,967	1.46
Midlands and East	267	191,340	1.40
North	304	169,140	1.80
South	94	146,255	0.64
Unknown region	96	14,084	6.82
England total	951	650,786	1.46

Screening year 2018 to 2019

Region	n	Total tested	Rate / 1,000
London	165	123,121	1.34
Midlands and East	230	185,215	1.24
North	286	165,264	1.73
South	127	142,859	0.89
Unknown region	71	10,196	6.96
England total	879	626,655	1.40

Screening year 2019 to 2020

Region	n	Total tested	Rate / 1,000
London	187	122,270	1.53
Midlands and East	227	179,148	1.27
North	249	166,873	1.52
South	118	142,913	0.83
Unknown region	62	8,551	7.25
England total	843	616,755	1.37

Figure 13: Rates of post-transfusion samples, England, screening year 2005 to 2006 to screening year 2019 to 2020

Bristol data for first half of screening year 2005 to 2006 is not included and Oxford and Portsmouth data is not included for whole of screening year 2005 to 2006; Oxford data starts from 1st July 2006; Data from Manchester laboratory for screening year 2009 to 2010, from GOSH for screening year 2013 to 2014 and from Liverpool for screening year 2016 to 2017 are not available. Data for South East Thames in screening year 2013 to 2014 is excluded. Data for Portsmouth in screening year 2019 to 2020 includes babies from the Channel Islands and babies born to military families.

According to the guidelines for newborn blood spot sampling, where it is not possible to take a pre-transfusion sample, DNA testing is required to mitigate the risk of a missed baby.

DNA testing is provided by laboratories at King’s College Hospital and Sheffield Children’s Hospital, and the figures from these laboratories are shown in Tables 16 and 17.

Table 16: Numbers detected through DNA testing, reported by newborn DNA testing laboratories, England, screening year 2014 to 2015 to screening year 2019 to 2020

DNA testing	2014 to 2015	2015 to 2016	2016 to 2017	2017 to 2018	2018 to 2019	2019 to 2020
Total specimens received per year	1,123	1,198	1,071	1,012	1,004	1,056
Number of negative results (HbS not detected)	1,106	1,183	1,054	992	979	1,036
Number of heterozygotes	16	15	17	19	21	20
Number of homozygotes	1	0	0	0	2	0

Table 17: Number of samples for DNA testing received from each screening laboratory, England, screening year 2019 to 2020

Newborn DNA testing laboratory	Newborn screening laboratory	Number of samples
King’s College Hospital	Bristol	41
King’s College Hospital	Cambridge	36
King’s College Hospital	Great Ormond Street	171
King’s College Hospital	Oxford	22
King’s College Hospital	Portsmouth	46
King’s College Hospital	South East Thames	210
King’s College Hospital	South West Thames	39
Sheffield	Leeds	71
Sheffield	Liverpool	64
Sheffield	Manchester	59
Sheffield	Newcastle	59
Sheffield	Sheffield	143
Sheffield	West Midlands	95
	England total	1,056

5. SCT antenatal data return form

5.1 Antenatal data return from part 2: breakdown of screen positive women

A matrix grid is used to determine pregnancies at risk of a clinically significant condition. The mother’s antenatal results are matched to the father’s antenatal result and inputted into the grid. Pregnancies that are at risk of a clinically significant haemoglobin condition are those that are identified as having a 1 in 4 change or higher of the fetus having a clinically significant haemoglobin condition.

The matrix was changed in screening year 2018 to 2019 to include orange boxes (for pregnancies at risk of a clinically significant condition – PND should be offered) or white boxes (minimal risk of a clinically significant condition). The blue indicate that the biological father is not a carrier. The yellow boxes indicate that the biological father was unavailable for testing or declined testing. The current return form is available to download.