Roanna George

Principal Clinical Scientist

Welsh Public Health Conference

November 2015

Wales Newborn Screening Laboratory, University Hospital of Wales

Effect of Sample Quality on Newborn

Screening Results and

Quality Improvement Implementation

Newborn bloodspot screening in

Wales Aims to prevent serious but rare conditions through early

treatment before symptoms develop

~36,500 babies screened per year

Testing for: Six inherited metabolic disorders:

Phenylketonuria (PKU)

Medium chain Acyl-CoA dehydrogenase deficiency (MCADD)

Maple Syrup Urine Disease (MSUD)

Isovaleric Acidaemia (IVA)

Glutaric Aciduria Type 1 (GA1)

Homocystinuria (HCU)

Congenital hypothyroidism (CHT)

Cystic fibrosis (CF)

Sickle cell disorders (SCD)

Newborn Bloodspot Screening

• UK newborn screening using bloodspot

samples

• Taken on day 5-8 (including premature or ill

babies)

Sample Quality Guidelines

Does Sample Quality Matter?

Bloodspot Quality Project

• Aim: • Determine whether bloodspot quality effects screening results

• Methods: • Create whole blood pools at screening cut-off concentrations

• Create cards of different sample quality to compare the results

• Different sample volumes

• Double layered spots

• Samples spotted on the front and back of the card

• Multi-spotted samples

• Insufficient samples

• Compressed samples

Central and Peripheral Punches

• Card prior to punching:

• Central and peripheral punches were

taken from each card:

Volume Experiments

Sample Volume

100 uL 75 uL 50uL 20uL 10uL

Effect of blood volume and punch location on amino acid

concentrations

-30

-25

-20

-15

-10

-5

0

5

10

15

20

10µL C 20µL C 75µL C 100µL C 20µL P 50µL P 75µL P 100µL P

Phe

(239µMol/L)

Tyr

(183µMol/L)

Met

(43µMol/L)

Leu

(594µMol/L)

n=30, error bars represent ±SD, * p<0.001, ‡ P<0.05

*

‡ *

*

*

*

*

*

* *

*

* *

*

*

*

% C

han

ge in

co

ncen

trati

on

fro

m a

50µ

L s

po

t

wit

h a

cen

tral p

un

ch

* *

*

* *

* * *

* * ‡ ‡

C = Central punch, P = Peripheral Punch

Poor Quality Experiments

Poor Quality Experiments

• Insufficient:

• Compressed:

(b) 50uL normal spots

(a) 20uL compressed spots

(a) (a)

(b) (b)

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

15

Insuff C Comp C 20µl P Insuff P Comp P

Effect of poor quality blood spots and punch location on amino acid

concentrations

Phe

(239µMol/L)

Tyr

(183µMol/L)

Met

(43µMol/L)

Leu

(594µMol/L)

n=30, error bars represent ±SD, * p<0.001, ‡ P<0.05

*

*

* * *

* *

*

* *

*

% C

han

ge in

co

ncen

trati

on

fro

m a

20µ

L s

po

t

wit

h a

cen

tral p

un

ch

*

‡

C = Central punch, P = Peripheral Punch, Insuff = insufficient, Comp = Compressed

UK National Guidelines

UK National Guidelines

• 4 filled circles

• Can accept over-spotted samples

• Risk of false positive but a case will not be missed

• Must reject:

• Insufficient and multi-spotted samples

• Heterogeneous results and risk of false negative

• Compressed and small volume samples:

• SIGNIFICANT RISK OF NEGATIVE BIAS

• A DISORDER MAY BE MISSED

Case Study

MCADD Case

• Below is a picture of the sample received into

the lab for a screen positive MCADD baby

• Spots are good quality:

MCADD Screening Protocol

Analytical cut-off

Clinical cut-off

MCADD case

• C8 = 0.55 umol/L (referral cut-off 0.5 umol/L)

Sample Quality % Bias C8 (umol/L)

10 uL -22% 0.43

20 uL -15% 0.47

Insufficient (best spot) -3% 0.53

Insufficient (worst spot) -10% 0.50

Compressed -31% 0.38

Result is below the analytical

AND clinical cut-off

Quality Improvement Strategy

Quality Improvement Strategy

• Set up Poor Quality 1 (PQ1) and Poor Quality 2 (PQ2) categories • PQ2 to act as a warning that sample quality is poor without rejecting

samples

• Monthly feedback to governance leads with sample taker names

• Laboratory introduced step-wise increase in sample rejection

• Training and education, resources include: • Talk on why bloodspot quality matters at midwife training days

• Interactive newborn screening card

• Bloodspot sampling video

• Midwife video

• Lancet audit • Cost of lancets vs cost of re-bleeding babies

Lancet Graph

Number of Punches vs Lancet Type - Proposed Rules

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

≤4 5 6 7 >7

Number of Punches Possible

Perc

en

tag

e

Tenderfoot

Greiner Bio1 vacuette mini collection 2x1.5mm

Acti-Lance 17G, 2.0mm

BD Microtainer® Contact-Activated High f low (2x1.5mm)

BD Microtainer® Contact-Activated Med flow 21G (1.8mm)

Ow en Mumford, Unistik 3 Neo & Lab, 18G, 1.8mm

BD Quikheel Infant 1x2.5mm

Ow en Mumford, Unistik 3 Extra, 21G, 2.0mm

Not stated

Quality Improvement Strategy

Outcome

Poor Quality Rejection Rate

0.00

5.00

10.00

15.00

20.00

25.00

Jun-14 Jul-14 Aug-14 Sep-14 Oct-14 Nov-14 Dec-14 Jan-15 Feb-15 Mar-15 Apr-15 May-15

Date

% R

eje

cti

on

Rate

Expected PQ rejection rate

Actual PQ Rejection Rate

PQ2 samples categorised against the new guidelines Guideline

Introduced (PQ2 category ceased)

Began step-wise increase in rejection rate in preparation for guideline implementation

Sample Quality

• Sample quality important to:

• Avoid false positives

• Avoid false negatives

• Prevent delay in referral if

repeat samples are required

• Prevent re-bleeding a baby

• Prevent wasting healthcare resources

Sample Quality Guidelines

Summary

• Small volume and compressed samples give significant risk of negative bias

• Improvement of sample quality achieved by stakeholder engagement and education and training

• Improvement in bloodspot quality has increased efficiency and prevented: • Wasting healthcare resources

• Harm and anxiety to the baby and parents

• Implementation of bloodspot quality guidelines imperative to ensure accurate screening results and correct outcomes