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Annex 5.9.1

PICO 7 - Dried blood spots

Dried blood spots as a sample collection method for

hepatitis B surface antigen serological testing

A systematic review and meta-analysis

MSF Access Campaign

Chauffour J, Gummadi N, Nagarantham A, Roberts T, Cohn J (Team lead)

Médecins Sans Frontières, Geneva, Switzerland

August 2015

Page | 449

1. Abstract Introduction: Several expert organizations recommend screening of individuals living in high or

even intermediate prevalence of hepatitis B. Despite this, few countries have or implement such

screening recommendations. In high-prevalence low- and middle-income countries, there is a

need for improved HBV screening, especially in decentralized settings. The use of dried blood

spots (DBS) sent to centralized lab facilities may be useful in certain contexts. A systematic review

and meta-analysis were performed to address the question: Among persons identified for

hepatitis B testing, what is the diagnostic accuracy and impact of detecting HBsAg from DBS

samples versus venous sample?

Methods: Following an a priori protocol, PubMed, MEDLINE, WHO Global Index Medicus, Web of

Science, MSF, Cochrane, EMBASE, CABS Abstracts and LILACS databases were searched by two

reviewers in duplicate. Data were extracted with the primary outcome of HBsAg DBS test accuracy

using the gold standard of a venous sample. For analysis of sensitivity and specificity, a bivariate

analysis using a maximum likelihood estimate and 95% confidence intervals was used. Likelihood

ratios were calculated directly from the pooled sensitivity and specificity. QUADAS-2 was used to

assess bias and a GRADE evaluation was performed to evaluate the quality of included studies.

Results: Two hundred forty studies were obtained for consideration, of which 10 met the criteria

for inclusion in the review and 9 provided sufficient data for inclusion in the meta-analysis. The

meta-analysis revealed a sensitivity of 92.9% (upper bound–lower bound 86.2–96.5) and

specificity of 99.0% (upper bound–lower bound 96.2–99.7). From the pooled sensitivity and

specificity, the positive likelihood ratio is 92.9 and the negative likelihood ratio is 0.072. As

heterogeneity was identified on the forest plots, stratified analyses were done by storage

temperature and test cut-off values. The analysis stratified by storage temperature revealed a

sensitivity of 78.7% (upper bound–lower bound 70.3–85.2) and 96.1% (upper bound–lower bound

91.9–98.2) for cold chain versus ambient temperature or higher, and a specificity of 98.6% (upper

bound–lower bound 68.0–100) and 99.7% (upper bound–lower bound 98.3–100) for cold chain

versus ambient temperature or higher. The analysis stratified by test cut-off revealed a sensitivity

of 88.0% (upper bound–lower bound 74.0–95.0) and 95.6% (upper bound–lower bound 91.2–

97.8) for standard and lowered cut-off, respectively, and a specificity of 98.6% (upper bound–

lower bound 89.5–99.8) and 99.1% (upper bound–lower bound 96.6–99.8), respectively. The

assessment for risk of bias revealed some risk due to patient selection and interpretation of index

test. The GRADE analysis showed the included studies to provide evidence of moderate quality to

assess sensitivity and specificity.

Discussion: This review includes evidence of moderate quality that supports acceptable accuracy

of DBS for testing HBSAg as compared to use of plasma samples and suggests that DBS may be

used where there is limited access to venepuncture or inadequate technology to prepare and

transport plasma samples. It is important to note that use of DBS may require changing cut-offs to

Page | 450

determine test positivity. As there are relatively little data on accuracy of DBS in real-life

conditions (including high humidity), operational research will be needed in real-life conditions.

2. Introduction According to the World Health Organization’s latest data, an estimated 240 million people are

chronically infected with the hepatitis B virus (HBV) and more than 780 000 people die every year

due to complications of hepatitis B.1 In 20–30% of chronically infected individuals, hepatitis B

progresses to liver cancer and/or cirrhosis.2 For some individuals, acute hepatitis shortly after

infection can cause fatal liver failure. Hepatitis B disproportionately affects populations in low-

and middle-income countries: adult chronic infection prevalence in sub-Saharan Africa and East

Asia is 5–10% (similar high rates affect populations in the Amazon and south-east and south-

central Europe), and of 2–5% in the Middle East and India.3

Several organizations such as the US Centers for Disease Control and Prevention (CDC),

the European Association for the Study of the Liver (EASL) and the American Association for the

Study of Liver Diseases (AASLD) recommend screening of individuals living in high or even

intermediate prevalence. Despite this, few countries have or implement such screening

recommendations and a very large number of individuals living with HBV are not diagnosed. In

high-prevalence low- and middle-income countries, there is a need for improved HBV screening,

especially in decentralized settings. While commercial rapid tests exist, the use of dried blood

spots (DBS) sent to centralized lab facilities may be useful in certain contexts.

There are a number of HBsAg serological tests used, including rapid diagnostic tests

(RDTs) and enzyme immunoassays (EIAs). Among RDTs, there are numerous options, such as the

Determine HBsAg RDT. A recent meta-analysis of accuracy of hepatitis B RDTs demonstrated that

the pooled sensitivity was 94.76% (95% credible interval [CrI] 90.08–98.23%) and specificity was

99.54% (95% CrI 99.03–99.95%).4

Use of DBS

Hepatitis B surface antigen (HBsAg) is the screening test for HBV. Use of DBS for HBV screening

may simplify sample collection and preparation (e.g. through collection of finger-prick blood

samples) and improve the ability to store and transport samples for testing.5,6 Starting with the

sample collection method, blood can easily be collected from pricking a finger or a heel, thus

reducing the need for more highly-trained health-care workers. For DBS, less blood volume is

required than in conventional venepuncture, and sample preparation is simple (it does not

require electrical power, or a centrifuge), and inexpensive. Furthermore, once collected, the

handling of the samples is rendered more easy: samples are less cumbersome, and can be

transported in little space and at room temperature thus reducing or eliminating need for cold

chain. Finally, individuals conducting the tests on the samples have a reduced risk of

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contamination once the blood has dried. This technique has already had success in diagnosing

other infections such as HIV and is being developed for screening of other diseases such as

hepatitis C.7 It has also been used since decades for the mass screening of congenital disorders

and neonatal diseases, such as hypothyroidism and phenylketonuria (Guthrie test).

In March 2015, WHO published the first guidelines for the prevention, care, and

treatment of individuals with chronic HBV infection. These guidelines focused on assessment for

treatment eligibility, initiation of first-line therapies, switching, and monitoring, and did not

include screening recommendations. WHO is now undertaking guidelines for testing for chronic

hepatitis B and C infection in low- and middle-income settings. A topic for consideration in these

guidelines is the potential use of DBS for serological and molecular testing for HBV and HCV to

facilitate access to and uptake of testing.

In order to better evaluate the sensitivity and specificity of DBS for testing for HBsAg, the

following PICOT question was developed for HBsAg. Among persons identified for hepatitis B

testing, what is the diagnostic accuracy and impact of detecting HBsAg from DBS samples versus

venous sample?

Population: Samples for serology (HBsAg) for HBV

Intervention: Using DBS samples

Comparisons: Using plasma or serum from venous samples

Outcomes: Diagnostic accuracy (Sensitivity, Specificity, Positive likelihood ratio, Negative

likelihood ratio, TN, TP, FN, and FP)

3. Methods A protocol was prepared for the literature search, article selection, data extraction and

assessment of methodological quality.

a. Search strategy and selection criteria

Types of studies

Case–control, cohort, and cross-sectional and randomized trials were included and articles were

selected that compared DBS HBsAg testing against the gold standard of HBsAg testing using

serum, and reported specificity and sensitivity or sufficient data to calculate sensitivity and

specificity.

Participants

No date, geographical or population demographic exclusions were used. Patients of all age groups

were included.

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Target conditions

For use in screening for or diagnosing hepatitis B

Reference standard

Testing for HBsAg in serum using any commercially available test

Outcome measures

Sensitivity refers to the proportion of samples with true HBV infection diagnosed with a positive

HBsAg test using DBS confirmed with a positive HBsAg in serum.

Specificity refers to the proportion of samples with negative HBsAg using DBS and no evidence of

HBV infection confirmed with a negative HBsAg in serum.

Search methods

We searched English language manuscripts from PubMed, MEDLINE, WHO Global Index Medicus,

Web of Science, MSF, Cochrane, EMBASE, CABS Abstracts and LILACS databases using the search

terms contained in Annex 1. The search was conducted between April and June 2015.

Title, abstract and full-text review was done in duplicate using pre-defined eligibility

criteria with a third reviewer serving as a tie-breaker for inclusion disagreements. The reference

lists for articles selected for inclusion were also reviewed for additional manuscripts to review.

Additional data and clarifications were sought by contacting study authors. Two articles were

excluded because of inability to locate the full text of these articles.

b. Data extraction

All the studies were subject to the same data extraction procedure and form based on the

following parameters: author, publication and study dates, country and their World Bank

economic category (high, middle/low income, or both high and middle/low income), percentage

of HIV-positive participants, percentage of children and adults, age range, gender distribution,

study design, participant selection, direction of study (prospective vs retrospective), type of

specimen used for DBS, specimen used as gold standard (plasma or serum), test used, and

whether or not the tests were administered following the recommendations from the

manufacturer. Two reviewers independently extracted data. Studies without extractable

sensitivity or specificity data were excluded from the meta-analysis.

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c. Statistical data analysis

Statistical analysis of the data was performed using OpenMeta [Analyst]. For analysis of sensitivity

and specificity, a bivariate analysis using maximum likelihood estimate and 95% confidence

intervals was used. Likelihood ratios were calculated directly from the pooled sensitivity and

specificity. We used forest plots to visually assess heterogeneity. Stratified analysis was

performed by studies that used the standard manufacturer-recommended cut-off value and those

that used a lower cut-off, and by studies that stored DBS in the cold chain (refrigerated or frozen)

and those that stored the DBS samples at ambient temperatures or higher.

d. Risk of bias and quality assessment

The QUADAS-2 tool was used to assess risk of bias. A GRADE assessment performed by two

reviewers in parallel to assess the quality of included studies.

4. Results

a. Summary of included studies

A search yielded 240 studies for consideration of which 108–17 met the criteria for inclusion in the

review (Fig. 1 and Table 1) and 9 provided sufficient data for inclusion in the meta-analysis.8–11, 13,

14, 16, 17 The studies provided 370 positive samples among 1516 total samples. Four studies were

from high-income countries,10, 14–16 four from middle-income countries8, 9, 12,17 and two from low-

income countries.11, 13 Five studies drew samples from broad populations, including pregnant

women,8, 9, 13–15 two from inpatient populations,10, 12 two from attendees at liver clinics16, 17 and

one from attendees of an HIV testing centre.11 Storage conditions including time and temperature

varied among the studies, with 3 studies keeping samples in refrigerated or frozen storage,8, 9, 12

six studies with some or all samples at ambient temperature or higher10, 11, 13, 14, 16, 17 and one not

specified.15 Finally, some studies lowered the test cut-off value for DBS samples while others used

the manufacturer-recommended cut-off level.

b. Diagnostic performance

In general, testing for HBsAg using DBS maintained good accuracy as compared with the reference

test using plasma or serum. The meta-analysis revealed a sensitivity of 92.9% (upper bound–lower

bound 86.2–96.5) and specificity of 99.0% (upper bound–lower bound 96.2–99.7) (Table 4 and

Page | 454

Figs 2 and 3). From the pooled sensitivity and specificity, the positive likelihood ratio is 92.9 and

the negative likelihood ratio is 0.072.

c. Impact of storage conditions

A range of storage conditions were evaluated in the included papers, including storage

temperature ranging from –20 to 33°C and storage time ranging from overnight to 180 days. In

general, storage at room temperature or higher (30–33°C) did not affect accuracy of testing as

compared to storage in the cold chain. However, the two studies that evaluated storage at room

temperature or higher with prolonged storage time did note a decrease in sensitivity when

samples were stored for >15 days at room temperature16 or a decrease in sensitivity and

specificity for samples stored at room temperature for more than 63 days.17 A stratified analysis

of studies that stored samples in the cold chain (refrigerated at 2–8°C or frozen)8, 9 versus those

that stored samples at ambient temperature or above (30–33°C)11, 13, 14 was performed for 5

studies (2 cold chain and 3 ambient temperature or higher). Other studies were excluded as they

examined DBS samples in a range of temperature conditions, but did not provide sufficient

information to determine sensitivity or specificity at a given temperature. The analysis revealed a

sensitivity of 78.7% (upper bound–lower bound 70.3–85.2) and 96.1% (upper bound–lower bound

91.9–98.2) for cold chain versus ambient temperature or higher and a specificity of 98.6% (upper

bound–lower bound 68.0–100) and 99.7% (upper bound–lower bound 98.3–100) for cold chain

versus ambient temperature or higher (Figs 4 and 5).

d. Impact of cut-off

Several papers noted that the ideal cut-off (e.g. as suggested by receiver operating characteristic

[ROC] curves) for determining test positivity should be lower for DBS samples as compared to

plasma or serum samples (Table 1).11–12, 15 Authors postulated this was due to the small blood

volume used in DBS (commonly 50 µL for a circle of 12 mm diameter). Stratified analysis by cut-off

value (standard versus raised) revealed a sensitivity of 88.0% (upper bound–lower bound 74.0–

95.0) and 95.6% (upper bound–lower bound 91.2–97.8) for standard8, 9, 13, 16 and lower cut-off,10,

11, 14, 17 respectively, and a specificity of 98.6% (upper bound–lower bound 89.5–99.8) and 99.1%

(upper bound–lower bound 96.6–99.8), respectively (Figs 6 and 7).

e. Assessment of bias and quality assessment

The assessment for risk of bias revealed that several studies did not use a random or consecutive

sampling method or used a study population that is not consistent with the target screening

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population.8, 13, 14, 16, 17 As there are no current standards for test cut-offs for HBsAg using DBS,

several studies used results of ROC curves to change the cut-off used for the DBS samples,

adjusting the cut-off downward to achieve better sensitivity.10–12, 14, 15, 17 This adjustment may

introduce bias and thus, these studies were judged to have a high risk of bias on the index test

domain. The included studies had a low risk of bias on the reference test and flow and timing

domains (Table 2). The GRADE analysis showed the included studies to provide evidence of

moderate quality to assess sensitivity and specificity (Table 3).

5. Discussion Overall conclusions

This systematic review and meta-analysis includes evidence of moderate quality that supports

acceptable accuracy of DBS for testing HBsAg as compared to use of plasma samples, and

suggests that DBS may be used for screening for HBV using HBsAg DBS where there is limited

access to venepuncture or inadequate technology to prepare and transport plasma samples.

Although studies are limited, DBS is likely stable and maintains good accuracy in conditions with

higher temperatures and with higher humidity, although accuracy may be negatively affected

when storing for prolonged durations (>14 days) at higher temperatures (room temperature and

above). In a stratified analysis that examined studies that stored samples in a cold chain versus

those that stored samples at ambient or higher temperatures did not reveal a detriment in

accuracy for DBS stored at ambient or higher temperatures. As there are relatively little data on

accuracy of DBS in real-life conditions (including high humidity), operational research will be

needed in real-life conditions.

It is important to note that use of DBS may require changing cut-offs to determine test

positivity. As DBS uses a small sample of blood, in order to maintain sensitivity, a lower cut-off

may be required as compared to when using plasma samples. In the stratified analysis performed

examining standard or lower cut-off values, DBS that used a lower-cut off had a higher sensitivity

than those that used the manufacturer-recommended cut-off without sacrificing significant

specificity. Each individual test kit needs to be evaluated separately for its own ideal cut-off for

DBS based on a ROC curve. This will usually differ from the serum test cut-off and usually be a

lower cut-off to increase sensitivity. It will be important to validate use of DBS with commercially

available HBsAg tests and determine cut-off values.

Key limitations

This review also has a number of limitations. Overall, the number of studies was small. In

particular, there is a dearth of studies that systematically examine the effects of storage

conditions on the accuracy of DBS and of those that did assess this, several did not specify the

exact conditions (e.g. exactly what is room temperature). Thus, should DBS be adopted for

screening for HBV, it will be important to pursue further operational research using field

specimens in prepared and stored in real-life conditions. Ideally, to fit operational needs, these

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studies should use capillary whole blood to prepare the DBS, use a commonly available type of

filter paper while comparing several commercial test kits and conditions of storage.

Future work

Expanded use of HBsAg testing will be critical to improving the diagnosis and treatment of HBV

globally. While commercial HBsAg rapid diagnostic tests may be useful in certain contexts, the

ability to use DBS for improved preparation, storage and transport of samples for decentralized

testing may help to expand the reach of this important diagnostic test.

Fig. 1. Study flow diagram

Number of records in EndNote

database: 240

Excluded Screen 1: 194

Reason: Not relevant based on

abstract

Potential relevant titles 378

PubMed: 53

Embase: 91

Web of Science: 154 De-duplication

(total duplicates:

138)

Excluded Screen 2: 34

Reasons:

Did not evaluate accuracy of

DBS: 26

Did not include primary

outcome: 4

Not a study: 3

Studies included for

WHO analysis: 10

Full papers retrieved: 46

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Table 1. Study-level characteristics of included studies

Author Country and

income

category

Study design Study pop Sample size Storage conditions Reference test Sample for

DBS

Filter paper Specificity Sensitivity Cut-off value Effect of storage

conditions

Boa-Sorte

2014

Brazil

Upper–middle

income

Cross-

sectional

Pregnant

women

692 Temperature:

refrigerated

Time: less than 5

days

IMUNOSCREENHBSAG–SS

(Mbiolog Diag.) and Murex HBsAg

(MurexBioTechUnlmtd)

Venous Schleicher

and Schuell

903

100 100 Unchanged

Forbi

2010

Nigeria

Lower–middle

income

Cross-

sectional

Broad 300 Temperature: 4 °C

Time: overnight

Shantest TM- HBsAg ELISA Venous Whatman

no. 3

88.6 78.6 Unchanged

Gruner

2015

Germany

High income

Cross-

sectional

Inpatients 299 Temperature: 20 °C,

4 °C or ambient

temperature

Time: up to 14 days

HBsAg assay ARCHITECHT system

(Abbott Diagnostics)

Venous or

capillary

PerkinElmer

226 and

Whatman

no. 3

99.8 91.7 0.15 IU/mL

Kania

2013

Burkina-Faso

Low income

Cross-

sectional

Attendees of

HIV testing

centre

218 Temperature:

ambient

temperature

Time: not specified

ETI-MAK-4 HBsAg EIA (DiaSorin

S.p.A.)

Venous Whatman

903

100 96 Optical density:

MAPC (mean

absorbance of

positive

control)/2

+

0.3 standard

deviations=

0.825.

Lee

2011

Malaysia

Upper middle

income

Cross-

sectional

Patients at a

tertiary

hospital

150 Temperature: 20 °C

Time: not specified

Abbott, kit not specified

(Abbott Laboratories)

Venous Whatman

903

97.8 96.5 Cut-off point of

1.72

Relative light

units

Mendy

2005

The Gambia

Low income

Cohort Broad 166 Temperature: 30–

33 °C (humid

conditions)

Time: up to 4 weeks

Determine HBsAg (Abbott

Laboratories)

Venous Whatman,

grade BFC

180

100 96 Unchanged

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Mohamed

2013

France

High income

Cohort Broad 200 Temperature: Room

temperature

Time: 1, 3, 7 and 14

days

Abbott ARCHITECT HBsAg assay

(Abbott Laboratories)

Venous Whatman

FTA DMPK-

C

100 98 0.30 +/-0.81

IU/mL

No significant

change

Ross

2013

Germany

High income

Cross-

sectional

Broad 299 Time and

temperature not

specified

Abbott ARCHITECT HBsAg

(Abbott Laboratories)

Venous Not

specified

100 98.6 15 IU/mL (HBsAg)

Villa

1981

Italy

High income

Cross-

sectional

Patients

attending liver

clinic

24 Temperature: -20 °C,

4 °C and room

temperature.

Time: 1,7, 15, 30, 60,

and 180 days

Ausria II, RIA kit

(Abbott Laboratories)

Capillary Not

specified

100 100 Unchanged Temperature:

storage at room

temperature

resulted in no

significant change

compared to

samples stored at

4 °C or -20 °C

Time: storage longer

than 15 days

negatively affected

sensitivity.

Villar

2011

Brazil

Upper middle

income

Cross

sectional

Patients

attending

hepatitis clinic

133 Temperature:

–20 °C, 4–8 °C, 22–

25 °C

Time: 1, 7, 14, 21,

42, 63, 112,

and 183 days

ETI-MAK-4 HBsAg (Diasorin) Venous or

capillary

Whatman

903

96.7 97.62 Absorbance value

0.115

Accuracy of DBS

samples was stable

over 63 days

at all temperatures

evaluated but after

63 days, accuracy

diminished when

stored at 22–25 °C

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Table 2. QUADAS-2 risk of bias assessment

Author Patient selection Index test Reference standard Flow and timing

Boa-Sorte LR LR LR LR

Forbi LR LR LR LR

Gruner LR HR UR UR

Kania LR HR LR LR

Lee LR HR LR LR

Mendy HR LR LR LR

Mohamed HR HR LR LR

Ross LR HR LR LR

Villa HR LR LR LR

Villar HR HR LR LR

HR: high risk of bias; UR: unknown risk of bias; LR: low risk of bias

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Table 3. GRADE table

Number of studies Type of study Directness Precision Consistency Risk of bias Overall quality

Sensitivity 92.9% (95% CI 86.2–96.5)

10 studies

(370 HBsAg

positive among

1516 samples)

Cross-sectional

or cohort

No significant

indirectness

No significant

imprecision

Significant

inconsistency

(one paper reported

lower sensitivity)

Significant risk of bias (patient

enrolment not consecutive or random

in some studies; pre-specified cut-off

not used in some studies)

Moderate

Specificity 99.0% (95% CI 97.6–100%)

10 studies

(370 HBsAg

positive among

1516 samples)

Cross-

sectional or

cohort

No significant

indirectness

No significant

imprecision

No significant

inconsistency

Significant risk of bias (patient

enrolment not consecutive or random in

some studies; pre-specified cut-off not

used in some studies)

Moderate

Page | 461

Table 4. Meta-analysis: sensitivity and specificity

Estimate Upper bound–lower bound

Sensitivity 92.98 6.2–96.5

Specificity 99.09 6.2–99.7

Fig. 2. Forest plot sensitivity

Page | 462

Fig. 3. Forest plot specificity

Page | 463

Fig. 4. Forest plot, sensitivity at differing storage temperatures

Maintained in cold chain (refrigerated or frozen)

Maintained at room temperature or higher

Page | 464

Fig. 5. Forest plot, specificity at differing storage temperatures.

Maintained in cold chain (refrigerated or frozen)

Maintained at room temperature or higher

Page | 465

Fig. 6. Forest plot sensitivity, standard and lowered cut-off

Standard cut-off

Lowered cut-off

Page | 466

Fig. 7. Forest plot specificity, standard and lowered cut-off

Standard cut-off

Lowered cut-off

Page | 467

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Appendix 1: Search strategies

Pubmed

(("Hepatitis B" [Mesh] OR "Hepatitis B virus" [Mesh] OR “hepatitis B” OR “hepatitis B virus” OR

“HBV”) OR (“Hepatitis B Antigens” [Mesh] OR “Hepatitis B Surface Antigens” [MESH] OR

hepatitis b antigen* OR hepatitis b virus antigen* OR hepatitis b surface antigen* OR “HBsAg”

OR “hbv sag” OR "hb sag" OR "HBsAg") AND (“Dried Blood Spot Testing”[Mesh] OR “dried

blood spot testing” OR dried blood spot* OR dried plasma spot* OR “DBS” OR “dried blood”

OR “dried plasma”))

Embase

1. ‘hepatitis b’/exp OR ‘hepatitis b antigen’/exp OR ‘hepatitis b surface antigen’/exp OR

‘hepatitis b virus’/exp

2. ‘hepatitis b’ OR ‘hepatitis b virus’ OR ‘hepatitis b surface antigen’ OR ‘hepatitis b

antigen’ OR ‘hbv’ OR ‘HBsAg’ OR ‘hepatitis b sag’ OR ‘hbv sag’ OR ‘hbsag’ OR ‘hb sag’

3. ‘dried blood spot testing’/exp OR ‘dried blood spot testing’ OR ‘dried blood spot’ OR

‘dried blood’ OR ‘dried plasma spot testing’ OR ‘dried plasma spot’ OR ‘dried plasma’

OR ‘dbs’

4. #1 OR #2

5. #3 AND #4

Web of Knowledge (SCI-expanded, SSCI, Conference Proceedings science, BIOSIS previews)

1. TOPIC: (hepatitis b) OR TOPIC: (hepatitis b surface antigen) ORTOPIC: (hepatitis b

antigen) OR TOPIC: (hepatitis b virus) OR TOPIC: (hbv) OR TOPIC: (HBsAg) OR TOPIC:

(hbv sag) OR TOPIC: (hbsag) OR TOPIC: (hb sag)

Indexes = SCI-EXPANDED, SSCI, A&HCI Timespan=All years

2. ((((((TOPIC: (dried blood spot testing) ORTOPIC: (dried blood spot)) ORTOPIC: (dried

blood)) ORTOPIC: (dried plasma spot testing)) ORTOPIC: (dried plasma spot)) ORTOPIC:

(dried plasma)) ORTOPIC: (dbs))

Indexes = SCI-EXPANDED, SSCI, A&HCI Timespan=All years

3. #2 AND #1

Indexes= SCI-EXPANDED, SSCI, A&HCI Timespan=All years

Cochrane

1. MeSH descriptor: [Hepatitis B] explode all trees

2. MeSH descriptor: [Hepatitis B Antigens] explode all trees

3. MeSH descriptor: [Hepatitis B Surface Antigens] explode all trees

4. MeSH descriptor: [Hepatitis B virus] explode all trees

5. hbv or hepatitis b or hepatitis b virus or hepatitis b antigen or hepatitis b surface

antigen or HBsAg or hbv sag or hbsag or hb sag

6. MeSH descriptor: [Dried Blood Spot Testing] explode all trees

Page | 470

7. dried blood spot testing or dried blood spot or dried blood or dried plasma spot testing

or dried plasma spot or dried plasma or dbs

8. #1 or #2 or #3 or #4 or #5

9. #6 or #7

10. #8 and #9

Medline (OVID)

1. exp Hepatitis B/ or exp Hepatitis B virus/ or hepatitis B.mp. or hepatitis b virus.mp. or

hbv.mp.

2. exp Hepatitis B Antigens/ or exp Hepatitis B Surface Antigens/ or hepatitis b

antigen*.mp. or hepatitis b virus antigen*.mp. or hepatitis b surface antigen*.mp. or

hbsag.mp. or hbv sag.mp. or HBsAg.mp. or hb sag.mp.

3. exp Dried Blood Spot Testing/ or dried blood spot testing.mp. or dried blood

spot*.mp. or dried plasma spot*.mp. or dbs.mp. or dried blood.mp. or dried

plasma.mp.

4. 1 or 2

5. 3 and 4