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Antenatal Hepatitis B screening - is there a need for a national policy?   Back Bookmark and Share
M Cafferkey
Routine antenatal testing for hepatitis B carriage with maternal consent was introduced at the Rotunda in January 1998. The uptake of testing has been excellent; 99.98% of women presenting for antenatal care accepted hepatitis B (HBV) screening in the 30-months from January 1998 through June 2000. The prevalence of HBV carriage was 0.35% (58 pregnancies of 16,222 tested) increasing from 0.25% in 1998 (16 of 6227) to 0.45% in the first six months of 2000 (16 of 3484). Fifty-five women had 58 pregnancies (three women had two pregnancies). Two of these were e-antigen positive. HBV carrier status was previously unknown in 48 (87%). Two additional women had acute HBV infection in pregnancy. Forty-five infants have been born to mothers included in this screening programme. Audit of infant outcome reveals excellent compliance with immunisation and follow-up: 29 (64%) have completed the 3 dose HBV vaccination schedule to date. Thirteen infants (31%) are still attending; three are lost to follow-up including one whose family has emigrated. Routine antenatal screening for hepatitis B carriage is cost-effective and should be considered a standard of care in maternity practice.
Author : Cafferkey Mary, Beckett M, Butler KM, Cafferkey MT, Cahill I, Dooley S, Hall WW, Healy CM, MacMathuna P, McKenna PF, McMorrow J, Philbin M

Abstract

Routine antenatal testing for hepatitis B carriage with maternal consent was introduced at the Rotunda in January 1998. The uptake of testing has been excellent; 99.98% of women presenting for antenatal care accepted hepatitis B (HBV) screening in the 30-months from January 1998 through June 2000. The prevalence of HBV carriage was 0.35% (58 pregnancies of 16,222 tested) increasing from 0.25% in 1998 (16 of 6227) to 0.45% in the first six months of 2000 (16 of 3484). Fifty-five women had 58 pregnancies (three women had two pregnancies). Two of these were e-antigen positive. HBV carrier status was previously unknown in 48 (87%). Two additional women had acute HBV infection in pregnancy. Forty-five infants have been born to mothers included in this screening programme. Audit of infant outcome reveals excellent compliance with immunisation and follow-up: 29 (64%) have completed the 3 dose HBV vaccination schedule to date. Thirteen infants (31%) are still attending; three are lost to follow-up including one whose family has emigrated. Routine antenatal screening for hepatitis B carriage is cost-effective and should be considered a standard of care in maternity practice.

Introduction

Hepatitis B virus infection (HBV) is a common cause of morbidity and mortality worldwide. Chronic HBV infection, with persistence of hepatitis B surface antigen (HBsAg) is associated with the development of chronic liver disease, including cirrhosis or primary hepatocellular carcinoma in later life. The age at which HBV is contacted is the major determinant of developing carrier status, with the risk of chronic infection inversely related to the age at which infection occurs. Thus between 70 and 90% of infants infected perinatally from a HBsAg and HBe antigen positive mother become chronic carriers compared with 5-10% of those infected in late childhood or adult life1.

Perinatal infection is usually the result of maternal-infant (vertical) transmission2,3. Active immunisation with hepatitis B vaccine commencing within 24 hours of birth effectively reduces the risk of vertical transmission4,5. In the case of an infant born to an e antigen positive mother, (highest risk of vertical transmission), specific HB immunoglobulin administered as soon as possible after birth will further reduce the risk to the infant6. In geographical areas with a low prevalence of HBV infection, the most effective preventative strategy is to screen all pregnant women for HB carriage and immunise infants born to carrier mothers. In the long term such a strategy is cost effective and leads to significant health gain7-10. The objective of the present work was to assess the value of universal antenatal screening for hepatitis B surface antigen carriage at a busy maternity hospital, with regard to prevalence, acceptability of testing, identification of new cases and audit of outcome in the newborn. This was performed by review of the findings in the first 30 months of the routine screening programme.

Methods

Routine universal hepatitis B screening with informed consent was introduced at the Rotunda in January, 1998. Testing is performed at the first antenatal visit on an opt-out basis. Women who present at or close to term, or in labour are tested urgently with consent. The booking or admission history includes a pre-test discussion of the implications of testing, with assessment for risk factors for acquisition of blood borne viruses (coming from a high prevalence area, illicit drug use, transfusion of blood/blood products, sexual contact with an infected partner, tattoos/body piercing).

Hepatitis B surface antigen testing is performed in house (HBsAg, Abbott Axysm), on routine booking blood specimens. All specimens found to be reactive on screening at the Rotunda are referred to the Virus Reference Laboratory for confirmation and testing for additional HBV markers. Specimens from women who present unbooked at term or in labour are referred to the Virus Reference Laboratory for urgent testing.

Women with confirmed HBV carriage who are not already attending a hepatologist, or who have acute HBV infection in pregnancy are referred for formal assessment. Immunoprophylaxis for each infant is based on the results of maternal serology in the case of women found to be carriers and infants of the women with acute HBV in pregnancy are given both active and passive immunisation. All infants are referred for follow up to the Paediatric Infectious Diseases service. Serology is scheduled at eight months of life to check for infection status and appropriate vaccine response.

From January 1st 1998 until June 30th 2000, 16,224 women antenatal patients were offered a HBsAg test. Data was prospectively gathered on maternal and infant characteristics including mode of acquisition, obstetric and perinatal details. Where necessary, this data was supplemented by retrospective chart review.

Results

Uptake of antenatal HBsAg screening and seroprevalence:

The uptake of antenatal screening was 99.9 %. Two women refused screening. A total of 58 specimens tested HBsAg positive and additional markers and/or subsequent testing confirmed carrier status in all cases. In addition two women had acute HBV infection during the pregnancy and are included in this report. The overall seroprevalence of HBsAg carriage was 0.35%. This increased from 0.25% in 1998 (16 of 6227) to 0.39% in 1999 (26 of 6511) and 0.45% in the first six months of 2000 (16 of 3484). Non-EU patients accounted for 5.8% of the antenatal population at the Rotunda in 1998, increasing to 7.5% in 1999 and 11.4% in the first six months of 2000. The prevalence of HBsAg carriage in the non-EU antenatal population was 4% in 1998, 5.3% in 1999 and 4.4% in the first 6 months of 2000. The prevalence of HBsAg carriage in the Irishborn antenatal population throughout this time was 0.03% (see Table).

Maternal details

The total of 60 pregnancies in 57 women is included. This comprised 55 women who were HBsAg carriers and had 58 pregnancies (three women had two pregnancies) and two who had acute HBV in pregnancy. In 48 of the women (87%) this was a new diagnosis. Although seven of the HBsAg carrier mothers (13%) were aware of their status at booking, no woman had received treatment for hepatitis B and only one had undergone assessment of her liver status. Most were ill-informed about modes of HBV transmission and/or the availability of protective vaccines.

In all, 52 of the 57 women (91%) were non-EU and immigrants from areas of moderate or high HBV prevalence. Five women (9% of the total) were Irish nationals, including four HBsAg carriers and one woman who was diagnosed with acute HBV in the pregnancy. One of the latter gave a history at booking of intravenous drug use, and her HBV status would have been detected on selective screening, however, the remaining four had not been recognised as falling into a high risk group for hepatitis B infection. Following on detection of their status, careful questioning elicited that one woman had a history of body piercing and another had had a blood transfusion in the past; however, there was no evidence linking either event with the infection. In one woman, there was no identifiable risk factor. In the case of the final woman in this group who had acute HBV in pregnancy, it was subsequently found that her partner was a carrier (see Table 1).

Three women have transferred for antenatal care to another hospital, 43 have delivered and the remainder (11) are still attending for antenatal care.

Table 1 Findings, Maternal Demographics and Risk Factors for HBV infection
Characteristic
Number (%)
Total number offered test
16224
Total Number Screened
16222
1998
6227 (Non-EU 5.8%)
1999
6511 (Non-EU 7.5%)
2000
(6mo) 3484 (Non-EU 11.4%)
HBsAg +
58 pregnancies (0.35%) in 55 patients
HBsAg + status previously unknown 48/55 (87%)
HBsAg Prevalence
1998
16 of 6227 (0.25%)
1999
26 of 6511 (0.39%)
2000
(6mo) 16 of 3484 (0.45%)
Acute HBV in this pregnancy & HBsAg negative at booking
2
Country of origin of 55 HBV carriers (58 pregnancies) and 2 acute HBV infection
Non-EU
52 (91%)
Irishborn
5 ( 9%)
Risk factor:
IVDU
1
Presumed sexual
1
No risk identified
3

Infant outcome

Forty five infants (24 female, 21 male) have attended paediatric services. The median gestation was 40 weeks (range 34-42) and birthweight 3.28kg (range 1.81-4.26). Three (7%) were small for gestational age. Thirty six were vaginal deliveries (three forceps, one vacuum) and nine were born by caesarean section (three elective, six emergency). No significant neonatal adverse events were noted. Twenty infants (44%) received HBIG (e antigen positive or full markers not available). Forty four received their first dose of hepatitis B vaccine within 24 hours of birth (most in the delivery suite); one infant, whose maternal serology was performed 24 hours after birth, received both vaccine and HBIG within 48 hours. Three did not complete their schedule of vaccinations. In the case of one, whose family is known to have moved to the United Kingdom, the records have been forwarded to the appropriate health authority; two are lost to follow up and assumed to have left the jurisdiction. No infant to date is HBV infected; 15 who have had titres checked have mounted appropriate antibody responses (>10U/l).

Discussion

This pilot study demonstrated the acceptability and value of routine antenatal screening for hepatitis B carriage at a busy Dublin maternity hospital which serves the indigenous population and an increasing immigrant population. The prevalence of HBV carriage in the two years and six months studied was 0.35%. Only one woman had been referred for formal assessment by a hepatologist, and the majority were previously unaware of their hepatitis B carrier status. Most were ill-informed about modes of transmission of HBV and/or the availability of protective vaccines.

The World Health Organisation (WHO) recommends universal neonatal hepatitis B vaccination in countries of high endemicity (evidence of previous infection in more than eight percent of the young adult population). Data on the seroprevalence of acute HBV infection has been lacking in Ireland. This study gives data on the prevalence of HBV carriage at a busy Dublin maternity hospital and confirms the low HBV endemicity status. A recent community study has also confirmed this status11. Universal HBV vaccination is not at present offered in Ireland. Other measures are therefore needed to successfully prevent mortality and morbidity from HBV. Antenatal screening seems a logical step, given the frequency of maternal-infant transmission, the high rate of progression of infected neonates to carrier status and chronic infection, and the availability of a proven effective intervention to prevent such transmission.

Booking bloods are collected routinely on antenatal patients and serological tests performed, with maternal consent, for rubella, syphilis and HIV antibody. Inclusion of a hepatitis B screen to the routine antenatal tests will not usually require that additional specimens be taken at that time. Based on current costs, the maximum cost (reagent, consumables and analyser cost) per test is in the region of 3. Depending on the organisation within the individual laboratory, there may also be staff implications. Based on the maximum figure of 3 per test, the cost of the screening described in this report (16,222 tests) equates at 1,013 per new diagnosis. This is a highly cost-effective6-8 in light of the morbidity and mortality associated with vertically transmitted hepatitis B. The risk of vertical transmission from a carrier mother averages 25% (ranging from a risk of 82% is the mother is e-antigen positive, to 10% is she is e-antigen negative). Immunoprophylaxis by administration of a course of hepatitis B vaccine commencing as soon as possible after birth and in some cases (e-antigen positive mother, or mother who had acute HBV infection in this pregnancy) administration of specific hepatitis B immunoglobulin also, will lead to a 90% reduction in the risk of vertical transmission. Failure to detect the 48 previously undiagnosed carrier mothers in this study is likely to have resulted in at least 12 infected infants. It has been estimated that development of the carrier state following vertical transmission increases the risk of chronic liver disease some 20 times, and the risk of hepatoma some 86 times8 and both of these outcomes lead to significant morbidity with associated health-care costs, and mortality. In addition, vaccinating the infants of carrier mothers may also prevent horizontal transmission of hepatitis B in early childhood and it is estimated that this measure will prevent development of the carrier state in three extra children for each child protected from vertical transmission8.

It has been argued that a selective policy of antenatal screening for HBV will adequately detect carrier mothers and infants at risk of infection. Such a policy, as with HIV screening, relies heavily on administrator bias and a complete knowledge of what constitutes significant risk for infection. This study confirms that selective screening would miss a significant number of those infected. While most women detected under the screening programme were from areas of high prevalence, four of the HBsAg carriers detected (7%) and one woman who had acute HBV in pregnancy were Irish. Only one of these four carriers had a proven risk factor (intravenous drug use) and the sexual partner of the Irishwoman with acute HBV was found to be a carrier. It is also probable that seroprevalence in the indigenous population will rise further, with increasing travel to highly endemic areas and an evolving multi-cultural society. For these reasons we believe that a policy of routine screening with consent (opt-out) is more appropriate than a selective screening policy. Such a policy has the added advantages of being equitable and easier to implement.

The acceptability and adherence to treatment protocols for infants was very high. Only two infants are lost to follow up. The remainder all attended appropriately with no infant infections detected thus far. This programme also affords the opportunity to refer mothers to appropriate and necessary adult hepatology services. While this referral places demands on resources, it facilitates the initiation of treatment when required, and prevention of complications over time. It also facilitates testing and vaccination of susceptible contacts thereby reducing the risk of further spread.

Routine universal antenatal screening for hepatitis B has proven successful and cost effective at the Rotunda. This measure has allowed the detection of 55 women with chronic HBV carrier status of whom only 7 (12%) had been diagnosed previously and only one had been adequately assessed or treated. Audit of the outcome of this screening programme to date indicates that it has allowed successful immunoprophylaxis and prevented neonatal infection in all infants who have received a full course of active immunisation. These outcomes point to the need to adopt such a routine screening policy nationally.

Correspondence

Mary Cafferkey,
Consultant Microbiologist,
Rotunda Hospital,
Dublin 1.
Tel: +353 (01) 873 0700.
Fax: +353 (01) 872 0919.

References

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  2. Public Health Laboratory Service Hepatitis B. In: Sutherland S., ed., Torch Screening Reassessed: The Laboratory Investigation of Congenital, Perinatal and Neonatal Infection. The Report of a PHLS Working Party on Diagnostic tests for Congenital Infections. PHLS Colindale, 1993. 44-46
  3. Mieli-Vergani G. Hepatitis B virus. In: Greenough A., Osborne J., Sutherland S. eds., Congenital, Perinatal and Neonatal Infections, Churchill Livingstone, Edinburgh, 1992, 85-94
  4. American Academy of Pediatrics. Hepatitis B. In: Peter G, ed.1997 Red Book: Report of the Committee on Infectious Diseases. 24th ed. Elk Grove Village, IL: American Academy of Pediatrics; 1997: 247-260
  5. Vranckx R, Alisjahbana A, Meheus A. Hepatitis B virus vaccination and antenatal transmission of HBV markers to neonates. J Viral Hepat, 1999, 6 135-9
  6. Sangfelt P, Reichard O, Lidman K, et al. Prevention of hepatitis B by immunization of the newborn infant a long-term follow-up study in Stockholm, Sweden. Scand J Infect Dis, 1995, 27(1) p3-7
  7. Margolis HS; Coleman PJ; Brown RE; Mast EE; Sheingold SH; Arevalo JA Prevention of hepatitis B virus transmission by immunization. An economic analysis of current recommendations. JAMA, 1995, 274(15) p1201-8
  8. Kane MA; Hadler SC; Margolis HS; Maynard JE. Routine prenatal screening for hepatitis B surface antigen. JAMA, 1988;259(3):408-9
  9. Jordan R, Law M. An appraisal of the efficacy and cost effectiveness of antenatal screening for hepatitis B. J Med Screen, 1997, 4(3)117-27
  10. Kato H; Nakata K; Hamasaki K et al. Long-term efficacy of immunization against hepatitis B virus in infants at high-risk analyzed by polymerase chain reaction. Vaccine, 1999, 18(7-8) 581-7
  11. McCormack G; Connell J; Staines A et al. Estimation of the prevalence of HBV infection in Ireland using oral fluid samples. IJMS, 2000, Vol 169, Supplement 2, 21.
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