BMJ 2000;320:512 ( 19 February )

Letters

Accuracy of perceptions of hepatitis B and C status - Results require further clarification

Ali Judd , research associate. Gerry V Stimson , professor.  Matthew Hickman , principal research fellow. Department of Social Science and Medicine, Imperial College School of Medicine, London W2 1PG, John Macleod , clinical research fellow. Department of General Practice and Primary Care, University of Birmingham, Birmingham B15 2TT

EDITOR - We agree with Best et al that knowledge of hepatitis B and C viral status is important for injecting drug users, in the context of both the users' health and the health of others.¹ The authors' short report, however, provided little clarification of the issues concerned.

The authors describe applying "virus tests" for hepatitis B and C to the blood they collected. Was the blood actually tested for hepatitis B and C virus (antigen)? As one response in the eBMJ has already pointed out, this is unlikely given the prohibitive cost of the nucleic acid amplification assays involved.² More probably the blood was tested for serological markers (antibody) indicative of past exposure. Results of such tests require careful interpretation, and confusion is still widespread.³

Users were asked about their "viral status." Again it is unclear if this refers to antigen or antibody status. The two have very different implications in individual and public health terms, and between the two viruses. Roughly three quarters of people infected with hepatitis C virus will become chronic carriers, in contrast to less than a tenth of those infected with hepatitis B virus. Previously tested users who were antibody positive but antigen negative and who described themselves as "negative" were arguably correctly interpreting their status, at least for hepatitis B. Another possibility is that their status had changed since they were last tested. The authors also describe self assessment of viral status in users never previously tested. The fact that some users guessed wrong may not be surprising.

The authors conclude that "clinicians must be more vigorous in encouraging drug users to reduce risk behaviours." Certainly, communication of harm reduction messages is important and requires sustained effort. There is some encouraging evidence that such messages may have an impact. ^{4 5}

Ali Judd , research associate. 
a.judd@ic.ac.uk

Gerry V Stimson , professor. 
Matthew Hickman , principal research fellow. 
Department of Social Science and Medicine, Imperial College School of Medicine, London W2 1PG

John Macleod , clinical research fellow. 
Department of General Practice and Primary Care, University of Birmingham, Birmingham B15 2TT

 

1.	Best D, Noble A, Finch E, Gossop M, Sidwell C, Strang J. Accuracy of perceptions of hepatitis B and C status: cross sectional investigation of opiate addicts in treatment. BMJ 1999; 319: 290-291 [Full Text] . (31 July.)
2.	Moss PJ. Perceptions of hepatitis B and C status: how should positive and negative results be interpreted? eBMJ 1999;319. (www.bmj.com/cgi/eletters/319/7205/290#EL1)
3.	Gilson RJC. Hepatitis B and admission to medical school. BMJ 1996; 313: 830-831 [Full Text] .
4.	Judd A, Hickman M, Renton A, Stimson GV. Hepatitis C virus infection among injecting drug users: has harm reduction worked? Addict Res 1999; 7: 1-6 .
5.	Stimson GV. Has the United Kingdom averted an epidemic of HIV-1 infection among drug injectors? Addiction 1996; 91: 1085-1099 [Medline] .