Accuracy of perceptions of hepatitis B and C status: cross sectional investigation of opiate addicts in treatment

Subjects, methods, and results

We collected data on 106 injecting opiate addicts attending a methadone maintenance clinic in London. Sufficient blood was obtained for 90 hepatitis C virus tests and for 84 hepatitis B virus tests (when blood was insufficient, priority was given to hepatitis C). We present data for the 90 addicts from whom blood was obtained.

The participants' mean age was 36 years (range 21-54), and 69 were men. They had attended the clinic for an average of 2.4 years and received a mean methadone dose of 72 mg (range 15-150 mg). Their mean age at first opiate injection was 21 and the mean duration of injecting was 15 years. Fifty nine had used a syringe after someone else, and 68 had shared injecting paraphernalia.

Seventy seven were positive for hepatitis C virus, and 46 were positive for hepatitis B virus. Of the 79 who reported having previously been tested for hepatitis C virus, 58 thought they were positive, 16 thought they were negative (of whom half were wrong), and five were uncertain. Of the 70 addicts previously tested for hepatitis C virus whom we found to be positive, 12 did not know or were wrong about their status (see table) Of the 41 previously tested for hepatitis B virus whom we found to be positive, 16 thought themselves to be negative.

Of the 11 addicts never previously tested for hepatitis C virus, four were correct in their self assessment (one positive, three negative), four incorrectly thought they were negative, and three did not know Of the 22 addicts not previously tested for hepatitis B virus, six were correct in their self assessment (all negative), while three mistakenly believed they were positive and one negative, and 12 could not report their viral status (five positive, seven negative).

Subjects never previously tested for hepatitis B virus were less likely to be seropositive (5/22 v 41/62; χ²=10.66, df=1, P<0.005). A similar pattern was seen for hepatitis C virus positivity (7/11 v 70/79; χ²=3.06, df=1, P<0.10). Of the 33 addicts not previously tested for hepatitis B or hepatitis C virus, only 10 accurately perceived their combined status.

Discussion

Our finding of 86% seropositivity for hepatitis C virus is consistent with the 67% found among Australian injecting drug users1 and 75% among UK addicts receiving maintenance treatment.3 The participants' perceptions of their viral status were often inaccurate: for both hepatitis B and hepatitis C virus, they tended to believe they were negative when they were positive. If untested drug users assume they are positive and act accordingly they pose no threat to public health. If they mistakenly presume negative status, this may have serious public health consequences. Clinicians should encourage testing in all patients who are injecting drug users and use this as a catalyst for interventions. As Crofts et al point out,1 drug treatment alone is not sufficient in reducing hepatitis seroconversion and clinicians must be more vigorous in encouraging drug users to reduce risk behaviours.