R.Smyth, E. Keenan, A. Dorman, J. O'Connor
Reprinted from Vol. 164, No.4, October, November,
December, 1995, pp.267-268.
The Drug Treatment Board, McCarthy Centre, 30-31
Pearse Street, Dublin 2.
During a one year period from August 1992 to
August 1993, 272 injecting drug users attending the National Drug Treatment
Centre were tested for antibody to Hepatitis C Virus with a second generation
EIA test. The overall ser-prevalence was 84% (N=229).
A significantly greater proportion of females tested
positive than males (Female: Male, 94% v 80%, p < 0.012). Looking at sero-prevalence
of Hepatitis C in relation to duration of intravenous drug misuse, we found that
in those patients with a duration of misuse of greater than two years drug misuse,
we found that in those patients with a duration of intravenous drug misuse of
less than two years (N=116) the sero-prevalence was 70%.
We conclude that needle sharing continues to occur
among injecting drug users during their first two years of injecting, despite
the existence of harm minimization programmes. Our results would suggest
that female injecting drug users are involved in greater at risk behaviour in
relation to Hepatitis C than their male counterparts.
Infection with Hepatitis C Virus is common among
injecting dug users. Reported sero-prevalences of antibody to Hepatitis C Virus
among injecting drug users include 56% in a German study(1) and 74%
in a Dutch study(2). The parenteral route is a very effective mode
of transmission of Hepatitis C. Consequently injecting drug users, (due to needle
sharing), and haemophiliacs comprise the two groups who are most at risk. Recent
research has supported earlier suspicions that sexual and intrafamilial spread
are poor modes of transmission(3,4).
With the advent of Human Immunodeficiency Virus
(HIV) in the early 1980's much effort has been put into establishing harm minimization
programmes for at risk groups. There has been an intensive drive to educate injecting
drug users regarding sterile injecting techniques and needle exchanges have been
provided. These approaches have been used in Dublin also, needle exchanges having
been established in the late 1980's. These programmes may also reduce new cases
of infection by viruses with a similar mode of transmission to HIV, including
Hepatitis C Virus.
In Ireland the only previous study reporting sero-prevalence
of antibody to Hepatitis C Virus was carried out in the West of Ireland among
patients with liver disorders. This reported a rate of 10.3% mainly associated
with blood transfusions(5).
Our aim was to quantify the sero-prevalence of
antibody to Hepatitis C Virus among injecting drug users attending our Centre
and to ascertain whether the harm minimization programme has made an impact on
All patients, both new attenders and re-attenders, who presented at the National
Drug Treatment Centre, during a one year period between 15 August 1992 and
15 August 1993, giving
a history of injecting drug use, were encouraged to consent to serological
testing. Based on history given by patients, the duration of intravenous misuse
was recorded as the time elapsed, in years and months since the patient first
injected. Data regarding presence of a second risk factor was not obtained.
The risk associated with blood transfusion in a young cohort or tattooing is
very low compared to that associated with drug injecting (6,7).
The test used was the second generation enzyme linked immunosorbant assay (EIA)
for antibody to Hepatitis C virus, produced by Ortho. For each specimen which
tested positive another second generation EIA test for antibody to Hepatitis
C was carried out and in all cases this was also positive. The sensitivity
of second generation EIA tests is high (98%-100%) There is though a lack of
specificity with a risk of false positivity. This is a problem with a low risk
group such as blood donors rather than a high risk group such as intravenous
drug misusers (8). The biggest limitation of the EIA test for antibody
to Hepatitis C Virus is the delay in the appearance of antibody after primary
infection. This delay may be up to six months (9). Consequently
we choose to exclude all patients whose duration of intravenous misuse was
less then six months. Fifteen patients were excluded on this basis. Patients
were then assigned to one of two groups:
Group one if their duration of intravenous drug
misuse was between six months and two years inclusive, and group two if the duration
of intravenous drug misuse exceeded two years. The principal reason for choosing
two years as the cut off point was that we wished group one to consist only of
patients with short duration of intravenous drug misuse whose injecting commenced
after harm minimization programmes were established in Dublin.
A total of 272 patients (194 male) were included
in the study. The mean age of the total study group was 24.5 years and their
mean duration of intravenous drug misuse was 4.5
years. Group one was made up of 116 patients (77 male, mean age 21.6 years, age
range 17-34, modal age 20 years). The mean duration of intravenous drug misuse
was 1.1 years. Group two was made up of 156 patients (117 male, mean aged 26.7
years, age range 18-43 years, modal age 24 years). The mean duration of intravenous
drug misuse was 6.9 years.
The sero-prevalence of antibody to Hepatitis C
Virus among the total study population was 84% (95% Confidence Interval, 80%-88%)
with 229 patients testing positive. The sero-prevalence among group one was 70%
(95% Confidence Interval, 62%-78%) and among group two was 95% (95% Confidence
Interval 92% -99%). See Table 1.
Looking at sex differences and sero-prevalence,
156 of the 194 males (80%) tested positive for antibody to Hepatitis C Virus
and 73 of the 78 females (94%) were positive. This difference was statistically
significant (Chi-squared = 6.302, df=1, p<0.012).
The sero-prevalence for antibody to Hepatitis C
among the total study population is higher than the figures from the German and
Dutch studies. (However both of these studies used first generation EIA which
were slightly less sensitive in detecting antibody to Hepatitis C Virus). The
former study looked at a variety of risk groups but only involved 46 drug users.
The latter study involved 304 injecting drug users and noted that duration of
intravenous misuse, as well as frequency of injecting were associated with increase
risk of infection. As 50% of those who become infected with HCV go on to develop
chronic hepatitis it is felt that this may create a significant burden on general
medical services in the future (10).
We noted with interest the difference in sero-prevalence
rates for antibody to Hepatitis C between male and female intravenous drug misusers
in this study. We have previously reported this(11) and feel that
it indicates more at risk behaviour among female injecting drug users, many of
whom are in relationships with male injecting drug users and consequently share
injecting equipment with their partners.
Our results do indeed show a lower sero-prevalence of antibody to Hepatitis
C Virus among injecting drug users with injecting histories of less than two
years. However the
Comparing sero-prevalence of anti-HCV between two
groups of IVDU with varying durations of intravenous misuse (DIM)
HCV + ve
(Mean DIM 1.1 years)
n = 116
(Mean DIM 6.9 years) n = 156
of 70% among injecting drug users with a mean duration of intravenous
drug misuse of only 1.1 years is a cause for concern. It could
be argued that this figure will rise as their mean duration of
misuse approaches that of group two. Our data indicates that
Hepatitis C Virus is spread very readily by needle sharing and
that needle sharing remains prevalent among injecting drug users
with short histories. Previous researchers have noted that uptake
from needle exchanges tends to be poor among younger injecting
drug users with shorter histories(12,13). Given these
facts we feel that future harm minimization strategies should
focus more directly on those injecting drug users with a shorter
history of injecting and also female injecting drug users.
Now that donated blood can be screened for antibody
to Hepatitis C Virus one can expect that the incidence of post transfusion hepatitis
C will decrease and that in future haemophiliacs will be at reduced risk(6).
However if injecting drug users continue to indulge in at risk behaviour the
incidence of Hepatitis C Virus among intravenous drug misusers will remain high.
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