HIV/Sexually Transmitted Infections (STIs) |
Published on: 29 July 2011 |
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Unlinked anonymous HIV and viral hepatitis monitoring among IDUs: 2011 update
Unlinked anonymous HIV and viral hepatitis monitoring among IDUs: 2011 update
New data from the ongoing Unlinked Anonymous Monitoring Survey of HIV and Viral Hepatitis among Injecting Drug Users - extending the available data up to 2010 - have been published on the HPA website; the updated set of tables presents data from the survey for the period 2000 to 2010 inclusive [1]. Data for 1990 to 1999 inclusive can be found in last years data tables [2].
The tables include, in addition to data for the whole of England, Wales and Northern Ireland (the areas covered by this survey), data tables for each country and the regions of England.
This article presents an overview of the trends between 2000 and 2010 for HIV, hepatitis B and risk behaviours; also summarised here are data from the survey reported in the HPA's newly published Hepatitis C in the UK: 2011 report [3].
HIV transmission in IDUs
The 2010 prevalence of HIV among the IDUs taking part in the survey across England, Wales and Northern Ireland was 1.1% (95% CI, 0. 73%-1.4%). Between 2000 and 2010, prevalence varied between 0.76% and 1.6% (see figure 1; and table 1 of the dataset). In 2010 no HIV infections were detected in Wales (0%, 95% CI: 0%-1.9%) or Northern Ireland (0%, 95% CI: 0%-1.9%). In England the HIV prevalence was 1.2% (95% CI: 0.81%-1.6%) in 2010; this is significantly higher than in 2000 when the prevalence was 0.78% (see figure 1; and statistical note a). HIV prevalence among the IDUs taking part in the survey in England was also significantly higher in 2005, 2008 and 2009 than in 2000.
The HIV prevalence among the recent initiates to injecting drug use (those who first injected during the preceding three years) is an indicator of recent transmission. The prevalence of anti-HIV among the recent initiates taking part in the survey across England, Wales and Northern Ireland has varied over time and has ranged from no infections detected in this group in 2000 to a prevalence of 1.3% in 2008. The 2010 prevalence in this group was 0.5% (95% CI: 0.19%-1.2%; see figure 1; table 23 of the dataset; and statistical note b) and is similar to that found in 2009. This finding indicates that HIV transmission is continuing to occur among IDUs.
Uptake of voluntary confidential testing (VCT) for HIV among the survey participants across England, Wales and Northern Ireland has increased significantly since 2000; rising from 52% in 2000 to 75% in 2010 (see figure 1; table 7 of the dataset; and statistical note c). Uptake of VCT for HIV increased in all age groups, but had risen most among those aged under 25 years where uptake increased from 37% in 2000 to 65% in 2010 (see table 7 of the dataset). The proportion of the participants with antibodies to HIV, who answered the questions on the uptake of VCT for HIV, reporting that they were aware of their HIV infection was 89% in 2010. This was the highest level of awareness of HIV infection reported since the survey began [2].
Figure 1. Prevalence of anti-HIV and uptake of voluntary confidential testing for HIV among participants in the Unlinked Anonymous Monitoring Survey of IDUs: England, Wales and Northern Ireland 2000-2010
Hepatitis B and vaccine uptake
The prevalence of anti-HBc (a marker of past or current infection with hepatitis B) among the survey participants across England, Wales and Northern Ireland has declined since 2004. During the period 2000 to 2004 the anti-HBc prevalence fluctuated between 28% and 30%, before declining to 16% in 2010 (see figure 2; table 2 of the dataset; and statistical note d).
The survey also monitors, through self-reports, the uptake of hepatitis B vaccine. Vaccine uptake among the survey participants has increased from 35% in 2000 to 74% in 2010 (see figure 2; table 6 of the dataset; and statistical note e).
Together, these findings suggest that the increase in the uptake of the hepatitis B vaccine is now having an impact on hepatitis B transmission among IDUs. The decline in the prevalence of anti-HBc among IDUs might also reflect the recent fall in the levels of reported injecting equipment sharing from 31% in 2000 to 21% in 2010 (see table 4 of the dataset; and statistical note f). However, the prevalence of anti-HBc among the recent initiates taking part in the survey has fluctuated over time since 2000 (between 3.1% and 14%) with no clear trend over time (see figure 2; table 23 of the dataset; and statistical note g). This finding indicates that hepatitis B infections are continuing to occur among IDUs - though this may be focused among recent initiates - suggesting a possible need to improve access to hepatitis B vaccine and other preventive support for those who have recently started injecting.
Figure 2. Prevalence of anti-HBc and levels of self-reported hepatitis B vaccine uptake among participants in the Unlinked Anonymous Monitoring Survey of IDUs: England, Wales and Northern Ireland 2000-2010
Hepatitis C: one half of IDUs in England have antibodies
The prevalence of antibodies to hepatitis C virus (anti-HCV) among the survey participants across England, Wales and Northern Ireland has increased significantly from 38% in 2000 to 47% in 2010 (see figure 3; table 3 of the dataset; and statistical note h). However, whilst this increase is significant, anti-HCV prevalence among IDUs still remains much lower than in the early 1990s when prevalence was over 60% [4].
The prevalence of anti-HCV among the recent initiates taking part in the survey has been stable in recent years, but remains higher than it was in 2000 (see figure 3; table 23 of the dataset; and statistical note i). Uptake of VCT for hepatitis C among the survey participants has increased significantly since 2000 rising from 49% in 2000 to 82% in 2010 (see figure 3; table 8 of the dataset; and statistical note j).
Figure 3. Prevalence of anti-HCV and uptake of voluntary confidential testing for hepatitis C among participants in the Unlinked Anonymous Monitoring Survey of IDUs: England, Wales and Northern Ireland 2000-2010
Behavioural factors
In 2010 three-quarters (75%) of the participants reported having anal or vaginal sex during the preceding year, this level has changed little over time (see table 10 of the dataset). Of those who had sex in the last year 44% reported having had two or more sexual partners during that time in 2010, and of these only 22% reported always using condoms for anal or vaginal sex (see table 10 of the dataset).
Behaviours were found to vary across the country with needle and syringe sharing ranging from 12% in West Midland region to 31% in the South West region (table 1, see tables 11 to 22 of the dataset). Always using condoms among those with two or more (anal or vaginal) sexual partners in preceding year varied from 7.9% in the East Midlands region to 42% in the East of England region (table 1, see tables 11 to 22 of the dataset).
Table 1. Regional prevalence of needle and syringe sharing and condom use among participants in the Unlinked Anonymous Monitoring Survey of IDUs in 2010
Country or region |
Sharing of needles and syringes among those who had injected in preceding four weeks |
Always using a condom among those with two or more (anal or vaginal) sexual partners in preceding year |
England |
21% |
21% |
East of England |
29% |
42% |
London |
25% |
26% |
South East |
21% |
15% |
South West |
31% |
20% |
West Midlands |
12% |
22% |
North West |
15% |
26% |
Yorkshire & Humber |
23% |
21% |
East Midlands |
18% |
7.9% |
North East |
21% |
23% |
Wales |
20% |
27% |
Northern Ireland |
23% |
35% |
Conclusion
In conclusion, the findings from the Unlinked Anonymous Monitoring Survey of IDUs indicate that hepatitis B prevalence among IDUs is most probably declining - possibly due to increased uptake of hepatitis B vaccine and reduced needle and syringe sharing. However, whilst the prevalences of HIV and hepatitis C among IDUs currently appear to be stable, they both remain significantly higher than in 2000. This indicates that unsafe injecting continues to be a problem and that there is a need to maintain and strength public health interventions that aim to reduce injection related risk behaviours. The impact of public health interventions which aim to prevent HIV and hepatitis C infection through injecting drug use, such as needle and syringe programmes [4] and opiate substitution therapy [5], have been shown to be dependent on their coverage [6-8]. These finding thus suggest a need to review and improve the current coverage of these interventions.
References
1. Health Protection Agency, Health Protection Services and Microbiology Services. Unlinked Anonymous Monitoring Survey of Injecting Drug Users in Contact with Specialist Services: data tables. July 2011. www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1202115519183
2. Health Protection Agency, Centre for Infections. Unlinked Anonymous Monitoring Survey of Injecting Drug Users in Contact with Specialist Services: data tables. July 2010. www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1254510660636
3. Hepatitis C in the UK: 2011 report [2.4 MB PDF]. London: Health Protection Agency, July 2011. Downloadable from the HPA website: Home > Publications > Infectious diseases > Bloodborne infections.
4. Needle and syringe programmes: providing people who inject drugs with injecting equipment. NICE, Public Health Guidance, PH18, February 2009. http://guidance.nice.org.uk/PH18.
5. Drug misuse and dependence - guidelines on clinical management: update 2007. London: Department of Health, 2007.
6. Van Den Berg C, Smit C, Van Brussel G, et al. Full participation in harm reduction programmes is associated with decreased risk for human immunodeficiency virus and hepatitis C virus: evidence from the Amsterdam Cohort Studies among drug users. Addiction 2007; 102:1454-1462.
7. Craine N, Hickman M, Parry JV, Smith J, Walker AM, Russel B, Nix B, May M, McDonald T, Lyons M. Incidence of hepatitis C in drug injectors: the role of homelessness, opiate substitution treatment, equipment sharing, and community size. Epidemiol Infect. 2009;137:1255-1265.
8. Hope VD, Hickman M, Ngui SL, Jones S, Telfer M, Bizzarri M, Ncube F, Parry JV. Measuring the incidence, prevalence, and genetic relatedness of hepatitis C infections among community recruited sample of injecting drug users using dried blood spots. Journal of Viral Hepatitis, 2011 Apr;18:262-70.
Statistical notes
a) After adjusting for age, gender and region of recruitment in a multi-variable analysis, the odds ratio for 2010 was 1.86 [95% CI: 1.09-3.19] compared to 1.0 in 2000;
b) After adjusting for age, gender, and London v. elsewhere in a multi-variable analysis the prevalence did not vary between 2001 and 2010, with an odds ratio of 1.34 [95% CI: 0.19-9.55] in 2010 compared to 1.0 in 2001.
c) After adjusting for age, gender and region of recruitment in a multi-variable analysis, the odds ratio for 2010 was 2.72 [95% CI: 2.43-3.05] compared to 1.0 in 2000;
d) After adjusting for age, gender and region of recruitment in a multi-variable analysis, the odds ratio for 2010 was 0.37 [95% CI: 0.31-0.43] compared to 1.0 in 2000, with prevalence being significantly lower than in 2000 since 2005;
e) After adjusting for age, gender and region of recruitment in a multi-variable analysis, the odds ratio for 2010 was 6.48 [95% CI: 5.79-7.27] compared to 1.0 in 2000;
f) After adjusting for age, gender and region of recruitment in a multi-variable analysis, the odds ratio for 2010 was 0.65 [95% CI: 0.55-0.76] compared to 1.0 in 2000, with sharing also lower than in 2000 in 2004 and between 2006 and 2009;
g) After adjusting for age, gender, and region of recruitment in a multi-variable analysis the prevalence in 2010 was not significantly different from 2000, odds ratio was 0.70 [95% CI: 0.45-1.08] compared to 1.0 in 2000, prevalence was however significantly lower than in 2000 between 2007 and 2009;
h) After adjusting for age, gender and region of recruitment in a multi-variable analysis, the odds ratio for 2010 was 1.19 [95% CI: 1.06-1.35] compared to 1.0 in 2000, with prevalence higher than in 2000 in all years except 2001, 2002 and 2008;
i) After adjusting for age, gender, and region of recruitment in a multi-variable analysis the odds ratio for 2010 was 2.24 [95% CI: 1.64-3.06] compared to 1.0 in 2000, with prevalence higher than in 2000 in all years except 2002 and 2005;
j) After adjusting for age, gender and region of recruitment in a multi-variable analysis, the odds ratio for 2010 was 4.63 [95% CI: 4.10-5.24] compared to 1.0 in 2000.
Corrigendum: HIV-STIs report in HPR 5(17), 29 April 2011
In Trends in genital herpes and genital warts infections, United Kingdom: 2000 to 2009, published 29 April 2011, Volume 5 Number 17, more accurate versions of figures 1 and 6 have been substituted in the archived version, see: http://www.hpa.org.uk/hpr/archives/2011/hpr1711.pdf [270 kb PDF]