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The changing age distribution of men who have sex with men diagnosed with HIV in Victoria

Carol El-Hayek, Isabel Bergeri, Margaret E Hellard, Alisa E Pedrana, Nasra Higgins, Alan Breschkin and Mark Stoové
Med J Aust 2010; 193 (11): 655-658. || doi: 10.5694/j.1326-5377.2010.tb04095.x
Published online: 6 December 2010

Abstract

Objective: To describe recent trends among men who have sex with men (MSM) in age at diagnosis of HIV in Victoria.

Design and setting: Analysis of Victorian HIV surveillance data from (i) passive surveillance (2000–2009) and (ii) the Victorian Primary Care Network for Sentinel Surveillance (VPCNSS) (2006–2009). Age-trend comparisons were made using syphilis and gonorrhoea enhanced surveillance.

Main outcome measures: HIV diagnoses, HIV testing and behavioural indicators by year and age group among MSM.

Results: Following a period of sustained increase between 2000 and 2007, the median age at HIV diagnosis among MSM declined significantly, from 38.8 years in 2007 to 35.3 years in 2008 (P = 0.023), remaining at 35.9 years in 2009. Between 2007 and 2008, the median age of syphilis and gonorrhoea notifications also declined, from 40.6 to 36.0 years and from 32.3 to 29.3 years, respectively. The median age of HIV testing among MSM in the VPCNSS population remained constant between 2006 and 2009, at 33.0 years. Compared with older MSM, those aged less than 35 years were more likely to have never previously been tested for HIV (relative risk [RR], 1.36 [95% CI, 1.30–1.41]); to not know the HIV status of their regular partner (RR, 1.11 [95% CI, 1.01–1.21]); and to report inconsistent condom use with casual partners (RR, 1.07 [95% CI, 1.01–1.14]) and regular partners (RR, 1.07 [95% CI, 1.00–1.14]).

Conclusions: Younger MSM in Victoria may be at increasing risk of HIV infection. Enhanced methods of monitoring HIV and sexually transmitted infection transmission in younger MSM are needed, as well as prevention messages to target this group, who may not fully understand their HIV risk.

HIV diagnoses declined in Australia during the 1990s, only to increase again through the 2000s, with men who have sex with men (MSM) continuing to be the group at greatest risk. Increased rates of HIV diagnosis have been greater in Victoria than in other states.1,2 Multiple factors are thought to be contributing to this increase, including increased rates of unprotected anal intercourse among MSM,3 an increase in other sexually transmitted infections (STIs) that facilitate HIV transmission,4,5 and increased numbers of sexually active HIV-positive MSM since the introduction of highly active antiretroviral treatment (HAART).6

Over the years, there has been an increase in the age at HIV diagnosis among MSM in Victoria,7 as would be expected given reported similarities in age within MSM sexual networks.8 Despite this trend, there has been ongoing concern about the potential risk of acquiring and transmitting HIV among younger MSM because, compared with older MSM, they have less frequent testing for HIV and STIs9 and are less likely to know their HIV status and that of their partner.10,11

In this article we report on recent trends from Victorian passive HIV surveillance and the Victorian Primary Care Network for Sentinel Surveillance (VPCNSS) that suggest younger MSM in Victoria are at increasing risk of HIV infection.

Methods
Victorian Primary Care Network for Sentinel Surveillance

The VPCNSS is a network of clinical sites participating in the surveillance of HIV, syphilis, chlamydia and/or hepatitis C.12 The HIV network sites include sexual health and gay men’s health clinics with a high case load of MSM. These sites notified about 52% of all new HIV diagnoses in Victoria in 2008 (unpublished data, Burnet Institute, 2010). Demographic and risk behaviour information are collected from MSM undergoing routine testing for HIV and linked with their test result using a unique identifier.

Results
Discussion

In 2008, we observed a significant decline in the median age of MSM diagnosed with HIV in Victoria. This decline in age, which continued into 2009, is the first observed in Australia since the introduction of HAART. The decline in the median age of MSM recently acquiring HIV suggests recent increases in HIV transmissions (as distinct from diagnoses) and risky behaviour among younger MSM. Syphilis and gonorrhoea notification rates also increased among younger MSM. These STIs are considered markers of risky sexual behaviour,13 and may provide early indicators of HIV trends because they are more infectious14 and commonly symptomatic, thus encouraging testing.15

Although the VPCNSS testing data are biased by health-seeking behaviour, the data showed no change in the median age of MSM tested between 2006 and 2009. While this finding suggests that reductions in age at HIV diagnosis may not be an artefact of younger MSM testing for HIV, it may also be the case that younger MSM were being tested at other non-VPCNSS sites. Assertions regarding overall testing trends in this group are difficult given that statewide HIV testing data lack information about the reasons for testing or the characteristics of those tested.

Examination of self-reported behavioural data from the VPCNSS showed little difference across age groups in the reported number of sexual partners. Younger gay men were slightly more likely to engage in risky sexual behaviour and to be unaware of their partner’s serostatus, and were more likely to have never previously been tested for HIV. These findings are consistent with other behavioural and epidemiological data relating to testing history and knowledge of partner serostatus.9-11

In addition, recent focus group data have shown that younger MSM are less likely to discuss HIV and other STIs with peers (Burnet Institute, unpublished data). It has also been suggested that younger gay men may be more susceptible to engaging in risky sexual behaviour because they are less aware of or less concerned about the implications of HIV since the introduction of HAART.16

As the observations reported here occurred in a limited time frame and represent a relatively small number of cases, we cannot rule out a clustering of infections within younger MSM sexual networks being responsible for the declining age at HIV diagnosis. On the other hand, if these data represent a turning point in HIV epidemiology, a number of implications emerge.

First, the potential diversification of the epidemic within the primary at-risk group highlights the importance of ongoing research and surveillance of future trends. While routine surveillance data are important to monitor changes in epidemiology, more detailed and mixed-method approaches would provide a better understanding of what is driving epidemiological changes and inform the development or refinement of public health interventions. Second, deciding when and how to respond to increasing HIV diagnoses in younger MSM is difficult. The concordance of surveillance data on age at diagnosis of HIV and other STIs suggests that a response may be needed in the short term. Such a response would need to consider more diverse health promotion strategies to ensure that prevention messages reach young MSM.

3 Selected characteristics of MSM presenting for HIV testing at VPCNSS HIV clinics, by age group, April 2006 to June 2009

Characteristic

< 35 years*

≥ 35 years*

RR (95% CI)


Total MSM tested

9379 (56.4)

7240 (43.6)

Tested positive for HIV

142 (1.5)

157 (2.2)

Survey data (response rate)

8786 (93.7)

6701 (92.6)

Reason for test

Asymptomatic screen

6746 (83.8)

5360 (85.2)

1.0

STI symptoms

1302 (16.2)

932 (14.8)

1.05 (1.01–1.09)

Time since previous negative HIV test

< 1 year

3261 (41.1)

2449 (41.5)

1.0

≥ 1 year

3936 (49.6)

3221 (54.6)

0.97 (0.94–1.00)

Never previously tested

746 (9.4)

226 (3.8)

1.36 (1.30–1.41)

Number of anal sex partners in previous 6 months

None

176 (6.1)

502 (14.0)

0.54 (0.48–0.62)

1–5

2020 (70.4)

2206 (61.6)

1.0

≥ 6

673 (23.5)

876 (24.4)

0.91 (0.85–0.97)

HIV status of regular partner

Negative

1072 (68.9)

1296 (67.7)

1.0

Positive

165 (10.6)

303 (15.8)

0.78 (0.68–0.89)

Don’t know

318 (20.5)

316 (16.5)

1.11 (1.01–1.21)

Condom use with regular partner

Always

848 (44.2)

1004 (47.3)

1.0

Inconsistent

1071 (55.8)

1118 (52.7)

1.07 (1.00–1.14)

Condom use with casual partners

Always

1389 (63.9)

1759 (66.8)

1.0

Inconsistent

786 (36.1)

876 (33.2)

1.07 (1.01–1.14)


MSM = men who have sex with men. RR = relative risk. STI = sexually transmitted infection. VPCNSS = Victorian Primary Care Network for Sentinel Surveillance. * Data are number (%). Some data were missing in each category. Missing data were excluded from percentage calculations. Univariate analysis. Represents only men tested and surveyed at the gay men’s health clinics.

  • Carol El-Hayek1
  • Isabel Bergeri1
  • Margaret E Hellard1
  • Alisa E Pedrana1,2
  • Nasra Higgins3
  • Alan Breschkin4
  • Mark Stoové1

  • 1 Centre for Population Health, Burnet Institute, Melbourne, VIC.
  • 2 Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC.
  • 3 Communicable Disease Prevention and Control Unit, Victorian Government Department of Health, Melbourne, VIC.
  • 4 Victorian Infectious Diseases Reference Laboratory, Melbourne, VIC.


Correspondence: carol@burnet.edu.au

Acknowledgements: 

We would like to acknowledge the ongoing contribution of the surveillance officers at the Burnet Institute and the notifying medical practitioners. Special thanks to the partner notification officers for their important role in the HIV/STI notification process, and to the sentinel sites and laboratories that undertake pathology services for the VCPNSS clinics. We are grateful for the financial support received from the Victorian Department of Health.

Competing interests:

The Centre for Population Health at the Burnet Institute is contracted by the Victorian Department of Health to manage HIV passive surveillance (since 1991) and HIV, other STIs and hepatitis C sentinel surveillance (since 2006) in Victoria. Data from these surveillance systems form the basis of our article.

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