Large gaps in the HIV prevention evidence base

An analysis of research that is relevant to HIV prevention in the United Kingdom has identified several important topics on which little research is done. Writing in the journal BMC Public Health, the authors point to the lack of studies into combination prevention packages, individuals with undiagnosed infection, the impact of social policy and the implementation of interventions that have been successful in other countries. It is rare for the impact of mass media campaigns to be evaluated.

The authors say that although innovative, evidence-based approaches are needed in HIV prevention, large areas of interest are under-researched.

The analysis was conducted by the National Institute of Health Research Evaluation Trials and Studies Coordinating Centre, whose staff searched databases for studies conducted between 2006 and 2009 in the UK, United States, Canada, Australia and New Zealand. (Studies conducted in European countries were excluded).

They identified 868 relevant systematic reviews, randomised controlled trials, cohort studies, case-control studies and surveys. They then categorised them both in terms of the activities or topics they dealt with, and the social groups studied.

The most widely studied areas were:

• Intervention technologies, such as circumcision, pre-exposure prophylaxis, condoms, the use of HIV treatment to reduce infectivity and needle exchange (216 studies).
• The investigation of sexual or risk-taking behaviour and studies of interventions which aim to change behaviour (206 studies).
• Descriptive epidemiology: studies seeking to understand the distribution of disease in populations and the association of infection with age, socio-economic groups and sexual activities (162 studies).

Nonetheless the authors didn’t look in detail at the studies or attempt to assess their quality. They say that even when there are a significant number of publications on a topic, this “does not necessarily equate to high quality, robust research or provide evidence that translates to effective prevention.”

Moreover a number of under-researched areas were identified:

• Undiagnosed infection: better understanding of the characteristics of people with undiagnosed infection, interventions which aim to reach these individuals and understanding of the barriers to HIV testing. Only four papers were identified which covered this area, mostly conducted with gay men.
• Research which tests the ability of an intervention that has been successful in one place to be repeated, translated or adapted in a new setting. Only three studies were found. However the authors note that since most HIV prevention research comes from the United States, we need to know if approaches developed there are as effective in other contexts.
• Studies on policies, laws or ethical issues which impact on HIV prevention. This would include prosecutions of HIV transmission, but despite this having become a key issue in recent years, only three studies were identified.
• Combination prevention: when more than one prevention intervention is provided in combination, for example when sexually transmitted infection screening is provided together with an educational intervention. Ten studies were categorised as addressing this issue, but only two actually evaluated the added value of putting interventions together.
• Studies covering social factors that impact on HIV (e.g. education or housing), structural interventions which address social factors, and research into stigma and discrimination. A total of 26 studies were identified.
• Educational interventions, including campaigns, social marketing, leaflets, videos and school-based work. The researchers expected to find more than 28 studies in this area; they were particularly surprised to identify only two studies of the impact of mass-media campaigns.

In terms of the risk groups most often researched, these were people with diagnosed HIV, drug and alcohol users, men who have sex with men, and young people.

Less research is conducted specifically with older people, transgender people, sex workers, heterosexuals (especially heterosexual men), non-black ethnic groups and people who are socially excluded.

The authors say that they would welcome suggestions for research that would help fill the gaps in the evidence base.