Is there a role for abstinence only programmes for HIV prevention in high income countries?

The systematic review in this week's BMJ by Underhill and colleagues brings valuable insights to a highly contentious issue: whether abstinence only (as opposed to abstinence plus) programmes can stop, delay, or decrease sexual activity and prevent HIV infection.1 This question is important because 38 million people are currently infected with HIV but, despite 25 years of research, we still have no vaccines to prevent HIV infection. Furthermore, HIV prevention has become a politically charged issue because funds from the US President's Emergency Plan for AIDS Relief (PEPFAR) can be used for abstinence only programmes, but cannot be used for other safer sex strategies, needle exchange, or instructions for using condoms. Is this an effective use of public funds?2

A previous review of abstinence only programmes in the developing world, presented at the 2006 international AIDS meeting,3 found little evidence that they were effective in changing sexual behaviour and preventing HIV infection, either because of weak study designs or the difficulty in measuring outcomes of interest, although these programmes did seem to change knowledge, beliefs, and intentions to delay sex or to use condoms if they had sex, if not actual behaviour.

The systematic review by Underhill and colleagues focuses on the effect of such programmes in the developed world.1 As the authors point out, in theory such programmes should be more effective in high income populations where people are more likely to be able to decide freely whether and how they have sex. Previous reviews of the effectiveness of abstinence only interventions in high income settings have reported divergent conclusions. However, the current study has more rigorous methodology (including use of a prereviewed Cochrane protocol), it includes published and unpublished studies plus data from many countries, and it focuses on abstinence only and behavioural and biological outcomes related to HIV prevention.

The results of the review make it clear why it has been difficult to show unequivocally that abstinence only programmes are ineffectual in all settings. The authors identified 13 randomised studies that met the inclusion criteria, but a formal meta-analysis could not be performed because of high heterogeneity in both the abstinence programmes and study end points. The intervention programmes studied varied greatly in their content and length, while control groups varied between no treatment and numerous usual care programmes. The studies' methodological quality was difficult to assess. All trials conducted an analysis of completed cases only instead of the more rigorous intention to treat analysis.

Most sexual behaviour outcomes were limited to vaginal sex, and did not assess oral, anal, or same sex behaviour. All outcomes were self reported. No trial assessed the incidence of HIV—the outcome of real interest. All assessed surrogates including self reported sexually transmitted infections or pregnancy. Furthermore, although Underhill and colleagues searched for studies from all developed countries, all of their included studies enrolled adolescents in the United States, and this limits the generalisability of the review to other populations.

Importantly, however, despite this heterogeneity, the results of the included studies (with more than 15 900 participants) were remarkably consistent. When compared with various control groups, there was little evidence that risky sexual behaviour, incidence of sexually transmitted infections, or pregnancy were reduced in adolescents in abstinence only programmes. Abstinence only programmes did not increase primary abstinence (prevention) or secondary abstinence (decreased incidence and frequency of recent sex).

In contrast to abstinence only programmes, programmes that promote the use of condoms greatly reduce the risk of acquiring HIV,4 5 6 especially when such programmes are culturally tailored behavioural interventions targeting people at highest risk of HIV infection. Therefore, in the United States priority should be given to culturally sensitive, sex specific, behavioural interventions that target black and Hispanic patients in clinics for sexually transmitted infections, men who have sex with men, and adolescents being treated for drug misuse who are at highest risk of acquiring HIV.7 8

In the developing world (especially in African countries), the overwhelming lack of resources initially made abstinence only programmes popular. However, the increasing availability of condoms means that condom use has become a feasible alternative.9 While reducing the number of sexual partners may have been important in the recent reduction of HIV incidence in Uganda and Thailand,10 the relative contributions of the components of the “ABC” approach of increased abstinence, reducing the numbers of sexual partners (with the “B” standing for “be faithful”), and increased condom use remains unknown.11 12