Reviewing evidence

The process of evaluation starts with the meta-analyses of prevention interventions, which we look at in more detail below, as well as other efficacy research. At the next stage, these findings might get translated into recommendations or guidelines for good practice in prevention work. For instance, in the UK the National Institute of Clinical Excellence (NICE) published a set of guidelines called One to one interventions to reduce the transmission of sexually transmitted infections (STIs) including HIV (NICE 2007), which recommended that health professionals working in areas ranging from primary care to schools should:

“Have one to one structured discussions with individuals at high risk of STIs (if trained in sexual health), or arrange for these discussions to take place with a trained practitioner.”

These guidelines also stated that health professionals trained in sexual health should:

“Have one to one structured discussions with individuals at high risk of STIs. The discussions should be structured on the basis of behaviour change theories. They should address factors that can help reduce risk-taking and improve self-efficacy and motivation. Ideally, each session should last at least 15-20 minutes. The number of sessions will depend on individual need.”

These guidelines were based on a review of a number of counselling programmes for people at risk of HIV and STIs (and teenage pregnancy).

At the time of writing, NICE is developing guidance on increasing the uptake of HIV testing among black Africans in England (see http://guidance.nice.org.uk/PHG/Wave19/3) and on increasing the uptake of HIV testing among men who have sex with men (see http://guidance.nice.org.uk/PHG/Wave19/4).The draft documents recommend, amongst other things: having a local strategy for encouraging individuals to consider HIV testing, developed in consultation with local voluntary organisations and community members; the recruitment and training of community members as ‘health champions’ and ‘role models’; increasing testing in non-traditional settings; increasing testing in primary care; and further research.

It is important to emphasise that evidence of efficacy is more easily generated and more available for certain types of intervention (e.g. structured counselling or motivational interviewing) than it is for others (e.g. media interventions). People who are receiving a one-to-one or group intervention are easily identifiable to researchers, can complete a survey or be interviewed, and can be compared to a control group who were not offered the intervention. In the case of media, structural or environmental interventions, it is more difficult to identify both people whom the intervention may have had an impact on and a control group who have not been exposed to the intervention.

It is also important to note that systematic review of the effectiveness of public health interventions is a new area of study. The US Centers for Disease Control was the firstagency in the world ever to attempt to collect and systematise the evidence for the efficacy of different interventions with its Diffusion of Effective Behavioral Interventions (DEBI) project (see ‘The CDC Reviews of Effective Interventions’ below) and NICE in the UK was the second. In other parts of the world, no attempt has been made to meta-analyse the efficacy of different interventions, even when there are enough to provide evidence of differential efficacy.