This review evaluated interventions for preventing the acquisition, transmission or complications of sexually transmitted infections (STI). The authors concluded that many interventions have been shown to be effective against STIs but few have been widely implemented or evaluated in a range of settings. The conclusions should be treated with caution because of a risk that relevant studies could have been missed.

To determine the effectiveness of interventions for the prevention of sexually transmitted infections (STIs).

MEDLINE and the Cochrane CENTRAL Register for material published in English or presented up to the end of 2003. The reference lists of included publications were also checked. Two studies known to the authors, but not found by the literature search, were also included.

Study designs of evaluations included in the review

Only randomised controlled trials (RCTs) were eligible according to the inclusion criteria and listed among the included studies. The results of some non-randomised trials were discussed separately in the narrative synthesis.

Specific interventions included in the review

All types of preventive intervention at the individual, group and community level were eligible for inclusion. The interventions used in the included studies were classified as behaviour change, vaccination, use of topical microbicides, and prophylactic, curative or suppressive therapy.

Participants included in the review

No inclusion criteria for the participants were specified. The participants in the included studies were heterosexual and homosexual men and women. They were recruited from population samples that included people attending STI clinics and their partners, sex workers and the general population. Most of the included studies were conducted in the USA, Africa, Asia or Europe.

Outcomes assessed in the review

The studies were required to evaluate an objective measure related to the prevention of STI acquisition, transmission or complications. Most of the included studies assessed acquisition of STIs or incident infection rates. Some studies assessed intermediate outcomes such as condom use and STI screening.

How were decisions on the relevance of primary studies made?

The authors did not state how the studies were selected for the review, or how many reviewers performed the selection.

The studies were assessed for appropriateness of analysis and internal and external validity using criteria developed by the U.S. Preventive Services Task Force. The authors did not state how many reviewers performed the validity assessment.

The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction. Data were extracted on the study population, participation and follow-up rates, intervention methods and outcomes. The outcomes were presented as statistically significant or non significant differences between groups, or as hazard ratios, risk ratios or odds ratios with 95% confidence intervals.

How were the studies combined?

The studies were combined in a narrative based on level of intervention (individual, group or community), objective (prevention of acquisition, transmission or complications) and type of intervention.

How were differences between studies investigated?

Differences between the studies were discussed in the text of the review.

Forty-one RCTs with 104,623 potential participants were included. Five of these with 49,155 potential participants were randomised by community. Some non-randomised trials were also included in the results.

Of the 41 included RCTs, 22 showed a significant positive effect of the intervention. Interventions showing a positive effect in more than one study were group counselling and skills building, hepatitis B vaccine, nonoxynol-9 and prophylactic microbicide treatment to prevent acquisition, and partner treatment to prevent transmission. Only one intervention (syndromic treatment of STIs) showed a positive effect in reducing the sexual transmission of the human immunodeficiency virus.

Many interventions have been shown to be effective against STIs but few have been widely implemented or evaluated in a range of settings.

The review addressed a clear question and the inclusion criteria, where specified, were clear. However, the synthesis included a discussion of study designs and outcomes other than those specified, which suggests that the selection of studies for inclusion could have been affected by subjective decisions. The authors searched a relatively narrow range of sources for publications in English only, so relevant studies could have been missed; the fact that studies known to the authors were not found by the search supports this hypothesis. Publication bias was not assessed. The included RCTs were assessed for validity and relevant details of the studies were presented. The risk of introducing bias and errors during the review process cannot be evaluated because the methods used for the study selection, validity assessment and data extraction processes were not reported. The decision to present a narrative synthesis was appropriate and the grouping of studies appeared logical. The authors' conclusions were cautious and followed from the evidence presented. However, in view of the methodological issues discussed above, the conclusions should be treated with caution.

Practice: The authors did not state any implications for practice.

Research: The authors stated that public health agencies should evaluate the effectiveness of successful interventions during scale-up and implementation in new settings.

University of Washington STD Cooperative Research Center, grant number AI-31448; University of Washington/Fred Hutchinson Cancer Research Center's Center for AIDS Research, NIAID grant AI27757.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.