Well‐designed intervention studies can provide invaluable evidence about how different interventions may impact on condom use in different settings, and in different forms of sexual partnership. It was hoped that, by focusing on peer‐reviewed publications, the quality of studies reviewed would be assured, although in practice, the quality of the evidence varied widely. Only six of the 42 studies presented in table 2 were RCTs,27,29,40,47,51,78
and two others randomised communities to intervention or control conditions69,82
. Unfortunately, four of the RCTs29,40,51,69
and four of the NRCTs31,32,73,79
presented only pre–post comparisons rather than significance testing of the male condom intervention group versus the control group at follow‐up. Otherwise, most studies did not include a control group, or did not randomly allocate to intervention and control groups, which may limit the reliability of conclusions about intervention effect. For the studies with no comparison group, some of the observed increases in condom use may also reflect underlying temporal effects, in addition to intervention effects.9,10
The focus on published reports may have also led to a publication bias towards studies showing impact.
Fundamentally, the conclusions from the review will be limited by the degree to which condom use is accurately reported. There may be inaccuracies from reporting bias due to social desirability compelling participants to over‐report condom use, since they are part of a project in which condoms are promoted, or to under‐report condom use if condoms are stigmatised in the population.89
Some studies attempted to validate self‐reported sexual behaviour data through the inclusion of biological endpoints.26,28,33,40,41,69,71,76,77,80
The majority of these reported significant declines in the prevalence/incidence of HIV26,28,71
or other STIs,26,28,33,71,76,80
while one found only minor differences in STI prevalence between consistent and inconsistent users,40
and another had baseline rates of STIs that were too low to demonstrate any change.69
Significant increases in HIV/STI prevalence were reported in two of the studies,41,77
with the authors of one suggesting that a history of condom use was likely to be a marker for more frequent commercial sex,77
and the other concluding that the findings emphasise the need for a broad range of interventions alongside political and social engagement.41
When considering this evidence, it is important to keep in mind that condom effectiveness against an STI depends on the infectivity of that specific STI.90
Other methods of validation included asking both male and female partners about their condom use,37,80
or comparing the reported coital frequency and condom use data with the number of condoms distributed.40
Although UNAIDS and other agencies have invested in methodological research to identify how best to enquire about condom use,89
several imprecise measures were used in the studies reviewed. It may be that increased use at last sex reflects greater uptake of condoms by non‐users, while increased consistency of use may reflect increased use by existing users. The lack of standardised measures of condom use meant that summary measures of impact could not be developed. As over a quarter of the studies examined combined partnership types, there were also limitations about the degree to which intervention impact on condom use in different forms of relationship could be assessed. Those studies that did specify the partnership type were grouped accordingly, despite the heterogeneity of the studies in each group, which varied by target population, intervention type, geographic area and baseline levels of condom use. Had more studies met the inclusion criteria, these could have perhaps formed more homogenous sub‐groups for comparison within each partnership type.
Despite these limitations, this review provides an overview of current evidence. There is substantial evidence of interventions targeted at sex workers and their clients, in both African and Asian contexts, achieving significant large increases in condom use. These interventions seem to primarily utilise peer or other health education combined with STI testing and treatment. Further research is needed to disentangle the factors influential on the largest gains in condom usage.
There is far less evidence about intervention impact on levels of condom use in casual sexual relationships. This lack of evidence makes it impossible to draw any conclusions and highlights the need for further evaluation studies in this area, particularly since, in many parts of the world, casual sex is a potentially important mechanism for HIV transmission.
In primary partnerships, postintervention condom use was generally low unless one partner was knowingly HIV‐infected or at high risk, or avoiding pregnancy. The evidence suggests that increased condom use among primary partnerships is most feasible if the perception of risk of an unwanted outcome (ie, HIV/STI infection or pregnancy) is high, although the stigma of HIV may also influence behaviour. More studies of condom use in long‐term partnerships following interventions targeted at low‐risk groups are required.
There was mixed evidence of the impact of condom promotion among youth. Compared with other target populations, interventions among youths recorded a lower increase in condom use. However, high levels of use are possible. Geographically the evidence is skewed, as only one study focused on Asia. The lack of data highlights the need for further evaluations of interventions for youths, particularly in Asia. Such interventions should draw upon a recent review conducted by WHO, identifying the forms of intervention for adolescents that are most promising.21
Promoting condoms for contraception may increase use among young people, as Cleland and Ali (2006) found that, across 13 African countries, pregnancy prevention can be an important motivating force for condom use by young single women.9
Gender differences were also noted. In five of the articles included in the review, condom use increased significantly among males but not females within the same study,30,31,43,44,49
while only one study found the reverse among youths.47
This highlights that condom use depends on male cooperation.