Published online Mar 4. The authors have declared that no competing interests exist. Conceived and designed the experiments: Received May 20; Accepted Jan This article has been cited by other articles in PMC. Abstract Objectives School-based sex education is a cornerstone of HIV prevention for adolescents who continue to bear a disproportionally high HIV burden globally. We systematically reviewed and meta-analyzed the existing evidence for school-based sex education interventions in low- and middle-income countries to determine the efficacy of these interventions in changing HIV-related knowledge and risk behaviors.
We also conducted hand-searching of key journals and secondary reference searching of included articles to identify potential studies. Intervention effects were synthesized through random effects meta-analysis for five outcomes: HIV knowledge, self-efficacy, sexual debut, condom use, and number of sexual partners.
Results Of unique citations initially identified, 64 studies in 63 articles were included in the review. Nine interventions either focused exclusively on abstinence abstinence-only or emphasized abstinence abstinence-plus , whereas the remaining 55 interventions provided comprehensive sex education.
Thirty-three studies were able to be meta-analyzed across five HIV-related outcomes. Results from meta-analysis demonstrate that school-based sex education is an effective strategy for reducing HIV-related risk. Conclusions The paucity of abstinence-only or abstinence-plus interventions identified during the review made comparisons between the predominant comprehensive and less common abstinence-focused programs difficult. Comprehensive school-based sex education interventions adapted from effective programs and those involving a range of school-based and community-based components had the largest impact on changing HIV-related behaviors.
Introduction Worldwide, young people aged 15—24 accounted for almost half of all new HIV infections among individuals aged 15 and older in .
School-based sex education is an intervention that has been promoted to increase HIV-related knowledge and shape safer sexual behaviors to help prevent new infections among this vulnerable group. As sexual debut is common in adolescence, so are the associated risks of engaging in transactional sex, having multiple concurrent partnerships, and experiencing sexual violence and coercion, all of which increase HIV-related risk .
School-based interventions are logistically well-suited to educate youth about sexual activity given their ability to reach large numbers of young people in an environment already equipped to facilitate educational lessons and group learning . Contentious debates have raged in the past decade regarding whether abstinence-only or comprehensive sexual education interventions are effective and appropriate.
Abstinence-only interventions promote delaying sex until marriage with little to no information provided about contraceptives or condom use, whereas comprehensive sexual education provides information on abstinence as well as information on how to engage in safer sex and prevent pregnancies and sexually transmitted infections STIs. Critics of abstinence-only education claim that it violates human rights by withholding potentially life-saving information from people about other means to protect themselves from HIV, such as condom use .
Others argue that abstinence is only a viable option for those who are able to choose when, how, and with whom to have sex, which is not always the case for many young women .
Additionally, promoting abstinence until marriage excludes gay children and adolescents who have no option for marriage in most countries. As an alternative, comprehensive school-based sex education programs present participants with all prevention options, including condom use and partner reduction. Previous research has been conducted on the effectiveness of youth-oriented HIV prevention and sex education interventions in school settings.
A review of 35 school-based sex education programs by Kirby and Coyle  found that abstinence based programs had no significant effect on delaying sexual debut, while some comprehensive programs were effective in reducing certain sexual risk behaviors. Gallant and Maticka-Tyndale  reviewed 11 school-based HIV education programs in Africa and concluded that most studies had an effect on either increasing HIV-related knowledge or changing attitudes or behaviors relating to sexual risk.
However, few reviews have attempted to quantitatively synthesize the effects of school-based interventions on HIV-related risk behaviors across studies, and no review to date has attempted to compare the effectiveness of abstinence-only or abstinence plus interventions with comprehensive sex education in low- and middle-income countries. This review sought to answer the following research question: Does participating in school-based sex education vs.
Methods This review is part of a large systematic review and meta-analysis project, called The Evidence Project, which is a joint collaboration between investigators at the Medical University of South Carolina and the Johns Hopkins Bloomberg School of Public Health. The Evidence Project reviews the efficacy of behavioral HIV prevention interventions in low- and middle-income countries.
Other reviews published with this project include topics such as voluntary counseling and testing  ,  , provider-initiated testing and counseling  , condom social marketing  , behavioral interventions for people living with HIV  , peer education  , psychosocial support  , mass media  , and treatment as prevention . This review used standardized data abstraction forms and procedures that have been employed in all reviews published as part of The Evidence Project, although no standalone protocol has been published specifically for this review.
Definition and Inclusion Criteria School-based sex education was defined as programs designed to encourage sexual risk reduction strategies for HIV prevention delivered in school settings.
This definition allowed for the inclusion of abstinence-only, abstinence-plus, and comprehensive sex education programs. Studies included in the review had to meet the following criteria: There were no restrictions on language; eligible non-English articles were translated by consultants fluent in English and the language in which the article was written. Participant age was also not restricted. Therefore, studies across a variety of educational settings, from primary schools through college and vocational schools, were included.
Additionally, in order to include as many studies as possible, a wide range of study designs were eligible for inclusion: Search strategy Our search strategy involved three methods. The search was limited to a date range of January 1, to June 16, Finally, we searched the reference lists of all included studies for additional eligible studies. This process was iterative and continued until no additional studies were identified.
Trained research assistants conducted an initial screening of all citations and excluded studies clearly not relevant to school-based sex education. Two senior study staff members then independently screened all remaining citations and categorized studies as eligible for inclusion, not eligible for inclusion, or questionable. Discrepancies in categorization were resolved through consensus. Full article texts were obtained and discussed by senior researchers to ascertain eligibility if questionable.
Articles were retained and included as background studies if they failed to meet the inclusion criteria but still contained information relevant to school-based sex education in low- and middle-income countries, including prior reviews, cost-effectiveness analyses, and qualitative studies.
Data Abstraction The following data were abstracted from each eligible study using standardized forms: Two trained research assistants independently abstracted data from each study; any discrepancies were resolved through consensus.
Data were double entered into EpiData version 3. We also evaluated the methodological rigor of studies to assess risk of bias based on the following criteria: Selection of outcomes Outcomes were chosen for meta-analysis based on relevance to HIV prevention and frequency in available studies.
The five most commonly reported outcomes across studies were: All outcomes were based on self-report. Studies containing at least one of these outcomes were included in meta-analysis if they met the following criteria: Provided an estimate of effect size and its variance, or provided statistics needed to calculate an effect size and variance.
If enough information was not provided to calculate an effect size, study authors were contacted for clarification or additional statistics. If study authors did not provide this information after one month, the study was removed from the analysis.
Presented pre-post or multi-arm results comparing either participants who received the intervention to those who did not, or comparing outcomes before and after the intervention. If results of a repeated measures analysis were reported, authors needed to provide the correlation between pre-post measurements or provide enough information to calculate the correlation between measurements.
If these statistics were not available, either in publication or after request, and the study was a controlled design, an effect size was generated using post-intervention statistics provided groups were similar at baseline with respect to the outcome of interest and other relevant covariates.
Presented an outcome of interest that was measured in such a way as to be comparable to outcomes assessed by other studies. In other words, outcomes needed to be similar enough to synthesize across studies. Presented data based on an individual unit of analysis studies presenting classroom- or school-level data only were excluded from meta-analysis.
Meta-analysis Using standard meta-analytic methods  , we standardized effect sizes as either Hedges' g for continuous outcomes or odds ratios for dichotomous outcomes. For several outcomes, including HIV knowledge, self-efficacy, and number of sexual partners, both continuous and dichotomous effect sizes were combined in meta-analysis. In these instances, Comprehensive Meta-Analysis CMA was used to either convert the standard mean difference into an odds ratio when transforming the effect size from continuous to dichotomous or vice versa using methods developed by Hasselblad and Hedges .
This transformation assumes that the outcome under study involves an underlying continuous trait with a logistic distribution  and that outcomes are measured in relatively similar terms, regardless of whether they are presented dichotomously or continuously. For example, several studies reported number of sexual partners as a dichotomous outcome, such as having two or more partners in the past 6 months, whereas others reported a mean number of partners.
Combining both dichotomous and continuous effect sizes allowed us to utilize all available data. Random effects models were used as included studies contained considerable heterogeneity of effects, and the purpose of the analysis was to generate inferences beyond the set of included studies .
When possible, data were analyzed in several ways per outcome. Stratifications by age, gender, instructor e. Additionally, when possible, we investigated the role of certain characteristics of the data itself, including comparing differences between continuous and dichotomous effect sizes and whether the effect size was based on data collected pre-post intervention or post-only.
Mixed effects meta-regression techniques were used to compare effect sizes across strata when possible. The I2 statistic and its confidence interval were calculated for each meta-analysis to describe inconsistencies in effect sizes across studies  , .
When possible adjusted effect sizes were used in the pooled analyses; however, outcomes were most frequently reported in unadjusted terms, thus the analyses contain both adjusted and unadjusted effect sizes. Potential bias across studies, such as publication bias and selective reporting, was assessed for the HIV-related knowledge outcome by constructing a funnel plot.
Funnel plots were not constructed for the remaining meta-analyses because there were too few studies to interpret the dispersion of effect sizes across the range of standard errors. Results Description of studies Of studies initially identified, 64 studies in 63 articles met the inclusion criteria for this review Figure 1. In five cases, more than one article presented data from the same study  — . If articles from the same study presented different outcomes or follow-up times, both articles were retained and included in the review as one study  ,  ,  , .
If both articles presented similar data, such as by providing an update with longer follow-up, the most recent article or the article with the largest sample size was chosen for inclusion  ,  ,  , .