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HIV/AIDS, other STIs and Teen Pregnancy: Group-Based Abstinence Education Interventions for Adolescents


What the Task Force Found

About The Systematic Review

The Task Force finding is based on evidence from a systematic review of 21 studies with 23 study arms (search period 1988 - August 2007). The systematic review was conducted on behalf of the Task Force by a team of specialists in systematic review methods, and in research, practice, and policy related to preventing HIV/AIDS, other STIs, and teen pregnancy.


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Summary of Results

Twenty-one studies with 23 study arms qualified for analysis in this review. The meta-analyses found the following results for primary outcomes:

  • Sexual activity: decrease of approximately 16% (odds ratio [OR]=0.81, 95% confidence interval [CI] 0.70, 0.94; 21 study arms)
    • This decrease is statistically significant, however, effect estimates differed by study design with larger effects for nonrandomized controlled trials compared to randomized controlled trials.
    • Studies with both designs had problems such as differences in follow-up time and multiple studies conducted by the same investigators.
  • Frequency of sex OR=0.77, 95% CI 0.57, 1.04 ( 5 study arms)
    • This result, although in the favorable direction (decrease in frequency), is statistically nonsignificant. Also, effect estimates differed by study design with larger effects for nonrandomized controlled trials compared to randomized controlled trials.
  • STIs: increase of approximately 8% that was statistically nonsignificant (OR=1.08, 95% CI 0.90, 1.29; 9 study arms)
  • Pregnancy: increase of approximately 12% (OR=1.15, 1.00, 1.32; 10 study arms)
    • Although this increase is statistically significant, sensitivity analyses suggest that the effect estimate is unreliable.
  • AE had no meaningful effect on any of the following secondary outcomes:
    • Number of sexual partners
    • Use of protection
    • Unprotected sexual activity
  • In two of the studies, at least one relevant outcome was reported that could not be included in the meta-analysis because of too little information to calculate an odds ratio. The results for these studies were consistent with the results of the meta-analysis.

Summary of Economic Evidence

An economic review of this intervention was not conducted because the Task Force did not have enough information to determine if the intervention works.


Applicability of this intervention across different settings and populations was not assessed because the Task Force did not have enough information to determine if the intervention works.

Evidence Gaps

Each Community Preventive Services Task Force (Task Force) review identifies critical evidence gaps—areas where information is lacking. Evidence gaps can exist whether or not a recommendation is made. In cases when the Task Force finds insufficient evidence to determine whether an intervention strategy works, evidence gaps encourage researchers and program evaluators to conduct more effectiveness studies. When the Task Force recommends an intervention, evidence gaps highlight missing information that would help users determine if the intervention could meet their particular needs. For example, evidence may be needed to determine where the intervention will work, with which populations, how much it will cost to implement, whether it will provide adequate return on investment, or how users should structure or deliver the intervention to ensure effectiveness. Finally, evidence may be missing for outcomes different from those on which the Task Force recommendation is based.

Identified Evidence Gaps

The following outlines evidence gaps for these group-based behavioral interventions to prevent or reduce the risk of adolescent pregnancy, HIV/AIDS, or other STIs: comprehensive risk reduction, and abstinence education interventions.

Across both reviews, there was no consistent evidence of differential effects on outcomes for any of the 12 critical moderator variables (gender, virginity status, age, race/ethnicity, setting, dosage, focus, deliverer, multicomponent, targeting, study design, and comparison group type). Also, the majority of the studies examined interventions delivered to coed groups and results were not reported by gender. This limits the ability to determine differential effectiveness by gender for comprehensive risk-reduction and abstinence education interventions. This limitation extends to the evaluation of the effectiveness of parental participation as well, since it was an uncommon component in these reviews and often had low participation rates.

More consistent reporting of moderator variables by study authors is needed to clarify which of these (or other characteristics) may maximize the effectiveness of adolescent sexual behavior interventions. In addition, common measures of sexual behavior and standard intervals for follow-up assessments of these outcomes would allow for more comparability across studies and lead to a better determination of the overall public health impact of these interventions.

In terms of economic efficiency, future research is needed to examine how cost– benefit or cost-effectiveness estimates vary depending on age, gender, and risk status of participants. For programs with objectives beyond pregnancy and STI prevention, future research needs to evaluate the full impact of such programs from a societal perspective, including non-health outcomes such as improved employment potential, and higher future earnings of program participants. Finally, for school-based programs, additional research needs to address the impact on school resources where the facilities, staff, or time from the school systems may be used for these programs.

Study Characteristics

Interventions included in this review were:

  • Targeted to adolescents
    • Girls only
    • Boys only
    • Girls and boys together
  • Delivered in group settings in schools or communities
  • Led by adult or peer educators
  • Implemented as single or multicomponent programs
  • Tailored to groups or individuals

Content of these interventions addressed prevention of:

  • HIV and STIs
  • Pregnancy