Long-term Effects of a Middle School– and High School–Based Human Immunodeficiency Virus Sexual Risk Prevention Intervention | Adolescent Medicine | JAMA Pediatrics | JAMA Network
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October 2001

Long-term Effects of a Middle School– and High School–Based Human Immunodeficiency Virus Sexual Risk Prevention Intervention

Author Affiliations

From the Department of Pediatrics (Drs Siegel and Aten) and the School of Nursing (Dr Aten), University of Rochester, and the Department of Pediatrics, Rochester General Hospital (Dr Siegel and Ms Enaharo), Rochester, NY.

Arch Pediatr Adolesc Med. 2001;155(10):1117-1126. doi:10.1001/archpedi.155.10.1117

Objective  To determine the longer-term effect (mean ± SD, 41.2 ± 15.3 weeks; range, 14.1-80.5 weeks) of a middle school (MS)– and high school (HS)–based human immunodeficiency virus and sexuality intervention (Rochester AIDS Prevention Project for Youth [RAPP]) on knowledge, self-efficacy, behavior intention, and behaviors.

Design  Quasi-experimental design with 3 intervention groups and 1 control group.

Setting  Urban, predominantly ethnic, minority MS and HS health classes.

Participants  Middle school and HS students (N = 4001) enrolled in health classes in 10 schools. Fifty percent were African American; 16%, Hispanic; 20%, white; and 14%, other. Less than 10% of the students refused participation.

Interventions  There were 4 study conditions: (1) control, usual health education curriculum taught by a classroom teacher; (2) RAPP adult health educator, intervention curriculum implemented by highly trained health educators; (3) RAPP peer educator, intervention implemented by extensively trained HS students; and (4) a comparison of the RAPP intervention curriculum taught by regular health teachers, implemented with MS students only.

Main Outcome Measure  A confidential questionnaire was administered to all study subjects before and at long-term follow-up after the intervention, containing scales to measure knowledge, self-efficacy, behavior intention, and behaviors, including onset of sexual intercourse experience and engagement in risky sexual behaviors.

Results  Rates of baseline sexual activity in the sample were comparable to those found in other urban school-based surveys. Long-term knowledge (MS females, P<.001; and MS males, P<.01) and sexual self-efficacy (MS females, P<.05; and HS females, P<.01) scores were higher among the intervention groups (male and female are used in this study to describe those aged 9½-23 years). Intention to remain safe regarding sexual behavior was also greater among intervention groups in MS but not HS. However, subjects who were already sexually active at pretest were less likely to show a positive intervention effect. An intervention effect for the onset of intercourse and risky sexual behavior was found most significantly among MS females.

Conclusions  A positive long-term effect from the RAPP intervention was observed, particularly for youth who were involved in less risk (eg, not yet sexually active) at study enrollment. Thus, we propose that the most appropriate time for intervention implementation is earlier in adolescence, before the onset of risky behaviors.

DESPITE MANY efforts directed at prevention, adolescents continue to represent a significant proportion of Americans who are diagnosed as having sexually transmitted diseases.1,2 In addition, unintended pregnancy among US teenagers persists and carries medical, emotional, and social costs.3,4 Although only a few of those in the United States with the acquired immunodeficiency syndrome (AIDS) are adolescents,5 given the long incubation period for the human immunodeficiency virus (HIV), it is estimated that one fifth of those with AIDS were infected as teenagers.6 Since neither a cure nor an effective vaccination has yet been developed, primary prevention remains the most powerful strategy for curbing this epidemic. Since behaviors determine the likelihood of HIV infection, prevention programs must focus on maintaining safer behaviors (such as abstinence from sexual intercourse or consistent use of condoms and other barriers)7,8 and interventions need to include many participants to effectively reduce HIV risk in an adolescent population.

In an effort to capture large groups of teenagers for developing effective HIV, sexually transmitted disease, and pregnancy prevention interventions, research9-12 has been based in urban schools, where reported rates of having already experienced sexual intercourse are relatively high. Because schools are structured to gather students as a "captive audience," and some form of HIV and family life education is already part of the curriculum, it is an ideal setting for implementing and testing HIV and sexual risk prevention interventions. In an earlier publication,12 the short-term results of the Rochester AIDS Prevention Project for Youth (RAPP) were presented. The intervention was successful in increasing not only knowledge but also intentions to behave in sexually safer ways. The RAPP intervention, taught by peer educators (Peer Eds) and, in middle school (MS), by regular health teachers (RHTs), demonstrated a positive effect relative to the control and the health educator (H Ed)–taught groups. Meaningful behavior change outcomes from the RAPP intervention can only be described after sufficient follow-up. Little published work in this area reports on follow-up beyond 3 to 6 months.10 The present report describes the longer-term (mean ± SD follow-up, 41.2 ± 15.3 weeks) effect of RAPP on knowledge, self-efficacy, behavior intentions, and, most important, behaviors related to sexual intercourse and risk for HIV infection.

Participants and methods


The subjects (N = 4001) (Table 1) were drawn from 10 urban schools in a medium-sized northeastern city with a population of approximately 250 000. The criteria for study inclusion were that students were (1) enrolled in required health education classes and (2) fluent in either English or Spanish. The ethnicity of the sample was diverse: 50% were African American; 16%, Hispanic; 20%, white, non-Hispanic; and 14%, other (including Asians, Native Americans, and those who indicated that they were biracial). Although the student population of the school district is generally of low socioeconomic status (70% of the families have incomes less than the federal poverty level), some differences might have confounded findings. For confidentiality reasons, and because younger teenagers often do not know about family income, employment, or education, we used a socioeconomic status proxy based on median house value, rent, and family income and on educational level of the adult population within each census tract. The proxy (socioeconomic area [SEA]) consisted of subject-reported ZIP code and street address, and the mean SEA was 5.2 (SD, 2.7), slightly lower for MS than high school (HS) students.

Table 1. 
Comparison of RAPP Sample Descriptive Characteristics by Intervention Group Within School Level*
Comparison of RAPP Sample Descriptive Characteristics by Intervention Group Within School Level*



Students were recruited (as classroom cohorts) within their regular school health education classes to participate in RAPP, a quasi-experimental classroom-based intervention designed to increase knowledge and skills aimed at safe behavior regarding sexuality and HIV/AIDS. Passive parental consent for student participation was obtained. The parents of all students scheduled to take health in the upcoming school year are routinely sent a letter from the district director of health and physical education informing them that family life education, including sexuality, will be taught and they can request their son or daughter not participate in that unit. During the study, a description of the RAPP program was a part of this letter, and parents were given the opportunity to inquire further about RAPP and/or refuse participation. Questions were directed to the study principal investigator (D.M.S.), who met with parents individually to address their concerns; few (<10 families) withdrew their son or daughter. The opportunity to refuse study participation was verbally offered in the classroom after the study description and before the first session. In addition, students were told that they could withdraw from the study at any time, and on the study instrument, instructions indicated that a student could choose not to complete the questionnaire.

Classes were assigned within semesters to 1 of 3 conditions: (1) control, the usual health education curriculum taught by the RHT; (2) RAPP adult H Ed, the RAPP intervention implemented by a male-female ethnically diverse pair of highly trained adult educators; or (3) RAPP Peer Ed, volunteer HS students who completed approximately 50 hours of preparation by RAPP staff and taught the RAPP curriculum as pairs of educators. Health education in MS was taught in seventh grade only, while in HS, students had the option to take health in 10th, 11th, or 12th grade; most students chose 10th or 11th grade. The semester assignment of classes to the intervention condition was based on feasibility issues and the availability of Peer Eds. However, by study conclusion, all health classes in each of the participating MSs and HSs had been assigned to each of the study groups (experimental and control). At no time did intervention and control conditions take place in the same school during a given semester. These design features enhanced generalizability by ensuring that the study groups were spread across all different schools, while avoiding contamination between intervention and control classes. Within the year following the main study, regular MS teachers only were trained to implement the curriculum. This fourth study condition tested the transfer of the content and process of teaching to regular school personnel.

The RAPP intervention (H Ed, Peer Ed, or RHT) consisted of 10 (HS) or 12 (MS) consecutive health class sessions (usually 2 or 3 sessions per week) delivered for 2 to 7 weeks. The intervention was integrated into the regular school health education schedule to avoid disruption within schools and to build an intervention that might generalize to other schools in the future. The content was based on literature9 concerning school-based interventions, the expertise of the RAPP H Eds, and principles from the Theory of Reasoned Action13,14 and normal adolescent development. The intervention is most similar to the fourth generation of "abstinence plus" interventions, which promote sexual abstinence but also include safer sex messages.11 Early sessions emphasized self-esteem and decision-making strategies, while later classes progressed through in-depth discussion and skill-based activities concerning sexuality, sexually transmitted diseases, pregnancy, and, finally, HIV/AIDS. This last topic received particular emphasis, and all sessions included small- and large-group activities such as games, role plays, and take-home exercises often requiring parental input. Priority was placed on maximum engagement of the students in a highly interactive and dynamic learning experience in both intervention conditions.

Data Collection

Students completed a confidential survey at baseline (preintervention), immediately after the intervention, and at long-term follow-up. The survey instrument, available in English and Spanish, was read to students during a 40-minute health class by the project H Eds. The study was reviewed and approved by the administration of the local school district and the university institutional research review board. Students were assured that their answers were confidential to the research staff, and that they could participate in the health classes without completing the research instrument. More than 90% of the students completed the survey preintervention. Those who declined participation were provided alternate school activities. Subjects were tracked over time by using (1) a school district–assigned identification (ID) number and (2) an RAPP study ID number. Specifically, each health class teacher maintained a roster of student names and associated school ID numbers. A separate study team list associated the school ID numbers with unique RAPP-assigned subject numbers. Surveys maintained by the study team were only labeled with the subject number, while the school maintained the separate roster that contained the student name and district ID number. This dual-list procedure confirmed that, despite student mobility, duplicate subject enrollment did not occur and student confidentiality was carefully preserved.

Study Instrument

The survey questionnaire, pilot tested on 450 students preceding the main study, measured constructs determined to be important in assessing the impact of the RAPP curriculum and has been described in detail elsewhere.12 Those variables reported herein include demographics, knowledge, self-efficacy regarding sexual matters, behavior intention within the next year, history of risk behaviors, history of sexual experiences, and self-reports of behavior. The variable items and their psychometric properties are summarized in Table 2.

Table 2. 
Study Variables and Scales*
Study Variables and Scales*

Variables measured

In addition to demographics (age, sex, ethnicity, and the SEA proxy for socioeconomic status), scales (summarized in Table 2) were developed during a pilot phase, because of the lack of reliable and valid scales reported in the literature. Existing literature was reviewed to include variables represented in the Theory of Reasoned Action. Reliabilities were computed separately for MS and HS students and ranged from 0.74 to 0.80 (n = 3800 students) for α (internal consistency) and from 0.66 to 0.84 for test-retest reliability (n = 450 students). Factor analyses for each construct revealed 1-factor solutions for all constructs except "involvement in sexual risk behaviors," which supported 3 factors ("somesex" represented the initiation of sexual intercourse, and "risksex" represented some risk involvement). Variance accounted for by the factors ranged from 10% to 36%.


Students responded to the 26 items with yes if they believed the statement to be true; no, if false; and not sure (a choice scored as incorrect and included to minimize guessing and inflation of correct response scores). To avoid a ceiling effect, individual items were included only if they had less than 80% correct responses during the pilot phase.

Sex Self-efficacy

This scale, developed from similar work by Misovich et al,15 asked how hard or easy it would be to carry out each of 8 behaviors in relation to sexuality.

Behavior Intention

An index of intention to behave in safe ways12 included 9 items to indicate student agreement or disagreement on 7-point scales with selected statements concerning sexual behavior and substance use.

Life Risk History

Items from the Youth Risk Behavior Survey16 were used to tap 15 questions concerning school- and community-related risks. Furthermore, we asked a panel of 25 experts in adolescent health (clinicians and behavioral scientists) to rank the level of risk: 0 indicates no or minimal risk (eg, missed school without permission); 1, some risk (eg, tried marijuana); and 2, substantial risk (eg, used marijuana regularly).

History of Sexual Intercourse

Preintervention, students were asked about their history of sexual intercourse as part of 7 different items addressing onset, frequency, and multiple partner experience. The degree to which students were consistent across all 7 items in which there was an opportunity to answer "I have never had sex" was examined to be confident regarding the validity of responses. Particularly for younger students, it was important that subjects understood the concept of sexual intercourse before initiating the intervention. Students were categorized as ever having had sexual intercourse (score of 1) or never having had sexual intercourse (score of 0).

Involvement in Sexual Risk Behaviors

To assess involvement in sexual behavior, students were queried as to their initiation and engagement in 13 selected behaviors. Factor analyses resulted in 3 dimensions: (1) somesex or the initiation and onset of sexual intercourse experience, which included 5 items (ever carry condoms, ever had sexual intercourse, communication with a partner about sex, have had sex 1-5 times within the past 3 months, and planning ahead to have sex), representing 33% of the variance; (2) risksex or the engagement in some risky behaviors, which included 5 items (tried to get pregnant or get a partner pregnant, actual pregnancy involvement, having had sex when the teenager really did not want to, having sex while using alcohol or other drugs, and having had sex >5 times in the past 3 months), representing 10% of the variance; and (3) engagement in high-risk sexual behaviors (history of sex with an intravenous drug user, anal sex, oral sex, and a history of HIV testing), representing 8% of the variance. The third dimension was not meaningful to further analyses as there were few students who engaged in these most serious behaviors. The first 2 factors were used as dependent variables in analyses of whether and how much engagement in actual sexual behavior was reported at longer-term follow-up for all intervention groups.

Class climate

To test for any differences across various learning settings, the existing health education class environment was observed and scored by the adult RAPP educators for all participating teachers/classrooms. Working independently, each member of a pair of RAPP H Eds rated the physical environment and the classroom health teacher's facilitation of the RAPP curriculum. The 18 items were summed to form an overall "class climate" score (range, 0-36). Rater agreement was high (r>0.80), and the 2 scores were averaged.

Data analyses

Since the study design was a quasi experiment, it was important to consider whether there were preintervention differences in study variables that might confound findings in relation to long-term outcomes. Therefore, demographics (age, sex, SEA, and ethnicity), the proportions of females and males (female and male are used in this study to describe those aged 9½-23 years) who reported sexual intercourse experience, and the study variables of interest (knowledge, sexual self-efficacy, general life risk, sex safe behavior intention, and the self-reports of behaviors concerning initiation of sexual behavior and involvement in risky sexual behavior) were compared within the MS and HS groups and by sex. Previous work17,18 has documented differences in sexual behavior by age and sex (eg, earlier sexual debut in males vs females). Also, we compared the observation rating for the class climate score among the MS and HS groups. Then, the major study analyses concerning long-term outcomes were tested by repeated-measures analyses of variance.

The study was a 3-factor design (4 by 2 by 4); the factors were ethnicity (African American, Hispanic, non-Hispanic white, and other), history of sexual intercourse experience (yes or no), and intervention group (control, H Ed–taught, Peer Ed–taught, and, in MS, RHT-taught students). The procedure for analyses was that demographics, the general life risk score, the mean score for length of time from intervention, the class climate score, and the relevant pretest score for each dependent variable were entered as covariates. Then, each of the factors was entered with the intervention factor considered last. The strategy was to delineate the long-term intervention effect beyond other related variables. The interaction between sexual activity status and intervention group was also examined to determine a given intervention's differential effectiveness based on whether subjects were sexually active. Since the sample was large and statistical significance is easily reached with large sample sizes, effect sizes (η values) are reported for the intervention, as is the total variance accounted for by the model (R2).


The mean ± SD duration of long-term follow-up in this study was 41.2 ± 15.3 weeks (range, 14.1-80.5 weeks); overall, two thirds of the subjects were present at study conclusion (72% in MS and 55% in HS). Among 12th graders, 73% did not complete long-term follow-up because of graduation or drop out, while the attrition for 10th and 11th grade was 55% and 43%, respectively. The 4 intervention groups among the MSs (control, H Ed, Peer Ed, and RHT) and the 3 groups among the HSs (control, H Ed, and Peer Ed) were compared to determine whether there were significant differences in demographic variables (Table 1) and for the study variables of interest. While there were significant differences for age, SEA, ethnicity, and the proportions of students who reported a history of sexual intercourse experience preintervention, the magnitude of the differences was, for the most part, small. The most important differences were that, for MS students, the proportion of females who reported having experienced intercourse preintervention ranged from 18.4% for RHT-taught students to 34.2% for H Ed–taught students. In contrast, many more males among the MS sample reported sexual experience preintervention, ranging from 53.2% of RHT-taught students to 66.2% of Peer Ed–taught students. Overall, in MS, about 30% of females and 63% of males reported sexual experience at baseline. Among the HS students, the range of sexual experience among females was from 60.6% of Peer Ed–taught students to 73.2% of the controls, while the range among males was from 69.3% of Peer Ed–taught students to 82.3% of controls. Demographics and the self-reported history of sexual intercourse experience were entered as covariates in all analyses.

Pretest scores for the major study variables were also used as covariates in analyses of long-term intervention effects since there were slight preintervention differences across study groups. It was also important to control for each subject's pretest score before assessing the intervention effect. Most differences, however, while statistically significant, did not indicate meaningful distinctions. For example, MS sexual self-efficacy scores were higher (safer) among H Ed–taught students (37.5), Peer Ed–taught students (37.5), and RHT-taught students (37.9) compared with control students (35.7) (P<.001). Classroom climate scores represented the greatest preintervention differences between control and intervention groups, with the largest discrepancy between MS control (22.5) and RHT (29.9) groups (P<.001) on a scale that ranged from 12 to 31.

Table 3, Table 4, Table 5, and Table 6 present the analyses of variance models conducted for each of the dependent variables. The format of these tables is the same as that used in an earlier article.12 Using Table 3 as an example, the data presentation is as follows. Subjects were stratified by school level and sex, with variables sequentially entered into the analysis of variance, shown in the table as rows. In Table 3 (predicting knowledge at posttest), for MS females, the collective contribution of the covariates to the model yielded an F value of 14.7, with a significance of P<.001. Taking the covariates separately, age was a meaningful predictor, with an F value of 11.4, as was SEA, with an F value of 24.9.

Table 3. 
Prediction of Long-term Postintervention Knowledge Scores Among Middle and High School Students (ANOVA)*
Prediction of Long-term Postintervention Knowledge Scores Among Middle and High School Students (ANOVA)*
Table 4. 
Prediction of Long-term Postintervention Self-efficacy Scores Among Middle and High School Students (ANOVA)*
Prediction of Long-term Postintervention Self-efficacy Scores Among Middle and High School Students (ANOVA)*
Table 5. 
Prediction of Long-term Postintervention Safe Behavior Intention Scores Among Middle and High School Students (ANOVA)*
Prediction of Long-term Postintervention Safe Behavior Intention Scores Among Middle and High School Students (ANOVA)*
Table 6. 
Prediction of Long-term "Somesex" Scores Among Middle and High School Students (ANOVA)*
Prediction of Long-term "Somesex" Scores Among Middle and High School Students (ANOVA)*

Also in Table 3, for MS females, the combined contribution of all main effects (to the posttest knowledge score) was significant, with an F value of 12.2, while ethnicity alone accounted for an F value of 10.1. In the lower half of the table, the mean score from the study instrument for the dependent variable in question is provided. In Table 3, this would be the mean knowledge scale score. For example, among the MS females, the F value for the contribution of intervention group membership to knowledge score at posttest was 20.3, and the mean knowledge scale score for the control group was 12.9 compared with 15.6, 15.9, and 15.5 for the H Ed, Peer Ed, and RHT groups, respectively.

For long-term knowledge (Table 3), covariates were important contributors to outcomes. Increasing age, a higher SEA, a better class climate score, time from intervention (except HS males), and the pretest knowledge score (except HS males) were significant. The long-term knowledge means were consistently greater for the intervention groups compared with the controls, and were significant for MS females and males. There were some ethnic differences; white non-Hispanic students generally had higher knowledge scores, followed by African Americans and Hispanics. The means for self-efficacy (Table 4) were higher for each of the intervention groups compared with the controls, reaching significance for the MS and HS females. Ethnic differences were noted in that Hispanic youth generally reported less self-efficacy than did other groups. Covariate significance was almost entirely accounted for by the pretest self-efficacy score and was highly significant (F values ranged from 80.0 to 175.0). There were no differences for either knowledge or self-efficacy in relation to whether there was a history of sexual intercourse. Long-term η values ranged from 0.17 to 0.29 for knowledge and from 0.11 to 0.15 for self-efficacy. The proportions of variance explained by the models (R2) ranged from 0.11 to 0.27 for knowledge and from 0.12 to 0.35 for self-efficacy, with more variance explained in the HS models.

Intention to remain safe in regard to sexual behavior was the third variable considered for short-term outcomes,12 and tested again for longer-term outcome in the present analyses (Table 5). Among MS students, the means were lower (representing less intention to remain safe, including remaining abstinent) for the controls than the intervention groups. There was no intervention effect for HS students, likely reflecting the high prevalence of sexual experience that preceded the intervention. In all groups, the pretest score for intention was again the most significant and powerful covariate (F values ranged from 98.2 to 223.7). Other covariates, especially the general life risk score (F values ranged from 9.9 to 37.6), were also significant. Unlike knowledge and self-efficacy, the means for intention to be safe were lower for those students who reported a history of sexual experience preintervention, especially for the MS males (P<.01). The η values ranged from 0.11 to 0.26, and the R2 for the model ranged from 0.26 to 0.54; greater variance was explained among HS students.

Finally, we examined the long-term intervention effect for the index scores described (in the "Variables Measured" subsection of the "Participants and Methods" section), which represented initiation of sexual activity (somesex [Table 6]) and engagement in more risky sexual behavior (risksex). For somesex, with the exception of HS females, the means were in the expected direction for an intervention effect, ie, the higher means (representing less involvement in sexual exploration) were found for the intervention groups compared with the controls. Significance, however, was reached only among the MS females, likely because this group reported the least (30%) history of sexual experience preintervention. There was also a significant interaction effect for sex history by intervention for Peer Ed–taught males at the HS level. The pretest covariate for somesex was highly significant (F values ranged from 207.4 to 320.9), and the history of sexual experience was also significantly related to long-term sexual behavior (F values ranged from 30.3 to 45.4), with higher (safer) scores among those not yet sexually active. Furthermore, the general life risk covariate was also significant for all groups, suggesting that preintervention risk (whether sexual or nonsexual) was significant in predicting later sexual behavior. In relation to ethnicity, African American youth had lower mean scores for this variable, indicating that they reported greater engagement in sexual activity. The η values were small (0.06-0.17), and the R2 values for the models ranged from 0.40 to 0.54.

Prediction of engagement in risky sex behavior (risksex) was more difficult; significance for the intervention was not demonstrated, as most students did not report these behaviors. However, the means were in the expected direction for the intervention groups, with the controls having slightly lower mean scores (representing less safety) than the intervention groups among all students. There was a statistically significant interaction for sex activity status by intervention for MS females, indicating that sexually active (vs nonsexually active) females were more positively affected by the intervention (P<.001). Analogous to the other analyses, increasing age, greater life risk, a history of sexual experience preintervention, and especially the pretest score for risky behavior (F values ranged from 44 to 223) were highly significant. The degree of variance explained by each of the 4 models for risksex ranged from an R2 of 0.17 to an R2 of 0.43.


Numerous efforts to reduce behavioral risk (especially sexual risk) have examined short-term change, while fewer studies follow up subjects beyond 6 months. Findings describing 12-month after the intervention follow-up in school-based studies are unusual.10,19 The η values for interventions are most often larger for nonbehavioral outcomes (such as knowledge) and frequently lessen over time.19,20 The sample in this report, by virtue of the available school population, included students at serious sexual risk and those youngsters who were at potentially no risk for early life entry into sexual risk. Longer-term behavior η values are usually small in such studies,19,21 and in many instances have not been considered at all. Our long-term η values ranged from a medium effect of 0.25 (knowledge) to smaller behavior η values of 0.14 (somesex) and 0.13 (risksex), findings that are consistent with other adolescent sex risk reduction studies and with behavior studies aimed at risk reduction in other domains.

There was a positive, sustained, long-term effect of the RAPP intervention when compared with the control intervention in the areas of knowledge, self-efficacy regarding sexual matters, behavior intention, and self-reported behaviors. While statistical significance was not universally reached, when compared with control across intervention groups, mean scores were consistently in the desired safer direction. This was especially true for the Peer Ed– and (at MS) the RHT-taught groups. Since students' pretest variable score heavily influenced their score on that same variable at follow-up, this observation speaks to the need for development and testing of school-based sexual risk reduction interventions among younger students, such as those in the late elementary grades. In a preliminary analysis of our data (not presented herein), we had not initially included sexual history as a covariate and found that there was more significant effect of the intervention compared with the control. When sexual history was entered into the analysis of variance before examining for the intervention effect, the impact of the latter was diminished. This is consistent with the association of a more positive outcome in the presence of "safer" pretest scores, because the initiation of sexual intercourse is included as a contributing item to the somesex and risksex indexes.

Interpretations of school-based intervention trials such as RAPP are bolstered by the inclusion of many subjects who are representative of a general adolescent population. The prospects of implementing programs found to be successful are also brighter compared with community-based efforts since school structures already exist in every community and are, in fact, obligated to provide curriculum time related to family values and sexuality. At the same time, there are limitations to be considered in evaluating RAPP. The quasi-experimental design we used was necessary to carry out a large school-based study that would not disrupt the usual class and grade structure to such an extent that the project would have been rejected by the participating institutions. This resulted, however, in lack of true subject randomization. Our analyses for group differences in baseline characteristics revealed statistical significance across several variables, but the magnitude of scale score differences was not clinically meaningful, and the relevant variables were entered in the analysis of variance to further control for their potential effect on the dependent variable. In addition, not all subjects who enrolled in the study were present at longest follow-up. Such attrition, greater in HS and particularly among 12th graders, presents potential bias in results. We examined relevant pretest characteristics of those students who did and did not participate in late follow-up, and there was a slight overrepresentation of higher-risk (related to sexual behavior) students among study dropouts. Their inclusion at follow-up might have diminished the observed intervention effect, but again we expected and found that the most intervention-responsive students were those who were yet to engage in risk behaviors.

Another reality of this type of work is that the most meaningful outcome, behavior, is measured by self-report. With this potential source of error in mind, we asked subjects about sexual experience in multiple ways (see the "Variables Measured" subsection of the "Participants and Methods" section) and assessed their behavior only based on consistent responses. Thus, we believe our index of sexual activity is accurate. This and the other measures for the study were pilot tested at MS and HS levels, and the instrument was not finalized until reliability and validity were addressed.

It is clear that the goal for school-based interventions of this type should be the primary prevention of risky sexual behavior. Since this can only occur in younger, precoital populations, we propose that late elementary school students, before the transition to sexual activity, should be the target group for the next phase of study.

Accepted for publication April 10, 2001.

This study was supported by grant 49037 from the National Institute of Mental Health, Rockville, Md.

We thank Barbara Thompson for her tireless preparation of the manuscript; the staff of the Rochester AIDS Prevention Project for Youth, including the health educators (Margaret Cain, BA; Raúl Corujo-Molina; Desiree Voorhies, RN, MSEd; and Lennard Wedderburn, CSW) and the research assistant (Terri Vaughn, CSW), for their dedication, commitment, and hard work on behalf of the project; and the staff and students of the participating schools.

What This Study Adds

A significant proportion of young adults with AIDS became infected with HIV through sexual contact during adolescence. A prior report showed that a school-based intervention was successful in the short-term in improving knowledge and changing behavior.

This study found that at an average of 10½ months after the intervention, MS and HS students still demonstrated a positive effect of the program on several important measures related to safe sex. Intensively trained HS Peer Eds can function as effective implementers of an HIV sexual risk prevention program.

Corresponding author and reprints: David M. Siegel, MD, MPH, Department of Pediatrics, Rochester General Hospital, 1425 Portland Ave, Rochester, NY 14621 (e-mail: david_siegel@urmc.rochester.edu).

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