***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Abstract Objective : To determine whether a theoretically based sex education programme for adolescents ( SHARE ) delivered by teachers reduced unsafe sexual intercourse compared with current practice . Design : Cluster r and omised trial with follow up two years after baseline ( six months after intervention ) . A process evaluation investigated the delivery of sex education and broader features of each school . Setting : Twenty five secondary schools in east Scotl and . Participants : 8430 pupils aged 13 - 15 years ; 7616 completed the baseline question naire and 5854 completed the two year follow up question naire . Intervention : SHARE programme ( intervention group ) versus existing sex education ( control programme ) . Main outcome measures : Self reported exposure to sexually transmitted disease , use of condoms and contraceptives at first and most recent sexual intercourse , and unwanted pregnancies . Results : When the intervention group was compared with the conventional sex education group in an intention to treat analysis there were no differences in sexual activity or sexual risk taking by the age of 16 years . However , those in the intervention group reported less regret of first sexual intercourse with most recent partner ( young men 9.9 % difference , 95 % confidence interval −18.7 to −1.0 ; young women 7.7 % difference , −16.6 to 1.2 ) . Pupils evaluated the intervention programme more positively , and their knowledge of sexual health improved . Lack of behavioural effect could not be linked to differential quality of delivery of intervention . Conclusions : Compared with conventional sex education this specially design ed intervention did not reduce sexual risk taking in adolescents PURPOSE To evaluate the effectiveness of peer education when compared to teacher-led curricula in AIDS prevention programs conducted in schools in Rome , Italy . METHODS Eighteen high schools were r and omly assigned to one of two prevention programs : one led by teachers and the other by peer leaders . A sample of students attending the last 2 years ( n = 1295 ) completed pre and post-intervention question naires . Changes in sexual behaviors , knowledge , prevention skills , risk perception and attitudes were first evaluated within each intervention group . Afterwards , changes in knowledge , prevention skills , risk perception , and attitudes total scale scores ( post-test scores minus pre-test scores ) were compared between the two groups , through linear regression models , in order to control for confounders , taking into account the within-school correlation in score changes . As for sexual behaviors , number of sexual partners and frequency of condom use in the 3 months before post-test were compared by intervention group through ordinal regression models , also taking into account behaviors reported before pre-test . RESULTS For both groups , we observed significant improvements in skills , knowledge , attitudes and risk perception . The peer-led group showed a 6.7 % ( 95 % C.I. 1.9 - 11.5 ) scores greater improvement in knowledge , compared to the teacher-led group . In neither group were improvements observed in condom use or number of sexual partners . CONCLUSIONS The only apparent benefit of the peer-led intervention , compared to that led by teachers , was a greater improvement in knowledge of HIV . Neither of the interventions induced changes in sexual behavior . However , the role of possible biases and method ological problems must be considered when interpreting these results Interventions are unlikely to achieve their desired aims unless they are implemented as intended . This paper focuses on factors that impeded or facilitated the implementation of a specially design ed sex education programme , SHARE , which 13 Scottish schools were allocated to deliver in a r and omized trial . Drawing on qualitative and quantitative data provided by teachers , we describe how this intervention was not fully implemented by all teachers or in all schools . Fidelity to the programme was aided by intensive teacher training , compatibility with existing Personal and Social Education ( PSE ) provision , and senior management support . It was hindered by competition for curriculum time , brevity of lessons , low priority accorded to PSE by senior management , particularly in relation to timetabling , and teachers ' limited experience and ability in use of role-play . The nature of the adoption process , staff absence and turnover , theoretical underst and ing of the package , and commitment to the research were also factors influencing the extent of implementation across and within schools . The lessons learned may be useful for those involved in design ing and /or implementing other teacher-delivered school-based health promotion initiatives This paper describes the development of a theoretically based sex education programme currently undergoing a r and omized controlled trial in the UK . It considers some of the practical difficulties involved in translating research -based conclusions into acceptable , replicable and potentially effective classroom lessons . The discussion acknowledges that the implication s of social psychological research and the requirements of rigorous evaluation may conflict with accepted principles inherent in current sex education practice . It also emphasizes that theoretical ideas must be carefully embedded in lessons which are informed by an awareness of classroom culture , and the needs and skills of teachers . For example , the use of same-sex student groups to reflect on the gendered construction of sexuality may be problematic . Material s must be tailored to recipients ' circumstances , which may require substituting for limited experience with the use of detailed scripts and scenarios . Furthermore , role-play techniques for sexual negotiation that work elsewhere may not be effective in the UK . The use of trigger video sessions and other techniques are recommended . Finally , the problems involved in promoting condom-related skills are discussed . The paper concludes that , if an intervention is to be sustainable beyond the research stage , it must be design ed to overcome such problems while remaining theoretically informed A peer-led HIV prevention initiative , based on a diffusion of innovation model , was developed for gay men attending gyms in central London . Peer educators were recruited from people who used the gym regularly according to st and ard selection criteria . After initial training , peer educators agreed to talk to gay men at their gym about HIV prevention , focusing on sexual risk and steroid injecting behaviour . Outcome evaluation revealed that the peer education programme had no significant impact on the risk behaviours of gay men using the gyms . Process evaluation , based on interviews with peer educators , the health promotion team and gym managers threw light on this finding . While it was feasible to set up a peer education programme among gay men in central London gyms , attrition was an important factor . Only one in five potential peer educators initially identified remained with the project throughout , thus limiting the potential for diffusion . Those who did work as peer educators reported barriers to communication within the gyms further limiting the extent to which diffusion occurred . In fact , it appears that the critical mass required for diffusion was never established . This could explain why the intervention had no significant impact on gay men 's risk behaviours . A person-time analysis demonstrated that the peer education programme required a substantial input from the health promotion team , equivalent to one team member devoting 2.5 days a week to recruit , train and support peer educators over 18 months . Peer education should not , therefore , be viewed as a low-cost approach to prevention . Many of the insights gained through this process evaluation can inform others planning peer education programmes in other setting BACKGROUND Improvement of sex education in schools is a key part of the UK government 's strategy to reduce  teenage pregnancy in Engl and . We examined the effectiveness of one form of peer-led sex education in a school-based r and omised trial of over 8000 pupils . METHODS 29 schools were r and omised to either peer-led sex education ( intervention ) or to continue their usual teacher-led sex education ( control ) . In intervention schools , peer educators aged 16 - 17 years delivered three sessions of sex education to 13 - 14 year-old pupils from the same schools . Primary outcome was unprotected ( without condom ) first heterosexual intercourse by age 16 years . Analysis was by intention to treat . FINDINGS By age 16 years , significantly fewer girls reported intercourse in the peer-led arm than in the control arm , but proportions were similar for boys . The proportions of pupils reporting unprotected first sex did not differ for girls ( 8.4 % intervention vs 8.3 % control ) or for boys ( 6.2 % vs 4.7 % ) . Stratified estimates of the difference between arms were -0.4 % ( 95 % CI -3.7 % to 2.8 % , p=0.79 ) for girls and -1.4 % ( -4.4 % to 1.6 % , p=0.36 ) for boys . At follow-up ( mean age 16.0 years [ SD 0.32 ] ) , girls in the intervention arm reported fewer unintended pregnancies , although the difference was borderline ( 2.3 % vs 3.3 % , p=0.07 ) . Girls and boys were more satisfied with peer-led than teacher-led sex education , but 57 % of girls and 32 % of boys wanted sex education in single-sex groups . INTERPRETATION Peer-led sex education was effective in some ways , but broader strategies are needed to improve young people 's  sexual health . The role of single-sex sessions should be investigated further A computer- and Internet-based intervention was design ed to influence several variables related to the prevention of pregnancy , sexually transmitted diseases ( STDs ) , and human immunodeficiency virus ( HIV ) in rural adolescents . The intervention was guided by the extended parallel process model and was evaluated using a pretest – post-test control group design with r and om assignment at the school level . Three hundred and twenty-six tenth- grade males and females enrolled in two rural Appalachian public high schools completed the survey at both points in time . Results indicate the vast majority ( 88.5 % ) of students in the experimental school completed at least one activity ( M = 3.46 for those doing at least one activity ) . Further , both the overall program and all but one of the activities were rated positively by participants . Regarding the effects of the intervention , results indicate that students in the experimental school were less likely to initiate sexual activity and had greater general knowledge , greater condom negotiation self-efficacy , more favorable attitudes toward waiting to have sex , and greater situational self-efficacy than in the control school . In t and em , the results suggest that the computer-based programs may be a cost-effective and easily replicable means of providing teens with basic information and skills necessary to prevent pregnancy , STDs , and HIV This project assessed the impact of a school-based AIDS prevention program on student participation in sexual risk and protective behaviors such as use of condoms and use of condoms with foam and intention to participate in such behaviors . The paper focuses on students who became sexually active for the first time between the seventh and eighth grade ( " changers , " n = 312 ) . The school-based intervention was developed using social cognitive theory and the social influences model of behavior change . Using an experimental , longitudinal design , 15 high-risk school districts were divided r and omly into two treatment ( 10 districts ) and one control ( five districts ) conditions . Students in both treatment conditions received a 10-lesson classroom program in the seventh grade with a five-lesson booster in the eighth grade , while control students received basic AIDS education ( current practice in their districts ) in compliance with state m and ates . Results indicated classroom programs had an impact on certain protective behaviors and on frequency of sexual activity the past month . Post-intervention measures also indicated the program affected students ' intentions to perform specific protective behaviors This r and omized controlled trial tested the effects of a theory-based culture-sensitive HIV risk-reduction intervention among 496 inner-city African American adolescents ( mean age = 13 years ) and examined the generality of its effects as a function of the facilitator 's race and gender and the gender composition of the intervention group . Adolescents who received the HIV risk-reduction intervention expressed more favorable behavioral beliefs about condoms , greater self-efficacy , and stronger condom-use intentions postintervention than did those who received a control intervention on other health issues . Six-month follow-up data collected on 93 % of the adolescents revealed that those who received the HIV risk-reduction intervention reported less HIV risk-associated sexual behavior , including unprotected coitus , than did their counterparts in the control condition . Self-reported sexual behavior and changes in self-reported behavior were unrelated to scores on a st and ard measure of social desirability response bias . There was strong evidence for the generality of intervention effects . Moderator analyses testing eight specific interaction hypotheses and correlational analyses indicated that the effects of the HIV risk-reduction intervention  did not vary as a function of the facilitator 's race or gender , participant 's gender , or the gender composition of the intervention group BACKGROUND The number of reported cases of acquired immune deficiency syndrome ( AIDS ) is increasing disproportionately among Blacks in the United States . The relatively high incidence of sexually transmitted diseases among Black adolescents suggest the need for AIDS prevention programs to reduce their risk of sexually transmitted human immunodeficiency virus ( HIV ) infection . METHODS Black male adolescents ( n = 157 ) were r and omly assigned to receive an AIDS risk reduction intervention aim ed at increasing AIDS-related knowledge and weakening problematic attitudes toward risky sexual behavior , or to receive a control intervention on career opportunities . RESULTS The adolescents who received the AIDS intervention subsequently had greater AIDS knowledge , less favorable attitudes toward risky sexual behavior , and lower intentions to engage in such behavior than did those in the control condition . Follow-up data collected 3 months later revealed that the adolescents who had received the AIDS intervention reported fewer occasions of coitus , fewer coital partners , greater use of condoms , and a lower incidence of heterosexual anal intercourse than did the other adolescents . CONCLUSIONS These results suggest that interventions that increase knowledge about AIDS and change attitudes toward risky sexual behavior may have salutary effects on Black adolescents ' risk of HIV infection This study evaluated the effectiveness of the first year of Safer Choices , a theoretically based , multicomponent HIV , STD , and pregnancy prevention program for high school youth . The study featured a r and omized trial involving 20 schools in California and Texas , with a cohort of 3,869 ninth- grade students . Students who completed both the baseline and the first follow-up survey approximately seven months later were included in the analysis ( n = 3,677 ) . Safer Choices enhanced 9 of 13 psychosocial variables including knowledge , self efficacy for condom use , normative beliefs and 
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Synthesis of the findings of the process evaluations identified a range of factors that might explain outcomes , and these were organized into two overarching categories : the implementation of interventions , and student engagement and intervention acceptability .
Factors which supported implementation and engagement and acceptability included good quality teacher training , involvement and motivation of key school stakeholders and relevance and appeal to young people .
Factors which had a negative impact included teachers ' failure to comprehend the theoretical basis for behaviour change , school logistical problems and omission of topics that young people considered important .