***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: The effectiveness of an intervention based upon the theories of Ajzen and Tri and is was evaluated among 698 junior and 306 senior high school students . The intervention to juniors was offered by  senior students who were trained during a course integrated into the school curriculum . Respondents in the control and experimental groups completed a question naire at baseline and 9 months after the program . Compared to junior respondents in the control group , those in the experimental group positively modified their attitude , perceived behavioral control , personal normative beliefs , perceived role beliefs , anticipated regret and intention with respect to postponing sexual intercourse and with respect to condom use , as well as perceived self-efficacy to negotiate both behaviors . Compared to senior respondents in the control group , those in the experimental group showed a significant positive modification of all the above variables except perceived behavioral control ( indirect measure ) , anticipated regret and intention with respect to postponing sexual intercourse . At post-test , seniors in the experimental group were more likely to use condoms on a regular basis than those in the control group . Program effects occurred among both sexes , but a few differences in response were observed among males and females . Results suggest this type of theory-based program is effective in modifying psychosocial variables related to postponing sexual intercourse and related to condom use among adolescents . Personal involvement in design ing intervention appears to be effective in modifying the behavior of peer educators PURPOSE To determine whether adolescents '  normative beliefs about abstinence and condoms , their personal risk perception , and safer sex practice s changed after the implementation of a peer sexual health education intervention implemented in Zambian secondary schools . METHODS The peer intervention was implemented during the first week of September 2000 in Lusaka , Zambia . A quasi-experimental , longitudinal panel design was used to evaluate its impact . Three schools were r and omly assigned to the intervention condition and two to the control condition . Three rounds of data from male and female adolescents in grade s 10 and 11 were collected at baseline in July 2000 , at first follow-up in the second half of September 2000 , and at second follow-up in early April 2001 . A total of 416 respondents aged 14 - 23 ( at baseline ) were interviewed in all three survey rounds . A mixed-effects logistic regression growth curve analysis was used to calculate adjusted odds ratios to compare intervention and control groups on the outcome variables . RESULTS Student self-reports showed positive changes in normative beliefs about abstinence immediately after the intervention , and these improvements were largely sustained until 6 months after the intervention . Students became more likely to approve of condom use and to intend using condoms immediately after the intervention , but these positive outcomes could not be sustained during the 6 months that followed the intervention . Normative beliefs regarding condom use took longer to develop : these were only observed at 6 months follow-up . Students reported reductions in multiple regular partnerships . There was no change in condom use . CONCLUSIONS A single session school-based peer sexual health intervention result ed in the development of normative beliefs about abstinence that were sustained over a 6-month period . Normative beliefs about condoms took longer to develop . More regular efforts may be required to sustain the approval of , and the intention to use , condoms . The intervention was successful in reducing multiple regular partnerships 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 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 This study assessed the effects of 3 theoretically grounded , school-based HIV prevention interventions on inner-city minority high school students ' levels of HIV prevention information , motivation , behavioral skills , and behavior . It involved a quasi-experimental controlled trial comparing classroom-based , peer-based , and combined classroom- and peer-based HIV prevention interventions with a st and ard-of-care control condition in 4 urban high schools ( N = 1,532 , primarily 9th- grade students ) . At 12 months postintervention , the classroom-based intervention result ed in sustained changes in HIV prevention behavior . This article discusses why both of the interventions involving peers were less effective than the classroom-based intervention at the 12-month follow-up and , more generally , suggests a set of possible limiting conditions for the efficacy of peer-based interventions 
    Output:
    
Most interventions produced improvements in knowledge , attitudes and intentions .
Despite promising results in some trials , overall findings do not provide convincing evidence that peer-led education improves sexual outcomes  among adolescents .