Research Proposal

Children and Youth Services Review 34 (2012) 1646–1658

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Children and Youth Services Review

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Effectiveness of antibullying school programmes: A systematic review by evidence levels

Jose Antonio Jiménez Barbero a,⁎, Jose Antonio Ruiz Hernández a, Bartolomé Llor Esteban a, María Pérez García b

a University of Murcia, Faculty of Pshychology, Espinardo, CP: 30100 Murcia, Spain b University of Murcia, Faculty of Medicine, Espinardo, CP: 30100 Murcia, Spain

⁎ Corresponding author at: Plaza Vistabella, 17, 2L, C Spain. Tel.: +34 646350366.

E-mail addresses: [email protected] (J.A. Jimé (J.A. Ruiz Hernández), [email protected] (B. Llor Esteban), m (M. Pérez García).

0190-7409/$ – see front matter © 2012 Elsevier Ltd. All doi:10.1016/j.childyouth.2012.04.025

a b s t r a c t

a r t i c l e i n f o

Article history: Received 10 February 2012 Received in revised form 14 April 2012 Accepted 20 April 2012 Available online 27 April 2012

Keywords: Systematic review Intervention programme School violence Prevention Attitudes Effectiveness

Increasingly more educational centres are, therefore, carrying out programmes aimed at preventing or reducing violence in schools. This study seeks to examine the efficiency of such programmes in Primary and Secondary schools. The method- ology used is the systematic search of electronic databases (Medline, Trip Database, Cochrane, Academy Search Premier, PsycINFO, ERIC and PsycARTICLES) for studies published after January 1, 2000, on the assessment of the effectiveness of school interventions to prevent or reduce violence and bullying. The study population comprises school-age (6–16 years) children and adolescents of both sexes. Initially, 299 articles were detected that met the inclusion criteria and that had been independently peer-reviewed. For the final evaluation, 32 studies were selected which met the previously established selection and quality criteria, and analysed by level of evidence. The review finds evidence of the efficiency of the programmes assessed, although serious limitations are also detected, which should be taken into consideration when designing future interventions. The likelihood of success is enhanced when all the disciplines of a centre are involved, and also the parents. It is also essential to adapt the diverse programmes to the social and cultural characteristics of the school population in which the programme is to be carried out. Finally, the findings indicate the need for continuity in the programmes if their long-term efficiency is to be guaranteed.

© 2012 Elsevier Ltd. All rights reserved.

1. Introduction

School violence includes behaviours that cause physical and emo- tional harm, ranging from verbal aggression, humiliation, ostracism, physical harm and destruction of property (Benbenishty & Astor, 2005), and including various categories such as classroom disruption, disciplinary problems and maltreatment among classmates (Olweus, 1993).

We are facing a phenomenon that has probably always been present in schools, although it has become the subject of increasing attention and a social alarm in recent years. Several studies have analysed its prevalence finding that 20 to 30% of pupils have been involved in violent episodes, ranging from simple verbal intimidation to physical or sexual aggression (Currie et al., 2008; Department of Health and Human Services & Center for Disease Control and Prevention, 2006; Ruiz, Exposito, & Bonache, 2010).

P: 30820, Alcantarilla, Murcia,

nez Barbero), [email protected] [email protected]

rights reserved.

The consequences it may have for children's mental health and future behaviour must also be considered (Abada, Hou, & Ram, 2008; Östberg, 2003). Some studies show that extended exposure to violence is linked to the development of: (a) emotional and psychosomatic prob- lems in victims and bullies alike (Bond, Carlin, Thomas, Rubin, & Patton, 2001; Gini & Pozzoli, 2009); (b) low self-esteem, depression and suicid- al tendency (Brunstein, Marrocco, Kleinman, Schonfeld, & Gould, 2007; McMahon, Reulbach, Keeley, Perry, & Arensman, 2010); and (c) antiso- cial behaviours, which lead to legal, economic and social problems (Cunningham & Henggeler, 2001).

All of this has led to a heightened awareness of this problem in recent years and the proliferation of prevention programmes (Farrell, Meyer, Kung, & Sullivan, 2001). Habitually, the main components of these inter- ventions are: (a) globally focused policies emphasizing the democratic participation of all school members, which are generally the main part of any long-term interventions; (b) the improvement of the classroom atmosphere, based on pupil–pupil and teacher–pupil relations; (c) the in- troduction of peer support systems; (d) intervention in the recreational area or the school surroundings; (e) pro-social activities in the classroom, as part of the curriculum; and (f) specific work with bullied students or those at risk of being bullied (Cowie, 2000; Cunningham et al., 1998).

Despite efforts to establish them in schools, there is a notable lack of evaluation of these programmes, so the effectiveness of which was

1647J.A. Jiménez Barbero et al. / Children and Youth Services Review 34 (2012) 1646–1658

really unknown (Surgeon General, 2001). The United States' Agency for Healthcare Research and Quality (2010) indicates that meta- analyses of randomized clinical trials (RCTs) are the studies that offer the best scientific evidence of therapeutic interventions, fol- lowed by the RCTs themselves. Yet, given their scope and cost, RCTs are beyond the means of many organisations, which are obliged to rely on published reviews.

The aim of our study is to examine the effectiveness of the interven- tion and violence prevention programmes carried out in the last decade. It continues and updates earlier studies (Scheckner, Rollin, Kaiser-Ulrey, & Wagner, 2002; Wilson, 2000). Studies published since the beginning of 2000 up to the present were evaluated, selecting them on the basis of the quality of their methodological design and on their level of scientific evidence. This allows us to establish the degrees of recommendation of the various programmes (National Institute for Clinical Excellence (NICE), 2008).

2. Methods

2.1. Inclusion criteria

Studies were included in this review if they fulfilled the following criteria: (a) in empirical studies, the aim had to be the evaluation of the effectiveness of an intervention programme in reducing violence in the school environment; (b) in review studies, the main aim required was to examine the effect of school violence prevention or reduction programmes; (c) the evaluated interventions had to directly target the study population (Primary or Secondary school pupils), not the teachers and parents.

2.2. Search strategy

A systematic search was made through the following electronic databases: Medline, Trip Database, Cochrane, Academy Search Premier, PsycINFO, ERIC and PsycARTICLES. The keywords and terms used were: “bullying”, “school violence”, “attitudes toward violence and adoles- cents”, “intervention or prevention program and self-esteem or empa- thy”, among others. In order to guarantee the currency of the findings, the search was restricted to works published after January 1, 2000. The titles were examined, as were the abstracts when available, and those that did not meet the criteria were rejected.

2.3. Selection criteria

The complete texts of the accepted articles were carefully read, and the lists of references were studied to identify possible relevant articles not detected by our initial search. The selection of studies was made by two independent reviewers following two stages:

1) Level of evidence: We used the categories proposed by the Agency for Healthcare Research and Quality (2010) in order to limit the review to articles that offered a high level of scientific evidence: (1A) meta-analysis of randomized, controlled clinical trials; (1B) ran- domized controlled clinical trials; (2A) suitably designed, non- randomized controlled studies; and (2B) uncontrolled studies, such as pre-post studies and cohort studies.

2) Methodological quality: Two independent reviewers assessed the methodological quality of the studies selected with a high inter- rater reliability (Pearson correlation coefficient, r=0.83), using the following evaluation criteria: - For studies of 1A level of evidence (reviews), the criteria used were those described by Jadad, Moher, and Klassen (1998) for sys- tematic reviews, which assign a quality score from 0 to 8. Studies that scored below 4 were rejected. Meta-analyses of randomized clinical trials were included at this level, as were other meta- analyses of prospective studies or systematic reviews of special

importance, provided they reached the required score on this scale.

- For studies of 1B level of evidence (RCTs), studies were included if they fulfilled at least one of the following conditions: (a) A score of 6 or above on an ad hoc scale of methodological

quality based on the guide published by the University of York in 2001 for the preparation of systematic reviews (NHS Centre for Reviews and Dissemination, 2001). The scale comprised 10 items: (1) operative definition of the constructs and terms used in the study; (2) appropriate method for sample selection; (3) appropriate sample size; (4) a priori distinction of sub-groups or use of suitable clustering tech- niques; (5) validity of the evaluation (direct collection of information by the researchers); (6) reliability of the evalua- tion (use of a validated tool and/or a high level of internal con- sistency to evaluate the intervention); (7) follow-up of the results; (8) use of outcome measures that match the aim of the study; (9) appropriate statistical analysis; and (10) suit- able presentation of the findings through graphs or similar.

(b) A score of 3 or above on the scale of Jadad et al. (1996), for randomized clinical tests.

- For the evaluation of the quality of the quasi-experimental studies (2A and 2B levels of evidence) the ad hoc quality scale was used. Articles scoring 6 or above were included in the review.

2.4. Tabulation and analysis of the information

The studies selected were grouped according to their level of scien- tific evidence (1A, 1B, 2A and 2B) and methodological design.

The data from each study were arranged according to the following categories: date and country of study; quality of the methodological de- sign; research aim; name of the prevention or intervention programme evaluated; sample size and age of the study population.

The analysis of the studies selected was descriptive, as meta-analysis was not possible due to the heterogeneity of the results.

3. Results

The electronic search initially returned 9386 publications. After reviewing the titles, abstracts and references, 299 potential articles were identified. Of these, 245 were excluded due to not having a meth- odological design at the levels of evidence 1A, 1B, 2A or 2B. Of the remaining 54 studies, 32 were finally selected that fulfilled the criteria required. Of these, there were 2 meta-analyses of RCTs (1A level of ev- idence), 2 meta-analyses of prospective studies, 1 systematic review, 12 RCTs (1B level of evidence), 11 non-randomized controlled studies (2A level of evidence), and 4 pre-post uncontrolled studies or studies of cohorts (2B level of evidence) (see Fig. 1).

3.1. Level of evidence 1A: meta-analysis of RCT and systematic reviews

3.1.1. Description of the studies We found 5 studies that fulfilled the inclusion criteria for this cate-

gory. Of these, two are meta-analyses of RCTs, which constitute the maximum level of evidence (Mytton, DiGuiseppi, Gough, Taylor, & Logan, 2006; Park-Higgerson, Perumean-Chaney, Bartolucci, Grimley, & Singh, 2008). Due to their interest and their relation to the aim of the study, we also include two meta-analyses of prospective studies (Merrel, Gueldner, Ross, & Isava, 2008; Ttofi & Farrington, 2011) and one systematic review of prospective studies (Vreeman & Carroll, 2007). Details are shown in Table 1.

The 2 meta-analyses of RCTs (Mytton et al., 2006; Park-Higgerson et al., 2008) included 82 randomized clinical trials that assess the efficien- cy of violence prevention programmes in schools. The meta-analysis by Merrel et al. (2008) and the systematic review by Vreeman and Carroll (2007) attempt to assess school interventions aimed at decreasing

22 Articles excluded for not meeting the quality criteria: -Medline: 5 -Academy Search Premier: 4 -PsycINFO: 5 -ERIC: 5 -PsycARTICLES: 3

32 articles included: -Medline: 4 -Cochrane: 6 -Academy Search Premier: 3 -Tripdatabase: 3 -PsycINFO: 6 -ERIC: 4 -PsycARTICLES: 2 - Reference lists: 4

54 articles reviewed due to their methodological quality: -Medline: 9 -Cochrane: 6 -Academy Search Premier: 7 -Tripdatabase: 3 -PsycINFO: 11 -ERIC: 9 -PsycARTICLES: 5 - Reference lists: 4

245 articles excluded because they did not belong to the methodological categories: -Medline: 31 -Cochrane: 3 -Academy Search Premier: 15 -Tripdatabase: 15 -PsycINFO: 93 -ERIC: 78 -PsycARTICLES: 8 - Reference lists: 2

299 studies that met the inclusion criteria: -Medline: 40 -Cochrane: 9 -Academy Search Premier: 22 -Tripdatabase: 18 -PsycINFO: 104 -ERIC: 87 -PsycARTICLES:13 - Reference lists: 6

9,386 potentially important publications, identified via electronic search: Medline (1061); Cochrane (32); Tripdatabase (326); Academic Search Premier (4911), PsycINFO (1578), ERIC (1396), PsycARTICLES (82)

9,093 publications excluded on the basis of titles and abstracts, which did not meet the inclusion criteria

6 publications selected from the reference lists

Fig. 1. Search results.

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bullying. Lastly, the most recent contribution is the meta-analysis by Ttofi and Farrington (2011), which investigates the effectiveness of the com- ponents of the intervention programmes.

The ages at which the programmes were applied range from 5 to 16 years. In the meta-analysis performed by Mytton et al. (2006), the age range was 5–12 years, whereas, in those published by Park- Higgerson et al. (2008) and Ttofi and Farrington (2011), it was 6–16 years. Merrel et al. (2008) worked with 6–12-year-olds, and the systematic review by Vreeman and Carroll (2007) focuses on a target population ranging from 6 to 13 years.

In order to assess the effectiveness of the diverse interventions, the studies under review used the following main measurements of outcomes: incidence of school bullying, victimization, aggressive or externalizing behaviour, physical or relational aggression, knowl- edge and attitudes about violence and bullying at school, both of the schoolchildren and the school staff. Other measures used were assessment of school performance, emotional problems (anxiety, depression…), social and peer group acceptance, positive peer in- teraction, perception of safety, self-esteem, empathy and parental involvement.

3.1.2. Effectiveness of the interventions evaluated The study by Mytton et al. (2006) concludes that aggressive behav-

iour was significantly reduced in the intervention groups compared to the control groups in 34 of the 56 RCTs analysed, and these results were maintained in the 7 studies that included follow-up. The authors report that the secondary school prevention programmes aimed at reducing aggressive behaviour can lead to significant improvements and they conclude that the most effective interventions are those aimed at improving social relations and social skills.

Ttofi and Farrington (2011) also report positive findings, in this case, in the reduction of bullying and victimization. They highlight that inten- sive programmes and programmes that incorporate meetings with par- ents, firm disciplinary measures and greater supervision by teachers of recreational areas are the most effective. Vreeman and Carroll (2007) re- port that multidisciplinary interventions achieve the best results, where- as those based on adaptations of the syllabus seem to prove less effective, with significant results in only 4 of the 10 interventions examined.

Merrel et al. (2008) conclude that there is evidence to support the effectiveness of school interventions to improve social competence, self-esteem and peer acceptance, although they admit that only one

Table 1 Papers reviewed at level of evidence 1A: meta-analyses and systematic reviews of RCTs.

Authors, year of publication

Papers reviewed Age Aims Main results

Mytton et al. (2006) 56 RCTs/meta-analysis. 5–12 The effects of school violence prevention programmes for children identified as being aggressive or at risk of being so.

–Prevention programmes to reduce aggressive behaviour are effective (SMD=−0.41, CI(95%)= −0.56 to −0.26). –Interventions to improve social skills are more effective than those that teach skills to avoid responding to provocations.

Vreeman and Carroll (2007) 26 papers reviewed without meta-analysis: –9 RCTs –11 pre-post with control group –2 cohort studies –4 pre-post quasi-experimental studies.

6–13 To evaluate school interventions to decrease bullying.

–4 curriculum-based interventions showed a signifi- cant reduction of bullying. –7 multidisciplinary interventions achieved de- creases in bullying. –4 interventions based on increasing social skills achieved no significant changes. –1 study based on tutoring showed a decrease in victimization.

Park-Higgerson et al. (2008) 26 RCTs/meta-analysis. 6–16 The characteristics of school programmes aimed at prevention of violence.

–No significant effects were reported for 4 of the 5 characteristics of the programmes examined. –Only single-focus interventions had any effect on aggressive and violent behaviour (ES=−0.15⁎⁎).

Merrell and Gueldner (2008) 16 prospective studies/meta-analysis: –2 experimental designs –3 mixed design with control group –11 quasi-experimental designs.

6–12 The effectiveness of anti-bullying school interventions.

–Significant positive effects for only one third of the variables. –Main variables with positive results: knowledge of bullying prevention (ES=1.52), global self-esteem (ES=1.08) and perception of abusive conducts (ES=0.35). –Remaining measures showed no significant changes.

Ttofi and Farrington (2011) 53 prospective studies: 44 studies/ meta-analysis –17 RCTs –21 pre-post+CG –4 (other controlled studies) –11 cohorts.

6–16 The effectiveness of the programme components.

–The most intensive programmes were more effective, as were those that included meetings with parents (OR=1.57⁎⁎), firm disciplinary measures (OR=1.59⁎⁎) and improved supervision of recreational areas (OR=1.53⁎⁎).

Abbreviations: RCT, randomized clinical trial; CG, control group; SMD, Standardised Mean Difference; ES, Effect Size. ⁎⁎ pb0.001.

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third of the variables measured showed positive changes following pro- grammes aimed at reducing bullying. They underline that, whilst these may be able to influence awareness, knowledge and self-perception of competence to cope with bullying, they cannot be expected to have a drastic influence on the incidence of bullying and victimization.

Lastly, Park-Higgerson et al. (2008) find no significant effects for four of the five characteristics examined in the prevention programmes.

3.1.3. Differences according to age and gender Of the five studies reviewed, only three interpret the findings in

terms of age and gender. Of these, two meta-analyses (Mytton et al., 2006; Park-Higgerson et al., 2008) find no gender differences in the effect size, although they do highlight age-related differences. Park- Higgerson et al. find that the effectiveness of the programmes is greater in children of 9 years and above, whereas Mytton et al. conclude that the improvements are more significant in the follow-up among Second- ary school students.

Vreeman and Carroll (2007) suggest that the age differences ob- served in the effectiveness of the intervention are due to the focus of the intervention, as programmes based on social skills obtain more positive outcomes among younger children, who, notwithstanding, respond worse to interventions based on the cognitive-behavioural model. As regards gender, the same study finds that girls seem to respond better than boys to multidisciplinary interventions.

3.2. Level of evidence 1B: randomized clinical trials (RCTs)

3.2.1. Description of the studies In the second level of evidence, we include 12 randomized clinical

trials (RCTs) (see Table 2). In 8 of the articles, the authors establish as their main aim the evaluation of the impact of an anti-bullying school intervention (Baldry & Farrington, 2004; Berry & Hunt, 2009;

DeRosier, 2004; Farrell, Meyer, & White, 2001; Fekkes, Pijpers, & Verloove-Vanhorick, 2006; Frey et al., 2005; Hunt, 2007; Stevens, Van Oost, & De Bourdeaudhuij, 2000). A further 3 studies evaluate the effectiveness of a bullying and school violence prevention programme, (Beets et al., 2009; Jenson & Dieterich, 2007; Teglasi & Rothman, 2001). Lastly, one study compares three types of intervention: a pro- gramme designed by the authors (Creating a Peaceful School Learning Environment) versus school psychiatric consultancy versus habitual intervention (Fonagy et al., 2009).

The age of the samples ranges from 8 to 16 years: seven interven- tions were evaluated in Primary schools, three in Secondary schools and two in Primary and Secondary schools.

The main outcome measures in the evaluation of bullying or intimi- dation at school were: frequency and type of bullying and victimization, exposure to bullying, frequency of aggressive and violent behaviours, frequency of maladaptive responses to episodes of bullying and vio- lence, bullying-related beliefs (acceptance of bullying, witness's respon- sibility, adult's perceived responsibility), attitudes towards violence and bullying-related behaviours (direct and indirect aggression and victim- ization). Other measures used were behaviour inside and outside the classroom, behavioural problems, use of drugs, interaction skills, self- effectiveness/self-perception/self-esteem, anxiety and awareness.

3.2.2. Effectiveness of the interventions evaluated Significant differences were found between the intervention group

and the control group in nine of the interventions evaluated (Beets et al., 2009; Berry & Hunt, 2009; DeRosier, 2004; Farrell, Meyer, & White, 2001; Fekkes et al., 2006; Fonagy et al., 2009; Frey et al., 2005; Stevens, Van Oost, & De Bourdeaudhuij, 2000; Teglasi & Rothman, 2001). Follow-ups were carried out in eight of these, and the findings were maintained in only four cases. Noteworthy is the study by Fonagy et al. (2009), which compares a school anti-bullying programme

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(CAPSLE) with two other interventions, finding that CAPSLE achieved a greater reduction in victimization, aggression and the number of ag- gressive onlookers.

The other three studies evaluated obtained no significant results (Baldry & Farrington, 2004; Hunt, 2007; Jenson & Dieterich, 2007).

3.2.3. Differences according to age and gender Frey et al. (2005) report that males are more sensitive to interven-

tion programmes, whereas two other studies (Beets et al., 2009; Farrell, Meyer, & White, 2001) conclude that there are no significant gender differences in the effectiveness of the intervention, although greater stability was observed in boys during the follow-up. As for age, older children (13–15) seem to respond better (Baldry & Farrington, 2004; Frey et al., 2005) although one study declares that the changes are most stable in the follow-up of younger children (Stevens, Van Oost, & De Bourdeaudhuij, 2000).

3.3. Level of evidence 2A: controlled, non-randomized prospective studies

3.3.1. Description of the studies At this level of evidence, we chose 11 studies (see Table 3) with anal-

ogous aims, thus allowing inter-comparison. In these studies, the authors declare their main goals to be: (a) to

analyse the impact of school programmes aimed at reducing violence and bullying (Ju, Wang, & Zhang, 2009; Sapouna et al., 2010; Stanbury, Bruce, Jain, & Stellern, 2009; Stevens, De Bourdeaudhuij, & Van Oost, 2000; Twemlow et al., 2001); (b) to evaluate the effectiveness of bullying prevention programmes (Bauer, Lozano, & Rivara, 2007; Evers, Prochaska, Van Marter, Johnson, & Prochaska, 2007; Menesini, Codecasa, Benelli, & Cowie, 2003; Rahey & Craig, 2002); (c) to study the impact of an anti-bullying programme on school achievement (Fonagy, Twemlow, Vernberg, Sacco, & Little, 2005); and (d) to raise awareness and perception of self-effectiveness when intervening in bullying situations (Andreou, Didaskalou, & Vlachou, 2008). The age range of the study samples was 6 to 16 years. Five interventions were performed in Primary schools (6–11 years), three in Secondary schools (11–16 years) and three in Primary and Secondary schools (6–16 years).

The main measures of outcomes in these studies were: bullying be- haviour, the frequency of physical and verbal aggressions, the descrip- tion and characteristics of victimization, the places where this occurs, attitudes towards bullying, empathy, the roles of the participants in the bully–victim relationship, peer interaction and perception of self- effectiveness to intervene in bullying incidents.

Other associated variables were also measured, such as the percep- tion of safety, commitment and school performance, disciplinary problems, coping strategies, knowledge of bullying, problems of exter- nalizing and internalizing behaviours and the positive reinforcements employed by the school staff.

3.3.2. Effectiveness of the interventions evaluated Statistically significant results were obtained in most of the mea-

sures in nine of the studies, of which only five included a follow-up, with the changes persisting in three of these. However, in two studies, the results of the intervention showed no significant differences (Bauer et al., 2007; Rahey & Craig, 2002).

3.3.3. Differences according to gender and age Regarding age, Rahey and Craig (2002) and Menesini et al. (2003)

indicate that victimization tends to decrease in older children. The latter paper also reports that episodes of bullying increase in older children, whilst the role of the defender and anti-bullying attitudes prevail more among younger children. Lastly, Stevens, De Bourdeaudhuij, and Van Oost (2000) find positive changes in bullying and victimization only for Primary schools (i.e., children aged 6–11 years).

There is a disparity in the results of the diverse authors in terms of gender. Rahey and Craig (2002) report better results for girls;

Stanbury et al. (2009) only obtained significant changes in girls; howev- er, Menesini et al. (2003) report that boys were more sensitive to the intervention.

3.4. Level of evidence 2B: non-controlled studies and studies of cohorts

3.4.1. Description of the studies At this level, we selected three studies of cohorts (Beran, Tutty, &

Steinrath, 2004; Bowllan, 2011; Metzler, Biglan, Rusby, & Spraque, 2001) and one pre-post study without a control group (Salmivalli, Kaukiainen, & Voeten, 2005), whose goal was to determine the efficien- cy of intervention or bullying prevention programmes (see Table 4).

The age ranges studied vary between 9 and 14 years, with two studies carried out in Primary and two in Secondary schools.

In order to evaluate the effectiveness of the interventions, the fol- lowing measures were used: prevalence of bullying, school atmosphere, physical or verbal aggressions, perceived safety, coping strategies, atti- tudes towards victims and bullies, beliefs about self-effectiveness in intervening in situations of aggression, roles those participating in bullying, disciplinary records related to bullying and the degree of implementation of the programme.

3.4.2. Effectiveness of the interventions evaluated Statistically significant results were obtained for the four studies se-

lected. The variables most sensitive to the interventions were frequency of observed and experienced bullying, attitudes towards victims and bullies and the number of verbal and physical aggressions. In three of the studies, a follow-up was carried out and the findings were reported.

3.4.3. Differences according to gender and age Only the study by Bowllan (2011) reports gender and age differences,

with better results obtained by girls of younger ages (12–13 years) than by the remaining subjects of the sample.

4. Discussion

The studies reviewed at the various levels of evidence generally coincide that school programmes aimed at reducing violence can pro- duce beneficial effects in the overall social environment of schools. Thus, the most efficient interventions are those that are developed from a multidisciplinary perspective or global focus and that are di- rected at improving social and interpersonal skills and at modifying attitudes and beliefs.

As in previous studies ahead Rigby (1997), the most sensitive vari- ables in the interventions examined seem to be those related to atti- tudes, beliefs and behaviours. Within this concept, students' attitudes and beliefs about bullying, destructive or intimidating behaviour and the spectator's role are noteworthy. Even in those cases in which the results are modest or nonsignificant for these measures, some authors consider that small changes in attitude within the peer group may con- tribute to general changes in bullying dynamics (Farrell, Meyer, & White, 2001; Frey et al., 2005). Nevertheless, these changes are complex due to the difficulty of their continuity over time unless accompanied in the programme by techniques for maintaining behaviour, such as antic- ipating risk situations, positive reinforcement of peers who intervene to put a stop to the bullying, etc. (Stevens, Van Oost, & De Bourdeaudhuij, 2000). The authors reviewed herein also highlight the importance of the role of the passive onlooker in bullying (Cowie, 2000; Twemlow et al., 2001). Spectators' silence or complicity may imply a strong support for the bullies and indirectly favour a violent culture. Menesini et al. (2003) propose a global approach based on social relationships among peers in order to help to break this pact of silence and foster peer re- sponsibility and empathy.

Significant results in school programmes were also obtained in the frequency of violent behaviour. In this respect, several authors find that the interventions are more effective among adolescents showing

Table 2 Papers reviewed at level of evidence 1B: randomized clinical trials.

Author/country Aim Sample size Age Programme/intervention Duratio /follow-up Significant results

Stevens, Van Oost, and De Bourdeaudhuij (2000) Belgium

The effect of anti-bullying inter- vention programme in children's attitudes.

13 PS 11 SS N=2193

10–16 The curriculum-based interven- tion among peers.

7 mont s. 1-year llow-up.

Significant changes in the variables measured at post-test 1 (pro-bully factor=1.73⁎; pro- victim factor=3.43⁎), which dis- appeared at follow-up, except for PS, where they were maintained.

Farrell, Meyer, et al. (2001), Farrell, Meyer, and White (2001) USA

The impact in 6th year pupils of an intervention programme on knowledge, attitudes and behaviours concerning violence.

3 SS N=626: –IG=305 –CG=321

10–15 Evaluation of Responding in Peaceful and Positive Ways (RIPP).

7 mont s. 6- and -month follow-up.

Reduction of disciplinary violations in the IG: –Reduced participation in a fight: OR=2.5⁎⁎. –Increased participation in peer mediation: OR=.6⁎. At post-test, the effects of the in- tervention were almost signifi- cant, especially in boys.

Teglasi and Rothman (2001) USA

The effectiveness of a school programme to reduce aggressive behaviour in the classroom.

1 PS N=59 –IG=8 aggressive –CG=8 non-aggressive

9–10 The Structure/Themes/Open Communication/Reflection/ Individuality/ Experiential Learning/Social Problem-Solving (STORIES) Programme.

15 wee . No follo -up.

Significant reduction of externalizing and anti-social be- haviours for non-aggressive chil- dren (F=10.02⁎; F=6.36⁎, respectively). Among the aggressive children, there were significant improve- ments in the IG.

Baldry and Farrington (2004) Italy

Evaluation of an intervention programme to reduce bullying and victimization.

2 MS and 1 SS N=239 –IG=131 –CG=106

10–15 Ad hoc intervention: Develop social skills to understand the negative consequences of bullying.

3 days. No follo -up.

Reduction of some types of victimization, but only in older subjects (14–15 years), (F=4.83⁎). Increase in bullying and victimization among younger subjects (11–13 years), (F=8.31⁎⁎; F=10.37⁎⁎, respectively).

DeRosier (2004) USA

The effectiveness of school group intervention based on social skills for children suffering from social anxiety and bullying.

11 PS N=381: –IG=187 –CG=194

8 Social Skills Group Intervention (S.S.GRIN).

6 mont s. 1-year llow-up.

Increased peer friendliness (F=5.13⁎), self-esteem (F=6.46⁎), and self-efficacy (F=4.03⁎), and lower social anxiety (F=4.16⁎) and anti-social affiliations (F=4.28⁎) in the IG.

Frey et al. (2005) USA

The impact of a school programme aimed at: –Reducing bullying and destructive behaviours of the bystanders. –Promoting pro-social behav- iours. –Increasing socio-emotional skills of children involved in bullying.

6 PS N=1126: –IG=549 –CG=577

8–10 Steps to Respect: A Bullying Pre- vention Programme.

5 mont s. 1-year llow-up.

A decrease in the acceptance of bullying, (F=8.51⁎⁎) and greater intervention by onlookers was observed in the IG when friends were bullied. Recreation area behaviour showed a significant decrease in physical and verbal bullying, (F=5.02⁎).

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Table 2 (continued)

Author/country Aim Sample size Age Programme/intervention Dura on/follow-up Significant results

Fekkes et al. (2006) Holland

The effects of a school anti- bullying programme in Primary schools.

47 PS N=3816 –IG=3816 –CG 1=1552 –CG 2=1050

9–12 Programme based on the Olweus Bullying Prevention Programme.

2 ac emic years. No f low-up.

Reduction of the percentage of bullied children, of victimization and of bullying behaviour. No significant differences at follow-up. Intervention group: –Victims of harassment in the post-test RR=0.75⁎ (0.57–0.78) –Stalking in the post-test RR=0.81⁎ (0.51–1.15)

Hunt (2007) Australia

The educational impact of an anti- bullying programme in Secondary schools.

6 SS N=444 –IG=152 –CG=258

12–15 Ad hoc prepared intervention. 1 ac emic year. 1-ye follow-up.

Non significant distances in most measures.

Jenson and Dieterich (2007) USA

The effects of a bullying and victimization prevention programme based on Primary school children's aptitudes.

28 PS N=1126: –IG=670 –CG=456

8–10 Youth Matters Programme. 2 ac emic years. 12-m nth follow- up.

No significant results in most of the measures over time. Tendency towards a decrease in victimization. Positive change in school environment.

Beets et al. (2009) USA (Hawaii)

The effectiveness of a school programme designed to prevent violent and risk behaviours among Primary school children.

20 PS N=1714: –IG=976 –CG=738

Pre-test: 10–11 Post-test:15–16

The Positive Action Programme. 4 ye s. No f low-up.

Reduction of drug abuse. Decrease in risky sexual behaviour. –Reduction of drug abuse: RR=0.41⁎

–Decreased sexual activity: OR=0.24⁎

Berry and Hunt (2009) Australia

The effectiveness in anxious, bullied boys of a cognitive- behavioural intervention focused on factors that increase vulnera- bility to bullying.

7 SS N=46 (boys): –IG=22 –GC=24

12–14 Confident Kids Programme. 8 we ks. 3-m th follow-up.

Reduction of bullying experiences (F=26.52⁎), of symptoms of anxiety (F=32.88⁎) and depression (F=13.88⁎). No significant differences in self- esteem or maladaptive responses.

Fonagy et al. (2009) USA

The effectiveness of the school psychiatric consultation (SPC) vs. a school programme (CAPSLE) vs. treatment at use (TAU) in order to reduce aggression in PS.

9 PS N=1345: –CAPSLE=563 –SPC=422 –TAU=360

8–10 –SPC –“Creating a Peaceful School Learning” (CAPSLE) –TAU

24 m nths. 36-m nth follow-up.

The intervention programme (CAPSLE) moderated the tendency towards victimization and aggression and reduced the number of aggressive bystanders, compared to other interventions (SPC and TAU): M=101.2(0.45) vs 102.2(0.63) vs 102.7(0.71).

Abbreviations: N, sample size; IG, Intervention Group; CG, Control Group; PS, Primary Schools; MS, Middle School; SS, Secondary Schools; RR, Relative Risk; OR, Odds Ratio M, Mean; F, Fisher–Snedecor's F-test. ⁎ pb0.05. ⁎⁎ pb0.001.

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Table 3 Papers reviewed at level of evidence 2A: non randomized controlled prospective studies.

Author/country Aim Sample size Age Programme/intervention Duration/fo w-up Significant results

Stevens, De Bourdeaudhuij, and Van Oost (2000) Bélgium

The effectiveness of the anti- bullying approach in flemish schools.

9 PS+9 SS N=1104 –1 IG=435 –2 IG=426 –CG=243

10–16 Programme adapted from the Olweus Bully Prevention Programme.

7 months. 1-year follo -up.

Significant reduction of bullying (F=3.44⁎), and victimization (F=2.84⁎) in PS. No significant results in SE. No significant differences between the 1st IG (only inter- vention) and the 2nd IG (with external support and training ses- sions for teachers).

Twemlow et al. (2001) USA

The impact of an anti-violence programme based on learning environment in a PS with the re- sults from a control school.

2 EP N=192: –GI=101 –GC=91

8–10 Psychodynamic/social system interventions against violence.

3 years. Follow-up: the end of each academic ye r.

Significant decrease in discipline problems (51.35% for physical aggressiveness, and 4% for suspensions), and improved academic performance in the school with the intervention, (F=8.50⁎⁎, for Mathematics).

Rahey and Craig (2002) Canadá

The short-term effects of a school anti-bullying programme.

2 Elementary schools (PS and MS ) –N=491: –GI=240 –GC=251

6–13 Ad hoc programme based on “Bully Proofing your School”.

12 weeks. No follow‐u .

No significant reduction in school bullying. Older children (9–13) benefited from the programme whereas younger ones (6–8) showed no significant changes. Changes were observed in some measures of results: victimization, internalization and externalization, which vary according to age and sex.

Menesini et al. (2003) Italy

The effectiveness of school anti- bullying intervention.

2 EM –N=293: –GI=178 –GC=115

11–14 “The Befriending Intervention”. 1 school yea . No follow-u .

The pro-bullying roles and those of the bystander were reduced or remained stable steady in the IG.

Fonagy et al. (2005) USA

The impact of an anti-bullying programme in educational achievement in PS.

5 EP and ES N=2206: –GI=1106 –GC=1100

10–12 The Creating a Peaceful School Learning Environment (CAPSLE)..

5 years. Follow-up: aluation at the end of each acad mic year.

A significant improvement was observed in the academic performance of the IG, (Chi2

=7.19⁎⁎ for Mathematics). Andreou and Didaskalou (2008) Greece

The effectiveness of an intervention that sought to improve awareness, self- reflection and the capacity to solve bullying situations.

10 PS N=454 –CG=206 –IG=248

9–12 Ecological approach. Intervention based on the roles of the bullying participants.

4 weeks. 6-month fol w-up.

Reduction of the role of the passive spectator (F=10.301⁎⁎). Improvement in self-effectiveness beliefs to intervene in bullying situations (F=10.338⁎⁎) Results were maintained at follow-up.

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Table 3 (continued)

Author/country Aim Sample size Age Programme/intervention Duration/follow-up Significant results

Bauer et al. (2007) USA

The effectiveness of a bullying prevention programme.

10 PS N=6518: –IG=4959 –CG=1559

6–11 Olweus Bullying Prevention Programme.

2 years. No follow-up

Intervention had no overall effect on victimization. Significant results were found when the sample was layered by ethnic groups: relational and psychological violence was reduced among white pupils: RR=0.72 (0.53–0.98) and 0.63 (0.42–0.97) respectively.

Evers et al. (2007) USA

The effectiveness of trans- theoretical model based on school interventions to prevent bullying.

12 MS+12 SS N=2452 –CG=792 –1 IG=863 –2 IG=797

11–16 “Build Respect, Stop Bullying”. 1 year: 3 sessions. No follow-up.

Significant reductions in student involvement in bullying, in the roles of the bully, the victim and the passive onlooker both in MS (treatment 1: t=−6.33⁎⁎; treat- ment 2: t=−7.55⁎⁎), and SS (treatment 1: t=−5.33⁎⁎; treat- ment 2: t=−5.69⁎⁎).

Stanbury et al. (2009) USA

A school programme aimed at reducing bullying.

1 SS N=172 –IG=86 –CG=86

13–14 Programme designed to improve empathy among school children.

7 weeks. No follow-up.

Significant differences among girls in bullying behaviour (F=6.887⁎), and at post-test be- tween the IG and the CG, (F=4.499⁎). No differences found among boys.

Ju et al. (2009) China

To reduce the incidence of bullying by establishing a respectful and safe class environment.

1 PS N=354 –IG=233 –CG=121

8–10 Programme designed by researchers based on the “action research” approach.

5 weeks. No follow-up.

Significant reduction of victimization on the journeys to and from school in the IG (t=3.86⁎).

Sapouna et al. (2010) UK–Germany

The effects of virtual teaching aimed at reducing bullying and the general rates of victimization among SS students.

27 PS N=1129: –IG.=509 –CG=560

7–11 “Fun with Empathic Agents to achieve Novel Outcomes in Teaching”: FEAR NOT!

3 weeks. 5-week follow-up.

Significant improvement in the capacity to escape victimization in the IG (RR=1.41 (1.02–1.81)). A dose–response relation was found between the amount of in- terventions with virtual and the capacity to escape victimization (OR=1.09 (1.003–1.18)).

Abbreviations: N, sample size; IG, Intervention Group; CG, Control Group; PS, Primary Schools; MS, Middle Schools; SS, Secondary Schools; F, Fisher–Snedecor's F-test; RR, Relative Risk; OR, Odds Ratio; t, Student's t-test. ⁎ pb0.05.

⁎⁎ pb0.001.

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Table 4 Papers reviewed at level of evidence 2B: uncontrolled studies and studies of cohorts.

Author/ country Aim Sample size Age Programme/ intervention Duration/ follow-up Significant results

Metzler et al. (2001) USA

The effectiveness of a programme involving school staff in order to reinforce positive behaviour among pupils.

3 SS –N=1043: –IG=645 –CG=758

11–14 Effective Behaviour Support Intervention.

1 school year. 1-year follow-up

Increase of appropriate social behaviours (20.4% increase for 6th graders and 27.3% increase for 7th graders) and reduction of physical and verbal bullying in IG (35.2% for 6th graders decrease, and 31.3% for 7th graders decrease). Fewer disciplinary incidences among 7th-year pupils, (F=3.64⁎). Greater perceived safety in the IG, (27.5% for 6th graders increase, and 22.3% for 7tth graders increase).

Beran et al. (2004) Canada

To reduce intimidating behaviours and to create a safe school environment.

4 PS Phase 1 –EC=25 –CC=77 Phase 2 C1=20 C2=70

9–12 Dare to Care: bully proofing your school.

Phase 1: Duration: 3 months. No follow-up. Phase 2: Duration: 1–2 years. Comparison of 2 PS of different programme intervention lengths.

Phase 1: Frequency of bullying reduced in the centre (t=3.84⁎⁎). Attitudes towards victims worsened in the CC at post-test (t=5.79⁎⁎). Phase 2: In C2 (after 2 years of the pro- gramme), more positive attitudes towards victims were recorded than in C1, after 1 year of the programme (F=2.74⁎).

Salmivalli et al. (2005) UK

The effects of an anti-bullying in- tervention programme.

16 PS N=1220

9–12 Global intervention based on the roles played by those involved in bullying.

6 months. 12-month follow-up.

Fewer bullies (ß=−1.72(0.78)), and victims( ß=−0.90(0.50)). Less bullying observed (ß= −0.37(0.21)), and experienced (ß=0.27(0.15)). Improved role of participants (ß=−0.21(0.009) in role of reinforcing).

Bowllan (2011) USA

The prevalence of bullying in MS and the impact of a prevention programme.

1 SS N=270 EC=112 CC=158

12–14 Olweus Bullying Prevention Programme.

1 year. No follow-up.

Significant, positive results among girls in the 7th grade (12–13) on prevalence of bullying (27% decrease) and in the teachers' capacity to identify bullying (48.8% increase).

Abbreviations: N, sample size; EC, Exposed Cohort; CC, Control Cohort; C1, Cohort during first year of programme; C2, Cohort during second year of programme; PS, Primary School; SS, Secondary Schools; t, Student's t-test; ß, regression coefficient; F, Fisher–Snedecor's F-test. ⁎ pb0.05. ⁎⁎ pb0.001.

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1656 J.A. Jiménez Barbero et al. / Children and Youth Services Review 34 (2012) 1646–1658

high levels of violent behaviour (Beets et al., 2009; Farrell, Meyer, & White, 2001). This may be due to the floor effect generated by stu- dents with low levels of aggression. This is consistent with prevention programmes that proved more effective among students with high pre-test levels of aggressiveness (Stoolmiller, Eddy, & Reid, 2000). However, in interventions that were not focused on aggression, Fonagy et al. (2009) report significant reductions in this measure for low-risk Primary school children.

Significant changes in victimization caused by bullying were also observed in the studies reviewed. The authors underline the importance of teaching coping strategies and training in social skills in order to be able to respond to episodes of bullying (Berry & Hunt, 2009; Jenson & Dieterich, 2007), as Olweus reported in previous studies (Olweus, 1993, 1996).

The modulating effect of gender and age was not studied in depth because most of the studies do not find (or do not report) significant differences due to these variables. In the studies that indicate gender differences, most of the authors report better results amongst males (Beets et al., 2009; Farrell, Meyer, & White, 2001; Frey et al., 2005; Menesini et al., 2003), although some studies contradict this (Jenson & Dieterich, 2007; Rahey & Craig, 2002). The reason for these apparently contradictory findings does not seem to lie in the theoretical framework of the interventions, as most of them stem from a pro-social model, based on the development of anti-bullying beliefs and attitudes, or form mixed models that combine the psychodynamic or global approach (Frey et al., 2005; Rahey & Craig, 2002). Nevertheless, we believe that these findings may be due to the fact that the tools used in the evaluation usually measure aggression and direct bullying, which are more frequent among boys, and they ignore indirect violence based on more subtle behaviours, such as isolating or rumours, which are more prevalent among girls (Olweus, 2005). It has been observed that boys usually reveal higher baselines in scales of aggression, bully- ing and victimization (Menesini et al., 2003). This may explain why it is easier to obtain more positive results among boys than girls, as these types of assessment tools are the most common in the studies examined. On the other hand, the gender difference observed in the differential use of violence may be related to girls' greater predis- position to develop internalizing behaviours, in contrast to boys, who usually display externalizing ones (Wasserman, McReynolds, Ko, Katz, & Carpenter, 2005; Zahn-Waxler, Shirtcliff, & Marceau, 2008).

Rahey and Craig (2002) report better results among girls and con- sider that this may be due to the intervention being more adapted to these gender differences. However, an influential factor may be the use of indirect assessment tools, such as questionnaires administered to teachers or parents, who usually give lower scores in victimization and bullying for girls than for boys. This is consistent with the findings of other authors who do not find significant gender differences when the same variable is measured through self-report questionnaires (Elsea & Smith, 1998). This coincides with the conclusions of Frey et al. (2005), who report that boys generally benefit more from the intervention, although girls obtain better results in the acquisition of social skills—a measure that is assessed through teachers' reports.

With regard to age, most of the cases studied that offer findings on this variable report better results among older children (Secondary schools). Indeed, despite the fact that interventions carried out with younger children (Primary schools) produce significant improvement in the acquisition of social skills and increased empathy, no changes are observed in the frequency and severity of bullying and victimization episodes or those of physical and verbal aggression. There are several, apparently contradictory, interpretations of these findings. Some authors state that children continually exposed to situations of bullying, manage to adapt over time and acquire the social and assertive skills necessary to cope with the situation. This would lead to less victimiza- tion when they are older (Jenson & Dieterich, 2007; Smith, Madsen, & Moody, 1999). However, Rahey and Craig (2002) conclude that small children who are victims of bullying can turn into bullies of younger

children as they get older and stronger, thus perpetrating a “cycle of violence”. This would justify the need to administer intervention pro- grammes simultaneously across the entire school age range. This inter- pretation is consistent with the findings of other authors who have carried out programmes at both Primary and Secondary school levels (Stevens, De Bourdeaudhuij, & Van Oost, 2000) and who obtain better results for younger aged children.

5. Conclusions

This review allows us to state that there is evidence for the effective- ness of school interventions aimed at reducing or preventing violence. The most effective interventions appear to be those aimed at improving social and interpersonal skills and modifying attitudes and beliefs. The most sensitive variables used to evaluate the effectiveness of these interventions are those related to attitudes, beliefs and behaviours and, to a lesser extent, victimization and frequency of violent behaviours. With regard to the modulating effects of gender and age on the effective- ness of the programmes analysed, the findings are inconclusive, as most of the studies do not take these variables into consideration. The few that do so indicate that, in terms of gender, there is a better response among males, whereas, in terms of age, older children (Secondary schools) seem to benefit more from the diverse programmes.

6. Recommendations

Our study has revealed certain aspects that need to be borne in mind when designing future interventions:

1) The likelihood of success is greater when all the professional disci- plines of the educational centres and the parents of the children are involved.

2) It is essential to adapt programmes to the social and cultural charac- teristics of the school population in question and to consider any possible influence of age and gender.

3) The long-term effectiveness of interventions is vital. The few studies that include follow-ups generally coincide that the effect decreases when the intervention is not maintained. We suggest that it is neces- sary to adopt measures that favour this continuity, such as reminder sessions or the implementation of prevention or intervention pro- grammes within the academic curriculum.

7. Limitations

This review has a series of limitations that should be taken into account. Firstly, the search strategy restricts the search to articles published in English, which may exclude studies of interest in other languages. Unpublished articles and articles providing low levels of evidence are also excluded. Furthermore, the interventions evaluated were generally performed in not very homogeneous populations. In fact, some were carried out exclusively in Primary or Secondary schools, whereas others covered the whole school-age range, from 6 to 16 years, and therefore include subjects at very different stages of maturity. The populations studied are also of diverse origins (USA, Australia, UK, France, Greece, Canada…) and therefore present diverse social and cultural peculiarities. Finally, due to the heterogeneity of the different programmes evaluated, the diverse models, methodologies and tools used, it is not easy to compare findings or to apply meta-analysis techniques.

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