| Berg et al.86 |
|---|
| Methods | Non-randomised trial: matched comparison group |
| Unit of allocation | Individual |
| Participants’ details | Country: USA
Sample number: 114 (IG); 202 (CG)
Sex: 51% female, 49% male in intervention group
Ethnicity: 47% African American/black; 41% Latino; 12% mixed/white/newly arrived
SES: not stated |
| Intervention details | Description: YARP
Targeted/universal: targeted
Target population: youth aged 14 to 16 years
Provider(s): prevention research educators
Theory: prevention, cognitive and critical theory including: (1) ecological theory; (2) identity theory; (3) learning and instructional theories (including social learning, social construction and multiple intelligence); and (4) critical, transformative theories including voice, empowerment and action research
Training: educators are trained in action research methods and empowerment-oriented, social construction facilitation skills
Setting: community-based after-school and summer programme
Content: participatory action research involving formative community ethnography (e.g. training youth to identify adolescent risk behaviours, develop a collective action plan and carry out activities) as a group, including using research to understand their community better
Length/intensity: 4 hours/day for 8 weeks, 8-month implementation period for action plan
Control: measurement |
| Outcomes | At post intervention (less than unity favours intervention):
Frequency of marijuana use in past 30 days: r = –0.12; p-value = 0.053
Frequency of alcohol use in past 30 days: decrease but not significant |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Not applicable | This was a non-randomised trial |
| Allocation concealment: was the allocation adequately concealed? | Not applicable | This was a non-randomised trial |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | This was a non-randomised trial |
| Incomplete outcome data: were complete data for each outcome reported, and, if not were adequate reasons for incomplete outcome data provided? | No | By outcome: reasons for dropout not reported, and all drug-use outcomes not reported
17.4% attrition overall
Reasons for dropout not reported; however, authors report no differences between groups on dropout characteristics |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Yes | The evaluation discussed collecting outcome data on a variety of substance use measures, but only one is presented in sufficient detail to calculate an effect size |
| Key confounders: Were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Yes | Intervention and control samples matched, and differences between groups used as covariates in analyses |
| Clustering: was clustering of participants accounted for in the analysis? | No | No evidence of accounting for clustering |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
| Cross et al.90 (linked studies: Gottfredson et al.91,92) |
|---|
| Methods | RCT |
| Unit of allocation | Individual |
| Participants’ details | Country: USA
Sample number: 224 (IG); 223 (CG); analysed: 211 (IG); 205 (CG)
Sex: 48% female, 52% male
Ethnicity: 71% African American/black; 17% white; 8% multiracial
SES: 58% received subsidised school meals |
| Intervention details | Description: the All Stars prevention curriculum: an enhanced ASP
Targeted/universal: universal
Target population: pupils aged 11–14 years from five under-performing middle schools
Theory: not stated
Provider(s): a county-level government agency that specialising in providing recreation and leisure activities for youths
Training: 6 hours in tutoring model, 19 hours in running ASP, 3 days in All Stars
Setting: middle schools
Content: leisure activities (e.g. fitness activities, board games, arts and crafts, field trips, computer projects or computer free time, service learning, workforce skills and holiday or other special event celebrations)
Length/intensity: 3 days per week, for 3 hours
Control: monthly ‘fun activity’ at programme |
| Outcomes | At post intervention (less than unity favours treatment):
Any use of alcohol, cigarettes or marijuana in the past month: OR 1.03; p-value = 0.91
Smoking initiation: OR 0.95; p-value = 0.90
Drinking initiation: OR 1.10; p-value = 0.75
Marijuana initiation: OR 0.72; p-value = 0.47
Inhalant initiation: OR 0.73; p-value = 0.17
Other drug initiation: OR 1.73; p-value = 0.40 |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Yes | Random number generator used |
| Allocation concealment: was the allocation adequately concealed? | Unclear | No information provided |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | Unclear | No information provided |
| Incomplete outcome data: were complete data for each outcome reported, and, if not were adequate reasons for incomplete outcome data provided? | No | Sample restricted to post-test questionnaire completers; dropout characteristics analysed but missing data on post-test questions as well
7% attrition overall |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Unclear | We could not assess this with the given information |
| Key confounders: Were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Not applicable | RCT |
| Clustering: was clustering of participants accounted for in the analysis? | Yes | Analysis controlled for site |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | Yes | Unbalanced missing and differential follow-up patterns are present |
| Gottfredson et al.93 |
|---|
| Methods | RCT/non-randomised trial |
| Unit of allocation | Individual and group |
| Participants’ details | Country: USA
Sample number: 239 in IG?, 201 in CG? (only older children)
Sex: 44% female, 56% male in IG; 50% female, 50% male in CG
Ethnicity: 76% non-white in IG, 53% in CG
SES: no information |
| Intervention details | Description: Maryland After School Community Grant Program
Targeted/universal: universal
Target population: elementary- and middle-school children
Theory: not stated
Provider(s): ASP providers
Training: 6 hours in tutoring model, 19 hours in running ASP, 3 days in All Stars
Setting: public schools, community centres
Content: three activity areas: (1) academic assistance; (2) social skill; or (3) character development, and recreational/leisure activities aimed at retaining young people in the programme. Recreational activities mainly included: sports, arts and crafts, in additional to specialty activities, such as entrepreneurial activities, karate, sailing, or soccer
Length/intensity: 3 days/week for 90 sessions (middle school), 4 days/week for 120 sessions (elementary school); average of 3 hours/session
Control: waiting list or community-recruited comparison |
| Outcomes | At post intervention:
Past year variety of drug use:
IG: pre-test 0.036 (SD 0.119, n = 234) post-test 0.038 (SD 0.127, n = 222)
CG: pre-test 0.053 (SD 0.146, n = 199) post-test 0.086 (SD 0.198, n = 173) |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Not applicable | Non-randomised trial |
| Allocation concealment: was the allocation adequately concealed? | Not applicable | Non-randomised trial |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | Non-randomised trial |
| Incomplete outcome data: were complete data for each outcome reported, and, if not were adequate reasons for incomplete outcome data provided? | No | Dropout characteristics analysed, uneven attrition and inadequate treatment of missingness (e.g. imputed means were not reported) |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Unclear | We could not assess this using the information provided |
| Key confounders: Were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Yes | Differences between conditions tested across randomisation and non-random assignment |
| Clustering: was clustering of participants accounted for in the analysis? | No | No evidence of accounting for clustering |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
| Kuperminc et al.95 |
|---|
| Methods | Non-randomised trial |
| Unit of allocation | Individual |
| Participants’ details | Country: USA
Sample number: 86 (IG), 89 (CG) (additionally, 29 girls assigned to mentors)
Sex: 100% female
Ethnicity: 76% non-white in IG, 53% in CG
SES: 80–96% of students attending programme schools lived in economic disadvantage |
| Intervention details | Description: Cool Girls, Inc.
Targeted/universal: universal
Target population: young girls aged 9 to 15 years from disadvantaged and low-income communities
Theory: not stated
Provider(s): community-based organisation
Training: not stated
Setting: public schools
Content: three main components: (1) Girls Club; a comprehensive life skills curriculum covering a range of topics (e.g. positive sexual health, hygiene, conflict resolution, self-esteem and cultural awareness); (2) Cool Scholars: providing homework assistance, individual tutoring and supporting girls to complete projects (e.g. making presentations, journaling and participating in academic tournaments). Participants are also eligible for (3) ‘Cool Sisters’, a one-to-one mentoring programme, after actively taking part in the programme for 1 year. Additional components include: weekend workshops (e.g. computer skills, financial literacy and career development); field trips (e.g. tours of the Cable News Network, the Weather Channel and visits to local museums); special events; and summer programmes
Length/intensity: weekly meetings during the school year
Control: comparators nominated by participants and schools |
| Outcomes | At post intervention (greater than unity favours intervention):
Avoidance of drug use (cigarettes, alcohol, marijuana, cocaine, or inhalants) in past 6 months: OR 0.62 (ns) for full sample; OR 1.53 (ns) for mentored |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Not applicable | Non-randomised trial |
| Allocation concealment: was the allocation adequately concealed? | Not applicable | Non-randomised trial |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | Non-randomised trial |
| Incomplete outcome data: were complete data for each outcome reported, and, if not were adequate reasons for incomplete outcome data provided? | Yes | Dropout characteristics analysed, uneven attrition and inadequate treatment of missingness but multiple imputation carried out |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Unclear | Unable to assess based on provided information |
| Key confounders: were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Yes | Differences between conditions tested using covariates in regression |
| Clustering: was clustering of participants accounted for in the analysis? | Yes | Cluster effects were small and not statistically significant |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
| Rhodes et al.96 (linked studies: Grossman and Tierney;97 Tierney98) |
|---|
| Methods | Randomised trial |
| Unit of allocation | Individual |
| Participants’ details | Country: USA
Sample number: 487 (IG), 472 (CG)
Sex: about 25% female, 75% male
Ethnicity: 45% white; 42% black; 14% Hispanic
SES: 37% welfare recipients, 36% incomes below poverty level |
| Intervention details | Description: BBBS
Targeted/universal: targeted
Target population: young people between 5 and 18 years of age, with minimal social skills, who live in an agency catchment area, with priority given to young people who only have one parent engaged in their life
Theory: matched youth mentoring; based on sex and various other factors such as shared interest, reasonable geographic proximity and same ethnicity
Provider(s): trained community volunteers
Training: initial training on abuse and programme rules, additional training often provided on youth development, monthly supervision
Setting: community
Content: 1 : 1 weekly mentoring aimed at developing the ‘whole person’, with the mentoring relationship is seen is the mechanism that enables the mentor to support the mentee transition from childhood and/or adolescence into adulthood
Length/intensity: weekly meetings with mentor
Control: unmatched children |
| Outcomes | At post intervention:
Initiation of drug abuse: CG mean 11.47%, IG less by 45.8% (p < 0.05)
Initiating alcohol use: CG mean 26.72%, IG less by 27.4% (p < 0.10)
Cigarette smoking: CG mean 17.2%, IG less by 19.7% (p > 0.10)
Number of times hit someone: CG mean 2.68, IG less by 0.85 (p < 0.05)
Number of times involved in a fight: CG mean 1.54, IG less by 0.02 (p > 0.10) |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Unclear | Not enough information was provided |
| Allocation concealment: was the allocation adequately concealed? | Yes | Allocation done by an external survey subcontractor |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | Not possible in this intervention |
| Incomplete outcome data: were complete data for each outcome reported and, if not, were adequate reasons for incomplete outcome data provided? | No | Only people with all measurement occasion included |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Unclear | Could not assess based on provided information |
| Key confounders: Were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Not applicable | Randomised trial |
| Clustering: was clustering of participants accounted for in the analysis? | No | No evidence of accounting for clustering |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
| Rodriguez-Planas78 (linked studies: Maxfield;99,100 Rodriguez-Planas;101 Schirm et al.;103 Schirm and Rodriguez-Planas;104 Schirm and McKie105) |
|---|
| Methods | RCT |
| Unit of allocation | Individual |
| Participants’ details | Country: USA
Sample number: 580 (IG), 489 (CG)
Sex: IG: 52.2%% male, 47.8% female; CG: 55.8% male, 44.2% female
Ethnicity: IG: 26.2% Hispanic, 68.3% Black, CG: 25.7% Hispanic, 67.9% Black
SES: not reported |
| Intervention details | Description: QOP
Targeted/universal: targeted
Target population: youth who met the following criteria: (1) began the ninth grade with a dropout rate of 40% or more; (2) grade point average below the 67th percentile of entering ninth graders; (3) not repeating the ninth grade; (4) not so physically disabled or learning disabled that participation in programme is inappropriate
Theory: youth development model
Provider(s): case managers and mentors, community-based organisations
Training: unclear
Setting: schools and community-based organisations
Content: intensive case management, mentoring and educational, developmental, cultural and recreational and community-based activities. Education services: academic assessment, an individual education plan, one-on-one tutoring and computer-assisted instruction in specific coursework and basic reading and mathematics. Visiting nearby college campuses and other activities designed to promote awareness of and planning for college. Developmental activities: life-skills training, employment-readiness training, cultural awareness and recreation. Community service activities (e.g. visiting the residents of a local nursing home or volunteering at a neighbourhood food bank). Cultural and recreational activities: movies, ice skating, bowling, swimming, sailing, golfing, mountain biking, amusement/water parks, haunted houses, board/computer games, local fairs, picnics, attending sporting events, pizza lunches, dinners in restaurants
Length/intensity: 750 hours per year, or over 14 hours per week on average throughout the year for up to 5 years
Control: no treatment |
| Outcomes | In the fourth year of the demonstration programme (i.e. post intervention):
Near the end of the fourth academic year:
Drinking in past 30 days: 40% (IG) vs. 33% (CG)
Frequent drinking in past 30 days: 11% (IG) vs. 11% (CG)
Binge drinking in past 30 days: 24% (IG) vs. 20% (CG)
Frequent binge drinking in past 30 days: 7% (IG) vs. 5% (CG)
Drunk or high at school in past 12 months: 20% (IG) vs. 20% (CG)
Used an illegal drug in past 30 days: 34% (IG) vs. 28% (CG)
Involved in gang fight in past 12 months: 16% (IG) vs. 14% (CG)
Telephone survey 7 months later:
Binge drinking in past 30 days: 19% (IG) vs. 23% (CG)
Frequent binge drinking in past 30 days: 5% (IG) vs. 4% (CG)
Used an illegal drug in past 30 days: 16% (IG) vs. 19% (CG)
3 to 4 years post intervention:
Binge drinking in past 30 days: 25% (IG) vs. 31% (CG)
Binge drinking on eight or more days in past 30 days: 7% (IG) vs. 5% (CG)
Used an illegal drug in past 30 days: 12% (IG) vs. 18% (CG)
Approximately 6 years post intervention:
Smoked cigarettes or used tobacco in past 30 days: 34% (IG) vs. 34% (CG)
Smoked cigarettes or used tobacco daily in past 30 days: 22% (IG) vs. 24% (CG)
Binge drinking in past 30 days: 31% (IG) vs. 31% (CG)
Binge drinking on eight or more days in past 30 days: 8% (IG) vs. 6% (CG)
Used an illegal drug in past 30 days: 12% (IG) vs. 13% (CG) |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Unclear | No information provided |
| Allocation concealment: was the allocation adequately concealed? | Unclear | No information provided |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | Impossible given the intervention |
| Incomplete outcome data: were complete data for each outcome reported and, if not, were adequate reasons for incomplete outcome data provided? | Yes | Weighted analysis partially accounts for missingness |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Unclear | Could not assess given information |
| Key confounders: Were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Not applicable | Randomised trial |
| Clustering: was clustering of participants accounted for in the analysis? | Yes | Analysis controlled for site |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
| Schwartz et al.77 (linked studies: Millenky et al.;107–109 Perez-Arce et al.110) |
|---|
| Methods | RCT |
| Unit of allocation | Individual |
| Participants’ details | Country: USA
Sample number: 722 (IG), 451 (CG)
Sex: 88.0% male, 12.0% female
Ethnicity: 18.1% Hispanic; 42.3% white; 33.8% black; 5.7% other
SES: 26.4% of families receive public assistance |
| Intervention details | Description: NGYCP YIM programme
Targeted/universal: targeted
Target population: youth 16 to 18 years old who have dropped out or been expelled from school, who are drug free at the time of entry into the programme and not currently on probation or parole for anything beyond juvenile status offences, not serving time or awaiting sentencing, not under indictment or charged and not convicted of a felony or capital offence
Theory: military training model that believes incorporating caring relationships with non-parental adults can contribute to a range of PYD outcomes
Provider(s): National Guard
Training: unclear
Setting: community military-style boot camp
Content; The Pre-ChalleNGe Phase is a 2-week period of orientation and assessment in which young people adjust to an intensive, structured lifestyle required at the programme site. The residential phase is a 20-week period during which youth are working towards their high school diploma or GED and take classes on life skills, health and job skills, while participating in other activities such as physical training, sports, leadership and citizenship activities and community service. The post-residential phase is characterised by a post-residential action plan in which youth identify specific post-residential activities (e.g. GED programme, community college, vocational training, a job, or military service)
Length/intensity: 5 months’ full-time residential, 1 year’s post-residential with job placement and structured mentoring
Control: waitlist |
| Outcomes | At post intervention:
Charged with a violent crime: 3.4% (IG) vs. 3.6% (CG)
Convicted of a violent crime: 1.4% (IG), 1.2% (CG)
Any violent incidents: 54.0% (IG) vs. 57.3% (CG)
Number of violent incidents: 0.9 (IG) vs. 1.3 (CG)
Binge drinking in past 14 days: 2.8% (IG) vs. 4.7% (CG)
Frequent marijuana use in past 12 months: 22.5% (IG) vs. 25.2% (CG)
Ever used other illegal drugs (LSD, cocaine, methamphetamine, amphetamine sulphate, barbiturates, heroin, PEDs): 24.1% (IG) vs. 23.1% (CG)
Frequent illegal drug use in past 12 months: 5.6% (IG) vs. 4.4% (CG)
Charged with a drug crime: 2.9% (IG) vs. 5.3% (CG)
Convicted of a drug crime: 1.4% (IG) vs. 1.9% (CG)
At 18 months post intervention:
Convicted of a violent crime: 2.1% (IG) vs. 2.3% (CG)
Any violent incidents: 48.7% (IG) vs. 44.5% (CG)
Number of violent incidents: 0.9% (IG) vs. 0.8% (CG)
Binge drinking in past 14 days: 26.1% (IG), 30.2% (CG)
Frequent marijuana use in past year: 26.0% (IG), 24.4% (CG)
Ever used other illegal drugs (LSD, cocaine, methamphetamine, amphetamine sulphate, barbiturates, heroin, PEDs): 28.2% (IG) vs. 23.2% (CG)
Frequent illegal drug use in past 12 months: 4.7% (IG) vs. 4.2% (CG)
Convicted of a drug crime: 8.1% (IG) vs. 5.9% (CG) |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Unclear | No information provided |
| Allocation concealment: was the allocation adequately concealed? | Unclear | No information provided |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | Unclear | No information provided |
| Incomplete outcome data: were complete data for each outcome reported and, if not, were adequate reasons for incomplete outcome data provided? | Yes | Weighted analysis partially accounts for missingness, response bias tested |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Unclear | We could not assess this question given the information provided |
| Key confounders: were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Not applicable | Randomised trial |
| Clustering: was clustering of participants accounted for in the analysis? | Yes | Analysis accounted for clustering by site |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
| St Pierre and Kaltreider111 |
|---|
| Methods | Non-randomised trial |
| Unit of allocation | Group |
| Participants’ details | Country: USA
Sample number: 52 (IG), 54 (IG with booster), 55 (CG)
Sex: about 25% female, 75% male
Ethnicity: 45% white; 42% black; 14% Hispanic
SES: 37% welfare recipients, 36% incomes below poverty level |
| Intervention details | Description: Stay SMART is a component of the SMART moves National prevention programme of Boys and Girls Clubs of America
Targeted/universal: universal
Target population: 13-year-old members of Boys and Girls Clubs of America
Theory: personal and social competence approach
Provider(s): Boys and Girls Clubs employees
Training: compulsory training on Stay SMART and yearly training of group leaders on SMART Leaders component
Setting: local ‘clubhouses’ for children
Content: life skills training programme includes structured small group sessions on: gateway drugs; decision-making; advertising; self-image and self-improvement; coping with change; communication skills; social skills (meeting and greeting people; and boy meets girl); assertiveness; relationships; life planning skills. The booster programme SMART Leaders added leadership sessions on: (1) orientation; improving self-image; coping with stress; resisting media pressures; being assertive in pressure situations and (2): resisting alcohol; other drugs; and early sexual activity. Sessions included culturally relevant experiential activities and videos. The video format introducing the session objectives; gave background information; and discussion questions on the video. Participants were also encouraged after sessions to become involved in other prevention activities (e.g. wearing drug-free t-shirt; being drug-free role models; helping with general club activities; helping with specific drug-prevention activities)
Length/intensity: 12 sessions in 3 months; 8 sessions over 2 years added in booster sessions
Control: Boys and Girls Clubs without a prevention programme |
| Outcomes | At post intervention for binary substance-use outcomes:
Alcohol behaviour: not reported
Marijuana behaviour: not reported
Cigarette behaviour: not reported
At 12 months post intervention for binary substance-use outcomes:
Alcohol behaviour: not reported
Marijuana behaviour: IG2 vs. CG: b = 0.80; p-value = 0.19
Cigarette behaviour: IG2 vs. CG: p-value = 0.91; IG2 vs. CG: p-value = 0.54
At 24 months post intervention for binary substance-use outcomes:
Alcohol behaviour: not reported
Marijuana behaviour: IG2 vs. IG: b = 1.09; p-value = 0.12; IG2 vs. CG: b = 1.23; p-value = 0.09
Cigarette behaviour: IG2 vs. IG: b = 0.86; p-value < 0.12; IG2 vs. CG: b = 0.96; p-value < 0.08
Chewing tobacco at all time points: unclear and unreported |
| Notes | Further clarification on outcomes was unavailable |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Not applicable | Non-randomised trial |
| Allocation concealment: was the allocation adequately concealed? | Not applicable | Non-randomised trial |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | Non-randomised trial |
| Incomplete outcome data: were complete data for each outcome reported and, if not, were adequate reasons for incomplete outcome data provided? | No | Only people with all measurement occasions were included |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | No | All outcomes reported, though incompletely |
| Key confounders: were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Unclear | Covariate results inadequately presented |
| Clustering: was clustering of participants accounted for in the analysis? | No | No evidence of accounting for clustering |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | Yes | Outcomes unclear and poorly presented |
| Tebes et al.79 |
|---|
| Methods | Non-randomised trial |
| Unit of allocation | Group: comparator chosen by intervention programmes in neighbouring cities |
| Participants’ details | Country: USA
Sample number: 149 (IG), 155 (CG)
Sex: 47% female, 53% male
Ethnicity: 75.7% African American, 19.7% Hispanic, 3.9% Caucasian
SES: about 13% of parents less than high school educated |
| Intervention details | Description: PYDC
Targeted/universal: universal
Target population: 12- to 16-year-olds
Theory: not stated
Provider(s): community group leaders
Training: 12 hours in curriculum and facilitation, bi-weekly supervision
Setting: public schools
Content: two core components: (1) The Adolescent Decision-Making for the PYDC (ADM-PYDC) a substance-use prevention curriculum which included: (a) programme introduction and overview; (b) understanding and coping with stress and learning stress-reduction strategies; (c) learning the steps of effective decision-making; (d) learning essential information about tobacco, alcohol and other drug use (two sessions); (e) applying the decision-making process to one’s life through identifying positive personal attributes, dealing with job and school stressors, setting positive goals for healthy living and enhancing one’s social networks and resources (four sessions); and (f) programme close and review; and (2) participation in health education and cultural heritage activities e.g. regular field trips to community agencies, civic organisations, businesses and schools to promote learning about community service and understanding one’s cultural heritage. The field trips promoted after-school experiences and access to academic and vocational support, counselling services and participating in intergenerational programmes and community theatre
Length/intensity: school year
Control: ASPs without PYD/adolescent decision-making components |
| Outcomes | At post intervention (less than unity favours intervention):
Use of alcohol in past 30 days: OR 1.179, 95% CI 0.49 to 2.87
Use of marijuana in past 30 days: OR 1.759, 95% CI 0.66 to 4.68
Use of other drugs (amphetamines, cocaine, heroin, non-prescription methadone, hallucinogens, tranquillisers, inhalants) in past 30 days: OR 1.266, 95% CI 0.52 to 3.10
Use of any drug in past 30 days: OR 1.694, 95% CI 0.74 to 3.90
At 3 months post treatment:
Use of alcohol in past 30 days: OR 0.365, 95% CI 0.15 to 0.90
Use of marijuana in past 30 days: OR 0.178, 95% CI 0.08 to 0.42
Use of other drugs in past 30 days: OR 0.188, 95% CI 0.08 to 0.44
Use of any drug in past 30 days: OR 0.289, 95% CI 0.013 to 0.67 |
| Notes | ORs as expressed in study are change indices rather than controlled for baseline values |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Not applicable | Non-randomised trial |
| Allocation concealment: was the allocation adequately concealed? | Not applicable | Non-randomised trial |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | Non-randomised trial; research team responsible for recruiting comparison group |
| Incomplete outcome data: were complete data for each outcome reported and, if not, were adequate reasons for incomplete outcome data provided? | No | Dropout characteristics analysed, but missing data unimputed though missingness roughly balanced across arms |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Yes | Some outcomes (e.g. tobacco) not reported |
| Key confounders: Were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Yes | Propensity score matching entered into level 2 of multilevel model |
| Clustering: was clustering of participants accounted for in the analysis? | No | No evidence of accounting for clustering |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
| Wiggins et al.112 (linked studies: Wiggins et al.46) |
|---|
| Methods | Non-randomised trial: group matched |
| Unit of allocation | Group |
| Participants’ details | Country: UK
Sample number: 1637 (IG), 1087 (CG)
Sex: IG: 62% male, 38% female; CG: 56% male, 44% female
Ethnicity: IG: 23% BME, CG: 20% BME
SES: 73% IG, 61% CG in non-private housing; 39% and 35% in workless households |
| Intervention details | Description: YPDP
Targeted/universal: targeted
Target population: universal targeting of young people
Provider(s): youth service providers
Theory: youth development model
Training: training of volunteers on programme requirements, recognising child abuse, working with youth; monthly supervision
Setting: community youth services
Content: activities focusing on young people’s health and education as well as their broader social development with specific programme content determined by the individual projects delivering services. These could include: education (literacy, numeracy, IT, vocational skills). training/employment opportunities life skills (e.g. communication, decision-making, goal-setting, relationships, negotiation, anger-management), mentoring (weekly one-to-one sessions with staff), volunteering (both career-oriented and community-based), health education (particularly sexual health, substance misuse) arts and sports, advice on accessing services (health, contraceptive, drug and alcohol services, welfare, benefits advice, counselling and advice, housing)
Length/intensity: 6–10 hours’ weekly provision for 1 year
Control: matched comparison |
| Outcomes | Post intervention (9-month follow-up, less than unity favours intervention):
Cannabis use weekly or more in previous 6 months: OR 1.41, 95% CI 0.75 to 1.71
Cannabis use monthly or more in previous 6 months: OR 1.56, 95% CI 0.93 to 2.63
Drunkenness monthly or more in previous 6 months: OR 0.98, 95% CI 0.65 to 1.47
9 months post intervention (18-month follow-up, less than unity favours intervention):
Cannabis use weekly or more often in previous 6 months: OR 1.97 95% CI 0.93 to 4.17
Drunkenness monthly or more often in previous 6 months: OR 1.20 95% CI 0.78 to 1.84 |
| Risk of bias |
|---|
| Item | Author judgement | Description |
| Sequence generation: was the allocation sequence adequately generated? | Not applicable | Non-randomised trial |
| Allocation concealment: was the allocation adequately concealed? | Not applicable | Non-randomised trial |
| Blinding: was knowledge of the allocation intervention adequately prevented during the study? | No | Non-randomised trial |
| Incomplete outcome data: were complete data for each outcome reported and, if not, were adequate reasons for incomplete outcome data provided? | Yes | Weighted analysis partially accounts for missingness |
| Selective outcome reporting: were the findings of the study subject to selective outcome reporting? | Yes | Full outcomes presented at follow-up 1 not presented at follow-up 2 |
| Key confounders: were differences in non-random studies in key confounders (e.g. SES, sex, age) adequately controlled for? | Yes | Covariates included in model |
| Clustering: was clustering of participants accounted for in the analysis? | Yes | Analysis accounted for clustering |
| Other source of bias: were there any other sources of bias that might affect the results of the study? | No | |
