Publicação
Evaluating the outcomes and the impact of substance use prevention interventions
| Resumo: | Theoretical framework: Substance use among adolescents is a major cause of concern as it can compromise adolescents’ health, defined in 1948 by the World Health Organization (WHO) as “a state of complete physical, mental, and social well-being” and may hinder adolescents from achieving the developmental transitions they are supposed to accomplish. Further, when individuals initiate substance use as adolescents, addiction is established more easily and quickly (Crews, He, & Hodge, 2007; Prokhorov et al., 2006) and individuals remain at greater risk for negative outcomes in the future even if they successfully stop using (Georgiades & Boyle, 2007; Meier et al., 2012; von Sydow, Lieb, Pfister, Höfler, & Wittchen, 2002). With substance use being a preventable behaviour, prevention interventions have been implemented worldwide, mostly focused on demand reduction (Kulis, Nieri, Yabiku, Stromwall, & Marsiglia, 2007) and aimed at achieving some form of abstinence (Midford, 2009). Over recent years, efforts to determine whether prevention interventions are effective have increased due to the growing demand for accountability of interventions in public health (Hillebrand & Burkhart, 2009). Programme evaluation, besides considering the positive and desirable effects from prevention interventions, should also taken into consideration its negative and undesirable effects (i.e. iatrogenic effects) (European Monitoring Centre for Drugs and Drug Addiction (EMCDDA, 2012a). Programme evaluation is the mechanism through which this judgment on efficacy can be made (Midford, 2000), and is an essential tool to enable policy makers and practitioners to decide which projects to fund and whether a particular intervention is worth continuing, adapting, or discarding (EMCDDA, 2012a). However, in Europe, despite prevention interventions now being systematically monitored by the majority of Member States (EMCDDA, 2009a), prevention effectiveness remains poorly researched (EMCDDA, 2010) and very few prevention interventions have actually been evaluated (EMCDDA, 2012b). Thus, evaluation of prevention interventions is urgently required to increase knowledge about how to enhance their intended effects and decrease the unintended, which in turn will contribute to future prevention interventions’ success in reducing the prevalence of substance use among adolescents. Aims and objectives: The main aim of this research is to evaluate the outcomes of substance use prevention interventions among a sample of vulnerable Portuguese adolescents. The research consists of two related studies: Study 1 aimed to (a) examine substance use patterns; (b) identify proximal, distal, and ultimal variables associated with substance use; (c) determine the differential effect of these variables on substance use; and (d) recognize risk and protective factors for substance use; and study 2 aimed to (a) assess the effects of preventive interventions on variables associated with substance use; (b) evaluate interventions' effects on substance use itself; (c) determine which prevention approaches are effective in changing risk factors for substance use; and (d) examine any iatrogenic effects associated with prevention interventions. Method: Participants were vulnerable Portuguese adolescents aged between 12 and 18 years old participating in substance use prevention interventions in Portugal (hereinafter designated as cases) and a control group of adolescents not participating in such programmes (hereinafter designated as controls). Cases completed a structured questionnaire on substance use behaviours and related variables prior to their participation in a prevention programme (i.e., pre-test), during the intervention (i.e., intermediate-test), after the intervention (i.e., post-test), and at six and 12 months follow-up (i.e., follow-up 1 and follow-up 2 respectively). Control students completed the questionnaires at equivalent time periods. Study 1 used a crosssectional research design including 2.581 cases completing pre-test questionnaires. These data were analysed to identify factors associated with substance use, and these factors were used as outcome measurements in study 2. From the study 1 sample, 1.756 adolescents formed the experimental group and an additional 375 adolescents not participating in such programmes constituted the control group. Study 2 used a quasi-experimental research design using data from five time points to examine any changes in substance use and related variables. Results: Results from this research revealed that, among the sample of vulnerable adolescents assessed, alcohol was considered the least harmful substance; the substance leading to less problems and more benefits; the substance towards which adolescents hold more positive and neutral attitudes; the most consumed substance among best friends; the substance perceived as most accessible; and the substance towards which parents were least expected to prohibit. These findings indicated that alcohol consumption is widespread among adolescents and perceived as socially accepted, framing the fact that alcohol was the substance which most adolescents express an intention to use. As for prevention interventions, the study found no evidence that they were effective in changing any of the variables associated with drinking. Further, there was evidence that prevention interventions seem to have lead vulnerable adolescents to perceive drinking as less risky along with a increase on drinking level among these adolescents. Regarding smoking, tobacco was found to be the substance with the highest percentage of consumers becoming regular users and, after alcohol, the substance which adolescents most expressed intention to use. There was evidence that prevention interventions significantly reduced positive attitudes towards smoking, smoking level, and best friends' smoking behaviour. However, there was also evidence that prevention interventions were associated with an increase in the expected benefits from smoking. For cannabis, there was evidence that the percentage of adolescents holding positive attitudes towards cannabis was higher than for tobacco and very similar as for alcohol; that adolescents use cannabis despite holding negative attitudes and not expecting benefits from use; and that adolescents consider using cannabis to be less harmful than smoking tobacco. There was no evidence that prevention interventions were effective in changing any of the variables associated with cannabis use assessed in this research. Further, there was evidence that prevention interventions were associated with an increase in expect benefits from cannabis use. Data on cocaine demonstrates that it was considered the most harmful substance and the substance for which most adolescents expected problems and least expect benefits from use, framing the fact that cocaine was the substance that least adolescents expressed intention to use. Data suggested that prevention interventions were not effective in changing any of the variables associated with cocaine use assessed in this research. Further, there was evidence that prevention interventions were associated with an increase in intention to use cocaine among vulnerable adolescents. Conclusions: Overall, this research has shown that prevention interventions have not produced statistically significant changes in most of the variables associated with vulnerable adolescents' substance use. Although some positive effects were found, prevention interventions led to more negative and even iatrogenic outcomes than positive and effective outcomes. Recommendations: This research presents recommendations for practice regarding the most suitable target age for prevention interventions with vulnerable adolescents, the contents of prevention packages, as well as specific socio-demographic features that should be considered when designing prevention interventions for vulnerable adolescents. Questions for further research are also presented. |
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| Autores principais: | Santos, Elisabete Rute, 1979- |
| Assunto: | Consumo de substâncias Avaliação de programas Adolescentes - Psicologia Teses de doutoramento (co-tutela) - 2014 |
| Ano: | 2014 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Theoretical framework: Substance use among adolescents is a major cause of concern as it can compromise adolescents’ health, defined in 1948 by the World Health Organization (WHO) as “a state of complete physical, mental, and social well-being” and may hinder adolescents from achieving the developmental transitions they are supposed to accomplish. Further, when individuals initiate substance use as adolescents, addiction is established more easily and quickly (Crews, He, & Hodge, 2007; Prokhorov et al., 2006) and individuals remain at greater risk for negative outcomes in the future even if they successfully stop using (Georgiades & Boyle, 2007; Meier et al., 2012; von Sydow, Lieb, Pfister, Höfler, & Wittchen, 2002). With substance use being a preventable behaviour, prevention interventions have been implemented worldwide, mostly focused on demand reduction (Kulis, Nieri, Yabiku, Stromwall, & Marsiglia, 2007) and aimed at achieving some form of abstinence (Midford, 2009). Over recent years, efforts to determine whether prevention interventions are effective have increased due to the growing demand for accountability of interventions in public health (Hillebrand & Burkhart, 2009). Programme evaluation, besides considering the positive and desirable effects from prevention interventions, should also taken into consideration its negative and undesirable effects (i.e. iatrogenic effects) (European Monitoring Centre for Drugs and Drug Addiction (EMCDDA, 2012a). Programme evaluation is the mechanism through which this judgment on efficacy can be made (Midford, 2000), and is an essential tool to enable policy makers and practitioners to decide which projects to fund and whether a particular intervention is worth continuing, adapting, or discarding (EMCDDA, 2012a). However, in Europe, despite prevention interventions now being systematically monitored by the majority of Member States (EMCDDA, 2009a), prevention effectiveness remains poorly researched (EMCDDA, 2010) and very few prevention interventions have actually been evaluated (EMCDDA, 2012b). Thus, evaluation of prevention interventions is urgently required to increase knowledge about how to enhance their intended effects and decrease the unintended, which in turn will contribute to future prevention interventions’ success in reducing the prevalence of substance use among adolescents. Aims and objectives: The main aim of this research is to evaluate the outcomes of substance use prevention interventions among a sample of vulnerable Portuguese adolescents. The research consists of two related studies: Study 1 aimed to (a) examine substance use patterns; (b) identify proximal, distal, and ultimal variables associated with substance use; (c) determine the differential effect of these variables on substance use; and (d) recognize risk and protective factors for substance use; and study 2 aimed to (a) assess the effects of preventive interventions on variables associated with substance use; (b) evaluate interventions' effects on substance use itself; (c) determine which prevention approaches are effective in changing risk factors for substance use; and (d) examine any iatrogenic effects associated with prevention interventions. Method: Participants were vulnerable Portuguese adolescents aged between 12 and 18 years old participating in substance use prevention interventions in Portugal (hereinafter designated as cases) and a control group of adolescents not participating in such programmes (hereinafter designated as controls). Cases completed a structured questionnaire on substance use behaviours and related variables prior to their participation in a prevention programme (i.e., pre-test), during the intervention (i.e., intermediate-test), after the intervention (i.e., post-test), and at six and 12 months follow-up (i.e., follow-up 1 and follow-up 2 respectively). Control students completed the questionnaires at equivalent time periods. Study 1 used a crosssectional research design including 2.581 cases completing pre-test questionnaires. These data were analysed to identify factors associated with substance use, and these factors were used as outcome measurements in study 2. From the study 1 sample, 1.756 adolescents formed the experimental group and an additional 375 adolescents not participating in such programmes constituted the control group. Study 2 used a quasi-experimental research design using data from five time points to examine any changes in substance use and related variables. Results: Results from this research revealed that, among the sample of vulnerable adolescents assessed, alcohol was considered the least harmful substance; the substance leading to less problems and more benefits; the substance towards which adolescents hold more positive and neutral attitudes; the most consumed substance among best friends; the substance perceived as most accessible; and the substance towards which parents were least expected to prohibit. These findings indicated that alcohol consumption is widespread among adolescents and perceived as socially accepted, framing the fact that alcohol was the substance which most adolescents express an intention to use. As for prevention interventions, the study found no evidence that they were effective in changing any of the variables associated with drinking. Further, there was evidence that prevention interventions seem to have lead vulnerable adolescents to perceive drinking as less risky along with a increase on drinking level among these adolescents. Regarding smoking, tobacco was found to be the substance with the highest percentage of consumers becoming regular users and, after alcohol, the substance which adolescents most expressed intention to use. There was evidence that prevention interventions significantly reduced positive attitudes towards smoking, smoking level, and best friends' smoking behaviour. However, there was also evidence that prevention interventions were associated with an increase in the expected benefits from smoking. For cannabis, there was evidence that the percentage of adolescents holding positive attitudes towards cannabis was higher than for tobacco and very similar as for alcohol; that adolescents use cannabis despite holding negative attitudes and not expecting benefits from use; and that adolescents consider using cannabis to be less harmful than smoking tobacco. There was no evidence that prevention interventions were effective in changing any of the variables associated with cannabis use assessed in this research. Further, there was evidence that prevention interventions were associated with an increase in expect benefits from cannabis use. Data on cocaine demonstrates that it was considered the most harmful substance and the substance for which most adolescents expected problems and least expect benefits from use, framing the fact that cocaine was the substance that least adolescents expressed intention to use. Data suggested that prevention interventions were not effective in changing any of the variables associated with cocaine use assessed in this research. Further, there was evidence that prevention interventions were associated with an increase in intention to use cocaine among vulnerable adolescents. Conclusions: Overall, this research has shown that prevention interventions have not produced statistically significant changes in most of the variables associated with vulnerable adolescents' substance use. Although some positive effects were found, prevention interventions led to more negative and even iatrogenic outcomes than positive and effective outcomes. Recommendations: This research presents recommendations for practice regarding the most suitable target age for prevention interventions with vulnerable adolescents, the contents of prevention packages, as well as specific socio-demographic features that should be considered when designing prevention interventions for vulnerable adolescents. Questions for further research are also presented. |
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