Tobacco Control Interventions – Design Trade-Offs K. S. (Steve) Brown Department of Statistics and Actuarial Science Health Behaviour Research Group University of Waterloo

What is the Intervention? Comprehensive mix of policies and programs is thought to be most effective way to reduce tobacco use with youth (CDCP, 1999). Comprehensive mix of policies and programs is thought to be most effective way to reduce tobacco use with youth (CDCP, 1999). Some evidence that school-based programs work best in conjunction with other efforts (e.g. with media activities, by-laws or part of community-wide intervention). Some evidence that school-based programs work best in conjunction with other efforts (e.g. with media activities, by-laws or part of community-wide intervention). e.g. Florida state-wide intervention emphasized youth leadership in planning and implementing interventions in schools and communities. e.g. Florida state-wide intervention emphasized youth leadership in planning and implementing interventions in schools and communities.

Unlike Trials of Therapeutic Agents….. Many of the tenets of RCT’s do not carry over to community trials Many of the tenets of RCT’s do not carry over to community trials “Intervention” is more than just the agent (e.g. program or policy), but must include provider, setting and context “Intervention” is more than just the agent (e.g. program or policy), but must include provider, setting and context Hard – and not realistic – to try to control these factors (e.g. provider, setting, context) Hard – and not realistic – to try to control these factors (e.g. provider, setting, context)

Intervention Issues Multi-faceted mix of programs and policies Multi-faceted mix of programs and policies Interventions in many settings (schools, stores, media, political jurisdictions) Interventions in many settings (schools, stores, media, political jurisdictions) Interventions need “champion(s)” at the local level Interventions need “champion(s)” at the local level Communities need to be ready to intervene Communities need to be ready to intervene Sustainability of interventions after the research team leaves is an issue Sustainability of interventions after the research team leaves is an issue

Intervention Issues Randomized Trial – communities could pick from menu, but implement several activities simultaneously Randomized Trial – communities could pick from menu, but implement several activities simultaneously Communities must be ready to intervene in more than one area Communities must be ready to intervene in more than one area Hard to attribute “success” to individual components Hard to attribute “success” to individual components

Intervention Issues Multiple Baseline – interventions implemented one-at-a-time in different settings Multiple Baseline – interventions implemented one-at-a-time in different settings Might be more feasible to have communities tackle only one intervention Might be more feasible to have communities tackle only one intervention Assumes effects are additive – dangerous if interactions are present Assumes effects are additive – dangerous if interactions are present Some programs may not work in isolation but may act synergistically with other components Some programs may not work in isolation but may act synergistically with other components

Methodological Issues End-Points End-Points Measures of Smoking, Process variables Measures of Smoking, Process variables Inclusion/Exclusion Criteria Inclusion/Exclusion Criteria Blocking/Stratification Blocking/Stratification Randomization (?) Randomization (?) Blinding Blinding Duration of the study Duration of the study Longitudinal vs. Repeated Cross-Sectional Longitudinal vs. Repeated Cross-Sectional

Intermediate (Surrogate) End-Points Knowledge, beliefs, values, attitudes, intentions Experimentation Regular Smoking (Weekly Daily) Regular Smoking (Adult) Disease and Death

Process End - Points Process variables must be measured to assess intervention components Process variables must be measured to assess intervention components RCT Design assess process and smoking data simultaneously RCT Design assess process and smoking data simultaneously Multiple Baseline Design intervenes in stages. Not all communities need to measure both process and smoking data Multiple Baseline Design intervenes in stages. Not all communities need to measure both process and smoking data

Measures of Smoking, Process Variables Smoking measures depend on self-report Smoking measures depend on self-report Measures of process are essential to monitor community activity Measures of process are essential to monitor community activity Requires measurement of all facets of intervention (e.g. restrictions on sales, enforcement of by-laws, etc.) Requires measurement of all facets of intervention (e.g. restrictions on sales, enforcement of by-laws, etc.)

Measures of Setting and Context Factors Need to find reliable measurement systems for setting and contextual factors such as programs, policies and broader environmental variables Need to find reliable measurement systems for setting and contextual factors such as programs, policies and broader environmental variables Need commitment from communities to continually monitor Need commitment from communities to continually monitor Interesting analysis challenges with variables at level of student, school, community, and larger jurisdictions Interesting analysis challenges with variables at level of student, school, community, and larger jurisdictions

Inclusion/Exclusion Inclusion/exclusion criteria are based on community characteristics Inclusion/exclusion criteria are based on community characteristics Subjects are indirectly recruited Subjects are indirectly recruited Purpose of research/benefits of research not necessarily a priority for the community Purpose of research/benefits of research not necessarily a priority for the community Need willing champions in the communities and researchers willing to work in communities Need willing champions in the communities and researchers willing to work in communities

Blocking/Stratification Matched pairs RCT requires communities to be matched on characteristics related to outcome (e.g. adult smoking rates, SES, etc.) Matched pairs RCT requires communities to be matched on characteristics related to outcome (e.g. adult smoking rates, SES, etc.) Community pairs should include wide variation in expected outcome for generalizability. Community pairs should include wide variation in expected outcome for generalizability. Could include pairs in different countries Could include pairs in different countries

Blocking/Stratification Multiple Baseline design uses each community as its own control and corrects for secular effects with staggered start Multiple Baseline design uses each community as its own control and corrects for secular effects with staggered start Fewer communities in each set could limit generalizability Fewer communities in each set could limit generalizability Could choose communities in different countries Could choose communities in different countries

Randomization Typically at level of community Typically at level of community Allows for replication at the level of implementation Allows for replication at the level of implementation Realistic model of how the intervention would be delivered Realistic model of how the intervention would be delivered RCT does require communities to be willing to be randomized RCT does require communities to be willing to be randomized Multiple baseline could randomize within sets of communities to determine order of intervention Multiple baseline could randomize within sets of communities to determine order of intervention

Blinding “Control” groups are often “Usual Care” – i.e. not feasible to change normal practice for the control communities “Control” groups are often “Usual Care” – i.e. not feasible to change normal practice for the control communities Difficult to “blind” participants, impossible to “blind” providers Difficult to “blind” participants, impossible to “blind” providers Must recognize the “provider” effect Must recognize the “provider” effect Difficult to maintain control communities for long trials Difficult to maintain control communities for long trials Repeated Baseline gives promise of intervention soon to control communities Repeated Baseline gives promise of intervention soon to control communities

Duration of Study Early studies of elementary school based interventions showed differences to the end of Grade 8 that faded by the end of grade 12 without further intervention Early studies of elementary school based interventions showed differences to the end of Grade 8 that faded by the end of grade 12 without further intervention Secular trends can make research findings obsolete Secular trends can make research findings obsolete Important to study end points after the research team has left Important to study end points after the research team has left Need to marry research, evaluation and practice Need to marry research, evaluation and practice

Duration of the Study Multiple Baseline design requires multiple interventions in multiple communities followed by a comprehensive intervention in several communities to verify the results. Multiple Baseline design requires multiple interventions in multiple communities followed by a comprehensive intervention in several communities to verify the results. Some interventions may be of shorter duration depending on target (e.g. retailer program vs school-based curriculum). Some interventions may be of shorter duration depending on target (e.g. retailer program vs school-based curriculum).

Duration of Study RCT requires comprehensive interventions in study communities RCT requires comprehensive interventions in study communities For the same total time, the comprehensive intervention could be conducted for a longer time with the RCT For the same total time, the comprehensive intervention could be conducted for a longer time with the RCT Both designs require sufficient lead time to bring the communities “on board” Both designs require sufficient lead time to bring the communities “on board” Both designs require follow-up to assess sustainability Both designs require follow-up to assess sustainability

Longitudinal vs Cross-Sectional Data Both designs allow for either longitudinal data or repeated cross-sectional data on either individuals or process variables Both designs allow for either longitudinal data or repeated cross-sectional data on either individuals or process variables Repeated cross-sectional data could be available on adolescent smoking rates from existing surveys, but generally insufficient sample sizes would be obtained for smaller communities Repeated cross-sectional data could be available on adolescent smoking rates from existing surveys, but generally insufficient sample sizes would be obtained for smaller communities