Inclusion criteria definitions of each group
| Group | Definition |
|---|---|
| Low SES | Because definitions of low SES vary across high-income countries this study used an inclusive definition of low SES. Studies were included if they described participants as being low SES and gave at least one measure of SES. This measure could be income (above/below poverty level); address in deprived neighbourhood, etc |
| Indigenous groups | The following definition was used to define potential Indigenous studies in accordance with previous studies:39 “the experiences shared by a group of people who have inhabited a country for thousands of years, which often contrast with those of other groups residing in the same country for a few hundred years”40 |
| Mental illness | People with a mental illness were defined as individuals who had been diagnosed with a mental illness, severe mental illness or were described as inpatients or outpatients in a mental health rehabilitation facility. Substance use disorders were also included. All mental illnesses were included |
| At-risk youth | At-risk youth were defined as individuals under the age of 21 who have experienced or are experiencing: problems at school; physical, sexual or psychological abuse; mental or physical health problems; economic disadvantage; or who have committed a violent or delinquent act (USA Code36) |
| Prisoners | Prisoners included those currently incarcerated and also ex-prisoners living in the community |
| Homeless | Homeless individuals were defined as those individuals described as meeting national criteria for homelessness or those individuals accessing services provided to homeless persons |
| Smoker | Smokers were defined as self-reported daily or occasional cigarette smokers. Studies that also assessed ex-smokers were only included if the majority of participants were current smokers, or if the results were reported by smoking status. Studies were excluded if they focused solely on ex-smokers or non-smokers |
SES, socioeconomic status.