Characteristics and effect sizes of studies included in the meta-analysis
| Author, year | Data collection year | Country | Sample size | Sample age | Outlet density buffer distance (km) | Controls | Outlet density measure* | Distribution of outlet density† | OR (95% CI)‡ |
| Homes | |||||||||
| Novak et al, 200616 | 1995–1999 | USA | 2116 | 11–23§ | 0.43¶ | Minor status, age, race/ethnicity, gender, parental education, commercial land use, neighbourhood racial composition and neighbourhood poverty | Trend | M=7.1 | 1.21 (1.04 to 1.40) |
| Adachi-Mejia et al, 201222 | 2007 | USA | 1263 | 13–18 | 0.80 | Age, race/ethnicity, socioeconomic status, sibling smoking, friend smoking, exposure to movie smoking, team sport participation, sensation seeking, tobacco outlet proximity, and proportion of community population Black, Hispanic and families with income below the poverty level | Trend | Median=0.34 | 1.11 (0.70 to 1.79) |
| Lipperman-Kreda et al, 201414 | 2010 | USA | 832 | 13–18 | 1.21 | Gender, race/ethnicity, age, population density, median family income, and city % of minors <18 years, % African– Americans, % Hispanic, % college-educated and % unemployed | Trend | M=3.88 SD=5.24 Range=0–37.20 | 1.08 (1.01 to 1.16) |
| Shortt et al, 201618 | 2010 | Scotland | 20 446 | 13–15 | 0.80 | Age group, sex, ethnicity, received free school meals, perceived family wealth, family structure, parental smoking status, rurality and Carstairs Deprivation Score | Trend | Range=0 to >5.63 | 1.06 (1.00 to 1.12) |
| Schools | |||||||||
| Leatherdale and Strath, 20071 | 2001–2002 | Canada | 19 464 | 14–18 | 1.00 | Gender, age, parent smoking, older sibling smoking, ever smoked with family member, five closest friends smoking and school student smoking rate | Trend | M=6.3 Range=1–13 | 1.01 (0.99 to 1.03) |
| McCarthy et al, 200915 | 2003–2004 | USA | 19 306 | M=14.9 | 1.61 | Age, gender, race/ethnicity, English-language use in the home, grades, peer smoking, friends’ smoking, ease of obtaining cigarettes, depressive symptoms, school type, school rurality and school-level parental education | Trend | M=10.8 SD=8.9 | 1.11 (1.02 to 1.21) |
| Chan and Leatherdale, 201113 | 2005–2006 | Canada | 22 764 | 9–12 grade | 1.00 | Grade, gender, older sibling smoking, parent smoking, up to five closest friends smoking and neighbourhood disadvantage | Trend | M=2.68 Range=0–16 | 0.99 (0.97 to 1.01) |
| Adams et al, 201319 | 2002 | USA | 9704 | 7–10 grade | 0.80 | Sex, race/ethnicity, grade, illegal tobacco sales rate, median neighbourhood income and mean neighbourhood density | Trend | M=2.76 SD=2.45 Range=0–9 | 1.04 (0.95 to 1.14) |
| Scully et al, 201320 | 2008 | Australia | 2044 | 12–17 | 0.50 | Age, sex, personal spending money, perceived ease of buying cigarettes, smoking status of parents/caretakers and neighbourhood SES | Trend | M=2.37 SD=1.65 Range=0–7 | 1.06 (0.90 to 1.25) |
| Lipperman-Kreda et al, 201414 | 2010 | USA | 832 | 13–18 | 1.21 | Gender, race/ethnicity, age, population density, median family income, and city % of minors <18 years, % African– Americans, % Hispanic, % college-educated, % unemployed | Trend | M=4.97 SD=5.45 Range=0–44.62 | 1.02 (0.93 to 1.11) |
| Mistry et al, 201523 | 2010 | India | 1320 | 8–10 grade | 0.50 | Age, gender, religion, monthly receipt of pocket money, hopelessness, ease of access to tobacco, parental tobacco use, peer tobacco use and school annual fee | Low vs high density | M=60.0 SD=43.9 Range=2–199 | 1.99 (0.92 to 4.33)** |
| Marsh et al, 20163 | 2012 | New Zealand | 27 238 | 14–15 | 1.00 | Sex, age, ethnicity, family smoking, peer smoking, school decile and school location | Zero vs high density | Median=2 | 0.94 (0.82 to 1.07) |
| Shortt et al, 201618 | 2010 | Scotland | 20 446 | 13–15 | 0.80 | Age group, sex, ethnicity, received free school meals, perceived family wealth, family structure, parental smoking status, rurality and Carstairs Deprivation Score | Trend | Range=0 to >6.72 | 0.98 (0.92 to 1.04) |
*This column represents how the number of tobacco outlets was measured. Most studies used a count measure in which higher scores indicated a greater number of outlets (trend). Some studies compared zero/low vs high density areas.
†These values represent descriptive statistics of tobacco outlet density provided in each study. These values may not be directly comparable due to differences in density and buffer size conceptualisations. Please refer to the ‘Outlet Density Buffer Distance’ and ‘Outlet Density Measure’ columns for more information about how to interpret these values.
‡These values represent adjusted ORs by the controls listed in the ‘Controls’ column.
§Although the age range extended beyond our initial cut-off of 18 years old, the legal age to purchase cigarettes did not significantly influence the association between tobacco outlet density and current smoking.
¶We calculated the average census tract distance from the city in which the study was conducted to represent the outlet density catchment distance.
**This study outcome included both smoked and non-smoked tobacco products.