Table 2

Separate meta-analyses by study characteristics estimating relative risk reduction (RRR) in tobacco use from reduction of tobacco retailer density and proximity, k=285, n=27

CharacteristicsnkI2Estimated RRR (95% CI)
Outcome variable
 All behavioural outcomes2625599.822.48 (1.95 to 3.02)
  Smoking106899.922.06 (1.26 to 2.85)
  Quitting (reverse coded)1512599.756.50 (4.64 to 8.37)
  Relapse3120−0.04 (−0.24 to 0.17)
  Young adult initiation3190−0.25 (−1.09 to 0.60)
  Other (eg, stage of change)53199.723.28 (1.54 to 5.02)
 Health outcomes23041.840.01 (−0.01 to 0.03)
Predictor variable*
 Proximity (reverse coded)1410087.882.38 (1.39 to 3.37)
 Density—all types2415599.892.55 (1.91 to 3.19)
  Count85399.995.29 (2.49 to 8.10)
  Per land area104599.943.30 (2.19 to 4.42)
  Per persons1600.07 (−0.88 to 1.03)
  Other (eg, proportion of smaller area units within area unit with retailers)65174.853.84 (2.24 to 5.44)
Design and statistics*
Use of activity space21233.0119.85 (12.44 to 27.26)
Longitudinal109699.804.91 (3.03 to 6.79)
Cross-sectional1815999.832.22 (1.65 to 2.79)
 Adjustment for confounders or covariates
  Adjusted: no controls (unadjusted)10730−0.01 (−0.03 to 0.01)
  Adjusted: individual characteristics only138999.814.04 (2.95 to 5.14)
  Adjusted: neighbourhood characteristics only22
  Adjusted: both individual and neighbourhood characteristics149196.452.96 (1.70 to 4.23)
 No delinearisation of predictor15813.56−0.0003 (−0.02 to 0.02)
 Used delinearisation of predictor1617477.894.33 (3.32 to 5.33)
 Used ordinal or nominal outcome variable32400.15 (−0.25 to 0.56)
 No ordinal or nominal outcome variable2323199.872.87 (2.25 to 3.50)
 Results with men and women combined2421599.772.04 (1.57 to 2.50)
  Women-specific effect sizes32268.990.17 (−4.25 to 4.58)
  Men-specific effect sizes21853.6515.30 (8.28 to 22.31)
 Results with incomes combined2624499.832.59 (2.04 to 3.14)
  Low income-specific effect sizes2536.724.31 (0.19 to 8.43)
  High income-specific effect sizes2632.04−1.01 (−2.48 to 0.46)
 Aggregated tobacco use intensity2522399.812.39 (1.88 to 2.90)
  Low intensity11628.63−2.61 (−6.94 to 1.72)
  High intensity11673.227.84 (−1.09 to 16.77)
Context*
 Country
  Australia21637.790.001 (−0.03 to 0.04)
  Canada1010499.143.10 (2.06 to 4.14)
  Finland25491.845.84 (2.06 to 9.62)
  New Zealand11216.391.28 (0.15 to 2.40)
  UK42291.604.48 (2.97 to 5.98)
  USA84799.821.61 (0.72 to 2.49)
 Retail point-of-sale advertising†
  Without retail advertising restrictions1413799.932.86 (2.04 to 3.69)
  With retail advertising restrictions1211886.000.86 (0.49 to 1.24)
 Retail display of tobacco products‡
  Without retail display restrictions1715599.872.32 (1.68 to 2.96)
  With retail display restrictions910099.413.80 (2.60 to 5.00)
  • Each row represents a separate meta-analysis of the effect sizes in that row; n is the number of studies include and k is the number of effect sizes included. I2 is a measure of heterogeneity. Bold indicates a statistically significant estimate at the historical p<0.05 threshold. We suppressed results with fewer than five effect sizes.

  • *Includes only behavioural effect sizes (k=255).

  • †Presence of an advertising policy includes results from Australia, Canada and New Zealand.

  • ‡Presence of a display policy includes only results from Canada.

  • NR, not reported.