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Table 4 Random-effects meta-analysis results of uncontrolled before-and-after studies

From: A systematic review and meta-analysis of the effectiveness of food safety education interventions for consumers in developed countries

Meta-analysis sub-groupa No. participants/trials/studiesb No. (%) trials with combined outcome measuresc Effect measured Effect estimate average (95 % CI)M/median (range)R,e I 2
Educational training/courses
 Educators-Behaviours 85/2/2 1 (50) SMD 0.44 (0.33, 0.54)M 0 %
 Educators-Knowledge 47/3/3 2 (67) RR 2.86 (1.31, 5.63)R 79 %
 Educators-Attitudes 33/2/2 0 (0) RR 1.34 (1.06, 1.63)R 73 %
 Adults-Behaviours 11,764/17/16 8 (47) SMD 0.28 (0.11, 1.49)R 100 %
 Adults-Behaviours 3049/10/10 7 (70) RR 1.26 (0.95, 2.66)R 97 %
 Adults-Knowledgef 1018/8/7 0 (0) SMD 0.61 (0.01, 1.04)R 95 %
 Adults-Knowledge 4239/6/6 1 (17) RR 1.92 (1.18, 3.10)R 99 %
 Adults-Attitudesf 1332/7/7 3 (43) SMD 0.43 (0.05, 0.95)R 99 %
 Adults-Attitudes 876/4/4 1 (25) RR 1.09 (1.04, 1.33)R 86 %
 Children/youth-Behaviours 401/3/3 0 (0) SMD 0.31 (0.14, 1.32)R 99 %
 Children/youth-Behaviours 226/2/2 1 (50) RR 5.37 (1.04, 9.69)R 94 %
 Children/youth-Knowledge 1028/6/6 1 (17) SMD 1.06 (0.09, 4.02)R 100 %
 Children/youth-Knowledge 1719/6/6 4 (67) RR 1.77 (1.11, 5.04)R 98 %
 Children/youth-Attitudes 294/3/3 0 (0) SMD 0.31 (0.10, 1.32)R 99 %
Media campaigns/other messaging
 Adults-Behaviours 2430/7/6 5 (71) RR 1.35 (0.90, 2.35)R 93 %
 Adults-Knowledge 1129/7/7 7 (100) RR 1.58 (1.07, 1.87)R 96 %
 Adults-Attitudesf 1002/3/3 1 (33) SMD 0.43 (0.13, 0.81)R 99 %
 Adults-Attitudes 2420/6/5 2 (33) RR 1.10 (1.02, 1.23)R 85 %
 Adults-Stages of changeg 1193/3/2 0 (0) RR 1.09 (1.07, 1.81)R 70 %
  1. SMD standardized mean difference (Hedges’ g), RR relative risk, CI confidence interval
  2. aSubgroups divided by intervention type, target population, and outcome type. Note that all outcomes in this table had a GRADE rating of very low (the true effect is likely to be substantially different from the measured estimate)
  3. bFor trials with a RR outcome, the number of participants in this column refers to the number in the post intervention group
  4. cRefers to studies that reported multiple measures of the same construct in the same individuals, which were combined post hoc into one overall measure
  5. dNote that all trials in SMD analyses used imputed values for pre-post correlations of 0.81 for knowledge and attitude outcomes from Medeiros et al. (2004) [36] or 0.83 for behaviour outcomes from Kendall et al. (2004) [37]
  6. eSuperscript M indicates that an average estimate of effect and 95 % CI is provided because heterogeneity was low to moderate (I2 = 0–60 %). Superscript R indicates that the median and range of study effect sizes is provided because heterogeneity was high (I2 > 60 %)
  7. fSensitivity analyses for these outcomes revealed that the selection of the imputed correlation value had an appreciable impact on the meta-analysis results (Additional file 12), leading to a downgrading of these findings in the GRADE assessment (Additional file 10)
  8. gRR for this outcome refers to the impact of the intervention to change participants’ stage from contemplation/pre-contemplation/preparation to action/maintenance [32]