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

Table 3 Random-effects meta-analysis results of randomized and non-randomized controlled trials

Meta-analysis sub-group^a	No. participants/trials/studies	No. (%) trials with combined outcome measures^b	Effect measure	Effect estimate average (95 % CI)^M/median (range)^R,c	I ²	GRADE^d
RCT
Educational training/courses
Adults-Behaviours^e	709/4/4	2 (50)	SMD	0.68 (−0.06, 1.41)^R	94 %	Low
Adults-Knowledge	596/3/3	0 (0)	SMD	0.87 (−0.05, 1.29)^R	93 %	Very low
Children/youth-Behaviours	6379/2/2	1 (50)	SMD	0.20 (0.05, 0.35)^R	96 %	High
Media campaigns/other messaging
Adults-Behavioural intentions	117/2/2	1 (50)	SMD	0.36 (0.02, 0.69)^M	0 %	Moderate
Adults-Behaviours	686/4/4	1 (25)	SMD	0.24 (−0.17, 1.03)^R	85 %	Low
Adults-Knowledge	528/3/3	0 (0)	SMD	0.42 (0.03, 0.92)^R	82 %	Low
Adults-Attitudes	4914/8/8	4 (50)	SMD	0.34 (0.05, 0.76)^R	94 %	Low
NRT
Educational training/courses
Adults-Behaviours^e	1099/4/2	0 (0)	SMD	0.37 (0.08, 0.66)^M	58 %	Low
Adults-Knowledge	1356/5/3	0 (0)	SMD	0.44 (0.12, 1.14)^R	82 %	Low
Adults-Attitudes	778/4/2	1 (25)	SMD	0.26 (0.10, 0.43)^M	0 %	Moderate
Children/youth-Behaviours	329/3/2	0 (0)	SMD	0.33 (0.17, 0.90)^R	64 %	Very low
Children/youth-Knowledge	339/3/2	0 (0)	SMD	0.24 (0.14, 0.73)^R	75 %	Very low
Media campaigns/other messaging
Adults-Behaviours	1118/2/2	0 (0)	RR	2.31 (1.30, 3.33)^R	90 %	Low
Adults-Attitudes	1442/3/3	1 (33)	RR	1.75 (1.01, 2.85)^R	95 %	Very low

RCT randomized controlled trials, NRT non–randomized controlled trials, SMD standardized mean difference (Hedges’ g), RR relative risk, CI confidence interval
^aSubgroups divided by study design, intervention type, target population, and outcome type
^bRefers to studies that reported multiple measures of the same construct in the same individuals, which were combined post hoc into one overall measure
^cSuperscript ^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 %)
^dExplanation of the GRADE ratings:
Very low = the true effect is likely to be substantially different from the measured estimate
Low = the true effect may be substantially different from the measured estimate
Moderate = the true effect is likely to be close to the measured estimate, but there is a possibility that it is substantially different
High = strong confidence that the true effect lies close to that of the measured estimate
^eOne trial/study in each of these analyses used an imputed pre-post correlation value of 0.83 from Kendall et al. (2004) [37]. In both cases, sensitivity analyses indicated that the selection of the imputed 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)

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