Equity effects of children’s physical activity interventions: a systematic scoping review

BACKGROUND: Differential effects of physical activity (PA) interventions across population sub-groups may contribute to inequalities in health. This systematic scoping review explored the state of the evidence on equity effects in response to interventions targeting children’s PA promotion. The aims were to assess and summarise the availability of evidence on differential intervention effects of children’s PA interventions across gender, body mass index, socioeconomic status, ethnicity, place of residence and religion. METHODS: Using a pre-piloted search strategy, six electronic databases were searched for controlled intervention trials, aiming to increase PA in children (6–18 years of age), that used objective forms of measurement. Screening and data extraction were conducted in duplicate. Reporting of analyses of differential effects were summarized for each equity characteristic and logistic regression analyses run to investigate intervention characteristics associated with the reporting of equity analyses. RESULTS: The literature search identified 13,052 publications and 7963 unique records. Following a duplicate screening process 125 publications representing 113 unique intervention trials were included. Although the majority of trials collected equity characteristics at baseline, few reported differential effects analyses across the equity factors of interest. All 113 included interventions reported gender at baseline with 46% of non-gender targeted interventions reporting differential effect analyses by gender. Respective figures were considerably smaller for body mass index, socioeconomic status, ethnicity, place of residence and religion. There was an increased likelihood of studying differential effects in school based interventions (OR: 2.9 [1.2–7.2]) in comparison to interventions in other settings, larger studies (per increase in 100 participants; 1.2 [1.0 – 1.4]); and where a main intervention effect on objectively measured PA was reported (3.0 [1.3–6.8]). CONCLUSIONS: Despite regularly collecting relevant information at baseline, most controlled trials of PA interventions in children do not report analyses of differences in intervention effect across outlined equity characteristics. Consequently, there is a scarcity of evidence concerning the equity effects of these interventions, particularly beyond gender, and a lack of understanding of subgroups that may benefit from, or be disadvantaged by, current intervention efforts. Further evidence synthesis and primary research is needed to effectively understand the impact of PA interventions on existing behavioural inequalities within population subgroups of children. TRIAL REGISTRATION: PROSPERO (PROSPERO 2016: CRD42016034020). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12966-017-0586-8) contains supplementary material, which is available to authorized users.