Parent-focused behavioural interventions for the prevention of early childhood obesity (TOPCHILD): a systematic review and individual participant data meta-analysis

Background: Childhood obesity is a global public health issue, which has prompted governments to invest in prevention programmes. We aimed to investigate the effectiveness of parent-focused early childhood obesity prevention interventions globally. Methods: We did a systematic review and individual participant data meta-analysis. We searched databases and trial registries (MEDLINE, Embase, CENTRAL, CINAHL, PsycInfo, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform) from inception until Sept 30, 2024, for randomised controlled trials commencing before 12 months of age examining parent-focused behavioural interventions to prevent obesity in children, compared with usual care, no intervention, or attention control. Individual participant data were checked, harmonised, and assessed for integrity and risk of bias. We excluded trials that were quasi-randomised, investigated pregnancy-only interventions, or did not collect any child weight-related outcomes. The primary outcome was BMI Z score at age 24 months (±6 months). We did an intention-to-treat, two-stage, random effects meta-analysis to examine effects overall and for prespecified subgroups. We assessed certainty of evidence using Grading of Recommendations Assessment, Development, and Evaluation. This study is registered with PROSPERO, CRD42020177408. Findings: Of 19 990 identified records, 47 (0·24%) trials were completed and eligible. Of these, 18 (38%) assessed our primary outcome, BMI Z score. We obtained individual participant data for 17 (94%; n=9128) of these 18 trials (n=9383), representing 97% of eligible participants. Of these 9128 participants, 4549 (50%) were boys, 4415 (48%) were girls, and 164 (2%) had unknown sex. We found no evidence of an effect of interventions on BMI Z score at age 24 months (±6 months; mean difference –0·01 [95% CI –0·08 to 0·05]; high certainty evidence, τ²=0·01; n=6505; 2623 missing). Findings were robust to prespecified sensitivity analyses (eg, different analysis methods and missing data), and we found no evidence of differential intervention effects for prespecified subgroups including priority populations and trial-level factors. Interpretation: These findings indicate that examined parent-focused behavioural interventions are insufficient to prevent obesity at age 24 months (±6 months). This evidence highlights a need to re-think childhood obesity prevention approaches. Funding: Australian National Health and Medical Research Council.