Importance: There is a gap in the evidence regarding nature-based interventions (NBIs) for children with autism spectrum disorder (ASD).
Objective: To systematically review and meta-analyze available evidence on the health-related outcomes in NBIs for children with ASD.
Data sources: The Cumulative Index to Nursing and Allied Health Literature, Cochrane, Embase, Emcare, Education Resources Information Center, Global Health, MEDLINE, PsycInfo, SPORTDiscus, and Web of Science were searched from inception until May 2023. Google Scholar and references from included studies were searched for additional studies.
Study selection: Included studies were randomized clinical trials (RCTs), controlled studies, and single-group before-and-after studies that reported health-related outcomes.
Data extraction and synthesis: This review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) reporting guidelines. Random-effects meta-analyses were used to synthesize the data. The findings of studies that were ineligible for meta-analysis were summarized according to the Synthesis Without Meta-analysis (SWIM) reporting guidelines.
Main outcomes and measures: The outcomes of interest were health-related outcomes (ie, social functioning, behavioral functioning, emotional functioning, sensory functioning) and the self-reported well-being of children with ASD.
Results: A total of 24 studies with 717 participants (mean age range, 5.3 to 17.8 years; 141 [21.9%] female) were included. A meta-analysis from 13 studies indicated a significant negative moderate association between NBIs and social communication (standardized mean difference [SMD], -0.59; 95% CI, -0.85 to -0.34). For behavioral functioning outcomes, NBIs showed a significant moderate association with reduced hyperactivity (SMD, -0.56; 95% CI, -0.86 to -0.26) and a small to moderate association with reduced irritability (SMD, -0.49; 95% CI, -0.79 to -0.19). For sensory functioning, NBIs were significantly associated with improved inattention and distractibility (SMD, 1.13; 95% CI, 0.67 to 1.60). Significant moderate associations were observed in sensory seeking (SMD, 0.77; 95% CI, 0.33 to 1.22; P < .001; I2 = 0%) and sensory sensitivity (SMD, 0.56; 95% CI, 0.12 to 1.00; P = .01; I2 = 0%). Heterogeneity of the intervention effects was not high, and I2 ranged from 0% to 67%.
Conclusions and relevance: The findings of this systematic review and meta-analysis suggested an association of NBIs in group-based recreational therapy with experiential learning with positive short-term outcomes on sensory, social, and behavioral functioning for children with ASD. Future evidence using robust study design to aid the health and functional trajectories of children with ASD is recommended.