Supplementary Material for: Effect of abdominal massage on constipation: A systematic review and meta-analysis of randomized controlled studies

Abstract Background: Constipation is a common gastrointestinal disease that seriously affects the quality of life. Although abdominal massage (AM) has shown some therapeutic effects in some clinical practices, high-quality evidence on AM treating constipation is still scarce. Objective: This systematic review and meta-analysis aims to thoroughly investigate the efficacy and safety of AM treatment for constipation. Methods: According to the PRISMA guidelines, we searched the Pubmed, Web of Science, Cochrane Library, Embase, and Scopus databases. English studies published up to July 2025 were searched. We searched for studies of randomized controlled trials (RCTs) of AM for constipation and screened them by inclusion and exclusion criteria. The risk of bias was assessed using the Cochrane Collaboration Network tool (Revman5.30). The I2 statistic measured the heterogeneity of trials. Effect sizes were expressed by standardized mean difference (SMD) and 95% confidence intervals (CI) for outcomes. Additionally, sensitivity analysis, subgroup analysis, and meta-regression analysis were conducted to further explore the sources of heterogeneity. Results: A total of 25 RCTs published from 2009-2024 involving 1508 subjects were included after screening, of which 19 were included in the Meta-analysis. In the quality assessment of the included studies, the overall study quality was moderately high and the overall risk of bias was low. Our findings demonstrated that AM significantly improved constipation severity in patients with constipation (SMD = -1.64, 95% CI = [-2.26, -1.01], P < 0.00001); quality of life (SMD = - 1.71, 95% CI = [-2.31, -1.11], P < 0.00001); number of bowel movements per week (SMD = 1.17, 95% CI = [0.70, 1.65], P < 0.00001); stool consistency (SMD = 1.2, 95% CI = [0.05, 2.36], P = 0.04) and pain intensity associated with constipation (SMD = -1.26, 95% CI = [-1.74, -0.77], P < 0.00001). Subgroup analyses further indicated that even short-term AM interventions may have a positive impact on patients with constipation. Additionally, regarding safety, most of the included trials did not report adverse events. Conclusion: AM is safe and effective in the treatment of constipation. Although the results of sensitivity analysis and subgroup analysis provide important guidance for clinical selection of AM treatment options, these results need to be interpreted with caution given the diversity of constipation etiologies.