ContextReviews exploring harm outcomes such as adverse effects (AE), all cause dropouts (ACD), dropouts due to inefficacy, and dropouts due to AE associated with osteopathic manipulative treatment (OMT) or osteopathic manual therapy (OMTh) are scant.ObjectivesTo explore the overall AE, ACD, dropouts due to inefficacy, and AE in chronic noncancerous pain (CNCP) patients receiving OMTh through a systematic review of previous literature.MethodsFor this systematic review and meta-analysis, the authors searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Physiotherapy Evidence Database (PEDro), EMCare, and Allied and Complementary Medicine Database (AMED), and Ostmed.Dr, as well as the bibliographical references of previous systematic reviews evaluating OMTh for pain severity, disability, quality of life, and return to work outcomes. Randomized controlled trials with CNCP patients 18 years or older with OMTh as an active or combination intervention and the presence of a control or combination group were eligible for inclusion. In this sub-study of a previous, larger systematic review, 11 studies (n=1,015) reported data that allowed the authors to perform meta-analyses on ACD and dropouts due to AE. The risk of bias (ROB) was assessed with the Cochrane ROB tool and the quality of evidence was determined with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.ResultsThe pooled analysis showed that ACD was not significantly different for visceral OMTh (vOMTh) vs. OMTh control (odds ratio [OR]=2.66 [95% confidence interval [[CI]], 0.28, 24.93]) or for OMTh vs. standard care (OR=1.26 [95% CI, 0.84, 1.89]; I2=0%). Single study analysis showed that OMTh results were nonsignificant in comparison with chemonucleolysis, gabapentin, and exercise. OMTh in combination with gabapentin (vs. gabapentin alone) and OMTh in combination with exercise (vs. exercise alone) showed nonsignificant ACD. Dropouts due to AE were not significantly different, but the results could not be pooled due to an insufficient number of studies.ConclusionsMost articles did not explicitly report AEs, ACD rates, or dropouts due to AEs and inefficacy. The limited data available on dropouts showed that OMTh was well tolerated compared with control interventions, and that the ACD and dropouts due to AEs were not significantly different than comparators. Future trials should focus on explicit reporting of dropouts along with beneficial outcomes to provide a better understanding of OMTh efficacy.