Meta-epidemiologic review: Blinding and sham treatment in clinical trial design for osteopathic manipulative treatment research

To analyze the consistency of study designs in osteopathic manipulative treatment (OMT) research, focusing on blinding protocols and the use of sham treatments. PubMed and CINAHL were searched in January 2022. A total of 83 research studies between 2009 and 2021 were selected based on the presence of a double- or single-blind study design and/or sham treatment. Data regarding the primary outcome measures, blinding design, measures used to determine success of blinding, osteopathic technique used, and sham technique used for each eligible study were extracted and compared among different study designs. A total of 5968 subjects participated in the 83 trials. The study population mainly consisted of asymptomatic individuals (25 %) and chronic back pain patients (19 %). Light touch was employed most commonly (49 %) as the sham treatment, followed by unrelated sham (20 %) and incomplete maneuvers (20 %). Most studies blinded the subjects (80 %) or the outcome evaluator/data analyzer (71 %), while only 20 % studies blinded the osteopathic physicians. Strict double-blinding is achievable for OMT clinical research by blinding the subjects and data collectors/analyzers rather than the osteopaths providing the actual treatment. The use of questionnaires to determine the success of blinding should be considered. Additionally, including OMT-naïve subjects is preferred to enhance blinding success. When designing a sham treatment, careful consideration should be given to blinding the data collector, accounting for the placebo effect, and incorporating an additional no-treatment control group to improve the rigor of the study design. •There is a general paucity of osteopathic manipulative treatment (OMT) clinical trials. The design of OMT clinical studies has room to improve.•Double-blind can be achieved by blinding the subjects and evaluators and data collectors/analyzers, which is much more practical than blinding the osteopaths who provide the active treatments.•Various methods have been utilized as sham control for OMT, including light touch, unrelated sham, incomplete maneuver, no-treatment control, purposefully incorrect positioning, and combination of several techniques. Among them, light touch is most frequently adopted (49 % of studies).