Assessing the transparency in reporting of clinical trials investigating manual therapy interventions for low back pain: A methodological review.

Rationale: Low back pain (LBP) is a common condition with a significant societal burden. Manual therapy is an effective treatment for LBP and recommended in clinical practice guidelines. While the quantity of literature supporting the use of manual therapy is large, the methodological quality and transparency of this collective work are unclear.

Aims and objectives: Explore the transparency in reporting of clinical trials assessing manual therapy interventions in patients with LBP by comparing planned components in the trial registration with what was reported in the published manuscript.

Methods: Three databases were searched to identify trials assessing the treatment effect of manual therapy for LBP from January 2005 to May 2023. Studies were included if the manual therapy consisted of thrust manipulations, mobilizations or muscle energy techniques.

Results: From 4462 studies initially identified, 167 studies remained in the final review after title, abstract and full-text review. Only 87 (52.1%) of the 167 studies were registered (n = 57 prospectively and n = 30 retrospectively). Primary outcomes in the publications were identical to the registration in 54 (62.1%) of the registered trials. Secondary outcomes in the publication were identical to the registration in 27 (31.0%) of the registered trials. The CONSORT reporting guideline was referenced in only 19 (21.8%) trials. Multiple discrepancies between registration and publication were noted for primary and secondary outcomes. All trials had eligibility criteria in the registration that matched their corresponding manuscript, while only four (4.6%) trial registrations addressed any type of statistical analysis plan.

Conclusion: Approximately half of the trials were not registered. Of those registered, only half were registered prospectively. Substantial discrepancies existed between registered and published outcomes that were never addressed by the authors, raising questions about potential bias. Transparency can be improved through more stringent requirements during manuscript submission to journals, and better reporting of the rationale for discrepancies between registration and publication.