Does manual therapy meaningfully change quantitative sensory testing and patient reported outcome measures in patients with musculoskeletal impairments related to the spine?: A 'trustworthy' systematic review and meta-analysis.

OBJECTIVES:To perform a 'trustworthy' systematic review (SR) with meta-analysis on the potential mechanisms of manual therapy used to treat spinal impairments. DESIGN:SR with meta-analysis. LITERATURE SEARCH:Articles published between January 2010 and October 2022 from CENTRAL, CINAHL, MEDLINE, PubMed, ProQuest, and PEDro. METHODS:This SR included English-language randomized clinical trials (RCTs) involving manual therapy to treat spinal impairments in adults. The primary outcome was pressure pain thresholds (PPTs). To synthesize RCTs with high confidence in estimated effects using the GRADE, RCTs with questionable prospective, external, and internal validity, and high risk of bias (RoB) were excluded. RESULTS:Following title and abstract screening, 89 full-text RCTs were reviewed. Twenty-two studies included the criteria of interest. Sixteen were not prospectively registered, two contained discussion/conclusions judged to be inconsistent with the registry, and one was rated as having a high RoB. Three studies met the inclusion criteria; heterogeneous interventions and locations for PPT testing prevented synthesis into practice recommendations. The two studies with high confidence in estimated effects had small effect sizes, and one study had confidence intervals that crossed zero for the outcome measures of interest. DISCUSSION:Standardized PPT testing, as a potential measure of centrally mediated pain, could provide clues regarding the mechanisms of manual therapy or help identify/refine research questions. CONCLUSION:High-quality RCTs could not be synthesized into strong conclusions secondary to the dissimilarity in research designs. Future research regarding quantitative sensory testing should develop RCTs with high confidence in estimated effects that can be translated into strong recommendations.