Caution is necessary in interpreting musculoskeletal physiotherapy intervention outcomes: a methodological review of physiotherapy neuromusculoskeletal reviews.

Objectives: The physiotherapy literature lacks high-quality, registered systematic reviews (SRs) and 'trustworthy' randomized controlled trials (RCTs). It is unknown whether considering quality and 'trustworthiness' impact publication bias, heterogeneity, and the certainty of clinical recommendations observed in the literature.

Methods: We performed a methodological review of SRs investigating physiotherapy treatment of neuromusculoskeletal conditions indexed by MEDLINE, between 1 January 2018, and 25 October 2023. Blinded reviewers examined the prospective intent and quality of SRs and the 'trustworthiness' of RCTs included therein. Blinded reviewers extracted data for the variables of interest (Numeric Pain Rating Scale and Visual Analog Scale).

Results: Of the SRs identified (N = 677), 13 were included in the final review. These included a total of 109 RCTs, including duplicates. Only eight of these trials were deemed 'trustworthy.' Publication bias was identified, and heterogeneity across the trials (N = 55) included in the quantitative analysis was high (I² = 80.11%, 95% CI [75.88, 83.60]). Publication bias and heterogeneity were eliminated (I² = 0%, 95% CI [0.00, 37.44]) upon considering those prospectively registered (N = 14). Statistical significance, assessed via the p-value at baseline (<.001), was eliminated (p = .746) once prospective, external, and internal validity was considered. Statistical inference through estimation, evaluated via effect size, confidence intervals, and minimal detectable change, was not present at baseline and reduced throughout the screening process.

Discussion: Trials of musculoskeletal interventions to manage pain in patients with neuromusculoskeletal conditions lack certainty and confidence in their treatment effects and exhibit high heterogeneity. Statistically significant effects and heterogeneity are eliminated when considering 'trustworthy' quality evidence.

Conclusions: Consistent with previous findings, null effects, and low heterogeneity arise when considering the best available evidence. Meaningful effects are likely rare when assessed holistically using statistical inference through estimation and the confidence and certainty of the estimated effect.