Substantial discrepancies exist between registered protocol and published manuscript in trials on exercise for low back pain: a meta-research study

Oral
2024 Prague [Global Evidence Summit]
Bargeri S1, Basso G2, Castellini G1, Chiarotto A3, Geraci I2, Gianola S1, Innocenti T4, Ostelo R5, Testa M2
1Unit of Clinical Epidemiology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
2Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal Infantile Sciences (DINOGMI), University of Genova, Genova, Italy
3Department of Health Sciences, Faculty of Science, VU University Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands; Department of General Practice, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
4Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal Infantile Sciences (DINOGMI), University of Genova, Genova, Italy; Department of Health Sciences, Faculty of Science, VU University Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands; GIMBE Foundation, Bologna, Italy
5Department of Health Sciences, Faculty of Science, VU University Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands; Department of Epidemiology and Data Science, Amsterdam UMC location Vrije Universiteit & Amsterdam Movement Sciences, Musculoskeletal Health, The Netherlands

Background:

Reporting biases, prevalent in biomedical fields, can undermine evidence credibility.

Objectives:

We aim to evaluate the proportion of discrepancies related to reporting biases between registered protocols and published manuscripts in randomized controlled trials (RCTs) on exercise interventions for patients with chronic low back pain (cLBP).

Methods:

This is a meta-research study, prospectively registered. We started from the 2021 "Exercise therapy for chronic low back pain" Cochrane Review to select all RCTs reporting a protocol registration on a primary register of the World Health Organization International Clinical Trials Registry Platform or in ClinicalTrials.gov. Independent pairs of reviewers assessed discrepancies between registered protocol and published manuscript for the reporting of primary and secondary outcomes domains, measurement instruments, time-points, number of arms, and statistical analysis plans. Outcome discrepancies were characterized as addition, omission, upgrade, or downgrade.

Results:

We included 110 RCTs reporting an available protocol registration. Overall, 96 RCTs (87.3%) distinguished between primary and secondary outcomes. Of these, 37 RCTs (38.5%) reported 1 or more discrepancies in primary outcomes, and 76 RCTs (79.2%) reported 1 or more discrepancies in secondary outcomes. Focusing on discrepancies for the primary outcome, 60% of added, upgraded, or downgraded outcomes favored statistically significant effects. Few RCTs (n = 6) reported discrepancies in the number of arms. Statistical analysis plans were poorly reported in the registered protocols (n = 3) for being compared with the publications.

Conclusion:

We found substantial outcome discrepancies comparing registered protocols and published manuscripts in RCTs assessing exercise interventions for patients with cLBP, with some impacting the statistical significance of the effects. Readers are encouraged to approach RCT results in this field with caution.