Article type
Abstract
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.
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.