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Parma Yamato T.1, Maher C.1, Koes B.2, Moseley A.1
1The George Institute for Global Health, The University of Sydney, Musculoskeletal Division, Sydney, Australia, 2Erasmus MC, Department of Genreal Practice, Rotterdam, Netherlands
Background: The PEDro scale has been widely used to investigate methodological quality in physical therapy randomised controlled trials; however its validity has not been tested for pharmaceutical trials.
Purpose: The aim of this study was to investigate the validity and inter-rater reliability of the PEDro scale for pharmaceutical trials. The reliability was also examined for the Cochrane Back and Neck (CBN) Group risk of bias tool.
Methods: This is a secondary analysis of data from a previous study. We considered randomised placebo controlled trials evaluating any pain medication for chronic spinal pain or osteoarthritis. Convergent validity was evaluated by correlating the PEDro score with the summary score of the CBN risk of bias tool. The construct validity was tested using a linear regression analysis to determine the degree to which the total PEDro score is associated with treatment effect sizes, journal impact factor and the summary score for the CBN risk of bias tool. The inter-rater reliability was estimated using the Kappa coefficient and 95%CI for the PEDro scale and CBN risk of bias tool.
Results: Fifty-three trials were included, comprising 91 comparisons included in the analyses. The correlation between the two instruments was 0.83 (95% CI 0.76 to 0.88) after adjusting for reliability, indicating strong convergence. The PEDro score was inversely associated with effect sizes, significantly associated with the summary score for the CBN risk of bias tool, and not associated with the journal impact. The inter-rater reliability for each item of the PEDro scale and CBN risk of bias tool was at least substantial for most items (>0.60). The ICC for the PEDro score was 0.80 (95% CI 0.68 to 0.88), and for the CBN risk of bias tool was 0.81 (95% CI 0.69 to 0.88).
Conclusion(s): There was evidence for the convergent and construct validity for the PEDro scale to evaluate methodological quality in pharmaceutical trials. The inter-rater reliability was considered as substantial to perfect for most items.
Implications: The PEDro scale has acceptable measurement properties to evaluate methodological quality of pharmaceutical trials.
Funding acknowledgements: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Topic: Research methodology & knowledge translation
Ethics approval: Ethics approval was not required in this study.
All authors, affiliations and abstracts have been published as submitted.
