Construct validity of the Physiotherapy Evidence Database (PEDRo) quality scale for randomized trials: Item Response Theory analyses.
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BORIS DOI
Date of Publication
March 2020
Publication Type
Article
Division/Institute
Contributor
Albanese, Emiliano | |
Armijo-Olivo, Susan | |
Ha, Christine |
Series
Research Synthesis Methods
ISSN or ISBN (if monograph)
1759-2879
Publisher
Wiley
Language
English
Publisher DOI
PubMed ID
31733091
Uncontrolled Keywords
Description
BACKGROUND
There is agreement that the methodological quality of randomized trials should be assessed in systematic reviews, but debate on how this should be done. We conducted a construct validation study of the Physiotherapy Evidence Database (PEDro) scale, which is widely used to assess the quality of trials in physical therapy and rehabilitation.
METHODS
We analyzed 345 trials that were included in Cochrane reviews, and for which a PEDro summary score was available. We used one- and two-parameter logistic item response theory (IRT) models to study the psychometric properties of the PEDro scale, and assessed the items' difficulty and discrimination parameters. We ran goodness of fit post-estimations and examined the IRT unidimensionality assumption with a multidimensional IRT model (MIRT).
RESULTS
Out of a maximum of 10, the mean PEDro summary score was 5.46 (SD=1.51). The allocation concealment and intention-to-treat scale items contributed most of the information on the underlying construct (with discriminations of 1.79 and 2.05, respectively) at similar difficulties (0.63 and 0.65, respectively). The other items provided little additional information, and did not distinguish trials of different quality. There was substantial evidence of departure from the unidimensionality assumption, suggesting that the PEDro items relate to more than one latent trait.
CONCLUSIONS
Our findings question the construct validity of the PEDro scale to assess the methodological quality of clinical trials. PEDro summary scores should not be used; rather the physiotherapy community should consider working with the individual items of the scale.
There is agreement that the methodological quality of randomized trials should be assessed in systematic reviews, but debate on how this should be done. We conducted a construct validation study of the Physiotherapy Evidence Database (PEDro) scale, which is widely used to assess the quality of trials in physical therapy and rehabilitation.
METHODS
We analyzed 345 trials that were included in Cochrane reviews, and for which a PEDro summary score was available. We used one- and two-parameter logistic item response theory (IRT) models to study the psychometric properties of the PEDro scale, and assessed the items' difficulty and discrimination parameters. We ran goodness of fit post-estimations and examined the IRT unidimensionality assumption with a multidimensional IRT model (MIRT).
RESULTS
Out of a maximum of 10, the mean PEDro summary score was 5.46 (SD=1.51). The allocation concealment and intention-to-treat scale items contributed most of the information on the underlying construct (with discriminations of 1.79 and 2.05, respectively) at similar difficulties (0.63 and 0.65, respectively). The other items provided little additional information, and did not distinguish trials of different quality. There was substantial evidence of departure from the unidimensionality assumption, suggesting that the PEDro items relate to more than one latent trait.
CONCLUSIONS
Our findings question the construct validity of the PEDro scale to assess the methodological quality of clinical trials. PEDro summary scores should not be used; rather the physiotherapy community should consider working with the individual items of the scale.
File(s)
| File | File Type | Format | Size | License | Publisher/Copright statement | Content | |
|---|---|---|---|---|---|---|---|
| Albanese ResSynthMethods 2020.pdf | text | Adobe PDF | 640.3 KB | Attribution (CC BY 4.0) | published |