The Cochrane Methodology Register (CMR) is a bibliography of publications that report on methods used in the conduct of controlled trials. It includes journal articles, books, and conference proceedings, and the content is sourced from MEDLINE and hand searches. CMR contains studies of methods used in reviews and more general methodological studies that could be relevant to anyone preparing systematic reviews. CMR records contain the title of the article, information on where it was published (bibliographic details), and, in some cases, a summary of the article. They do not contain the full text of the article.
The CMR was produced by the Cochrane UK, until 31st May 2012. There are currently no plans to reinstate the CMR and it is not receiving updates.* If you have any queries, please contact the Cochrane Community Service Team (support@cochrane.org).
The Publishers, John Wiley & Sons Ltd, thanks Update Software for the continued use of their data formats in the Cochrane Methodology Register (CMR).
*Last update in January 2019.
| Title | Assessing the quality of randomized trials: reliability of the Jadad scale. |
| Authors | Clark HD, Wells GA, Huet C, McAlister FA, Salmi LR, Fergusson D, Laupacis A |
| Source | Controlled Clinical Trials |
| Date of publication | 1999 |
| Volume | 20 |
| Issue | 5 |
| Pages | 448-452 |
| Abstract | An instrument was developed and validated by Jadad, et al. to assess the quality of clinical trials using studies from the pain literature. Our study determined the reliability of the Jadad scale and the effect of blinding on interrater agreement in another group of primary studies. Four raters independently assessed blinded and unblinded versions of 76 randomized trials. Interrater agreement was calculated among combinations of four raters for blinded and unblinded versions of the studies. A 4 x 2 x 2 repeated measures design was employed to evaluate the effect of blinding. The interrater agreement for the Jadad scale was poor (kappa 0.37 to 0.39), but agreement improved substantially (kappa 0.53 to 0.59) with removal of the third item (an explanation of withdrawals). Blinding did not significantly affect the Jadad scale scores. A more precise description of how to score the withdrawal item and careful conduct of a practice set of articles might improve interrater agreement. In contrast with the conclusions reached by Jadad, we were unable to demonstrate a significant effect of blinding on the quality scores. OTHER PUBLICATIONS OF THIS RESEARCH: Clark HD, Wells GA, Huet C, McAlister FA, Salmi LR, Fergusson D, Laupacis A. Assessing the quality of randomized trials: reliability of the Jadad scale [abstract] 14th Annual Meeting of the International Society of Technology Assessment in Health Care; 1998 Jun 7-10; Ottawa, Ontario, Canada:44. |
| CMR keywords | CMR: Review methodology - critical appraisal - scales and checklists - trials;CMR: Review methodology - data collection - blinding and reproducibility;CMRA2 |
| Reference type | Journal article |