In a cost-effectiveness assessment report, a detail descriptions were provided for the approaches in choosing the clinical trial data for meta analysis. After many clinical trials are selected, a 'Jadad Scale' was used to assess the quality of clinical trials.
Jadad Scale sometimes known as Jadad scoring or the Oxford quality scoring system, is a procedure to independently assess the methodological quality of a clincal trial. It is the most widely used such assessment in the world.
The Jadad score was used as the 'gold standard' to assess the methodological quality of studies. This validated score lies in the range 0-5. Studies are scored according to the presence of three key methodological features of randomization, blinding and accountability of all patients, including withdrawals.
According to NIH website Appendix E: The Jadad Score
A Method for assessing the quality of controlled clinical trials
Basic Jadad Score is assessed based on the answer to the following 5 questions.
The maximum score is 5.
Question Yes No
1. Was the study described as random? 1 0
2. Was the randomization scheme described and appropriate? 1 0
3. Was the study described as double-blind? 1 0
4. Was the method of double blinding appropriate? (Were both the patient and the assessor appropriately blinded?) 1 0
5. Was there a description of dropouts and withdrawals? 1 0
Quality Assessment Based on Jadad Score
Range of Score Quality
Wikipedia has a pretty good summary of the use of Jadad Scale.
Jadad Scale has been frequently used as a study selection criteria when the literature review or meta analysis are performed.
1. Jadad AR, Moore RA, Carroll D, et al. Assessing the quality of reports of randomized clinical trials: Is blinding necessary? Control Clin Trials 1996;17:1-12.