The Jadad scale assesses the quality of published clinical trials based methods relevant to random assignment, double blinding, and the flow of patients. There are 7 items. The last 2 attract a negative score, which means that the range of possible scores is 0 (bad) to 5 (good):
1. Was the study described as randomized (this includes words such as randomly, random, and randomisation)? (+1 Point)
2. Was the method used to generate the sequence of randomisation described and appropriate (table of random numbers, computer-generated, etc)? (+1 Point)
3. Was the study described as double blind? (+1 Point)
4. Was the method of double blinding described and appropriate (identical placebo, active placebo, dummy, etc)? (+1 Point)
5. Was there a description of withdrawals and dropouts? (+1 Point)
6. Deduct one point if the method used to generate the sequence of randomisation was described and it was inappropriate (patients were allocated alternately, or according to date of birth, hospital number, etc)
7. Deduct one point if the study was described as double blind but the method of blinding was inappropriate (e.g., comparison of tablet vs. injection with no double dummy).
Jadad AR, Moore RA, Carroll D, et al. Assessing the quality of reports of randomized clinical trials: is blinding necessary? Controlled Clin. Trials 1996; 17: 1-12.
Jüni P, Witschi A, Bloch R, Egger M. The hazards of scoring the quality of clinical trials for meta-analysis. J.A.M.A. 1999; 282: 1054-60.