2.4. Quality assessment

We considered the modified JADAD scale or the Oxford quality scoring system to assess the methodological quality of the publications. We chose this scoring system as it is the preferred quality assessment tool for randomized control trials (RCT) and that most of the included studies were RCTs.¹³

The JADAD scale mainly consists of six items which are described below in detail.

Item number 1: Was the study described as randomized? If yes, a score of 2 is given for acceptable randomization tools (e.g., computer-generated), and a score of 1 is given for inappropriate methods. If no, no score is given.

Item number 2: Was the trial stated as double-blind? If yes, a score of 2 is given for acceptable double-blinding methods (e.g., identical placebo), and a score of 1 is given for inappropriate methods. If no, no score is given.

Item number 3: Was there a description of dropouts and withdrawals? If yes, a score of 1, and if no, a score of 0 is given. Scores on the scale can range from 0 to 5, with higher numbers signifying higher quality. Studies with three or higher points are considered high quality, whereas those with less than three are considered low-quality trials.¹⁴

The other four additional questions were included from the modified version of the JADAD scale: Was there a clear description of the inclusion/exclusion criteria? Was the method used to assess adverse effects described? Was the method used to assess adverse effects described? Were the methods of statistical analysis described? Each positive response is worth one point, whereas a negative response earns no points—scores on the modified JADAD scale range from 0 to 8, with higher numbers indicating higher-quality trials. Scores of 1–3 denoted poor quality, while scores of 4–8 denoted excellent quality.¹⁵

Two authors (P.Sh. and Y.Kh.) independently assessed the quality of each eligible paper, which was subsequently double-checked by a third reviewer (K.M.).