Rahnama 2012.
| Methods | RCT | |
| Participants | Included: 118 female students aged 18 and over, single, with a menstrual cycle that lasted from 21 to 35 days with 2 to 6 days of flow and average blood loss of 20 to 60 mL, with moderate to severe primary dysmenorrhoea (determined by a verbal multi‐dimensional scoring system) Excluded: women with diagnoses of a disease, a history of pregnancy or taking oral contraceptives, body mass index (BMI) < 19 kg/m2 or > 25 kg/m2, and mild dysmenorrhoea Age: the mean age of the intervention group = 21.4 years, control group = 21.3 years Source: students of the dormitories of Shahed University Location: Iran |
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| Interventions | Group 1: ginger powder (Zingiber officinale R. rhizomes) 500 mg per capsule (N = 59) Group 2: placebo (toast powder) 500 mg per capsule (N = 46) Both treatment groups took treatment 3 times a day in 2 different treatment protocols Protocol 1: ginger and placebo were given 2 days before the onset of the menstrual period and continued through the first 3 days of the menstrual period (1st cycle) Protocol 2: ginger and placebo were given only for the first 3 days of the menstrual period (2nd cycle) |
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| Outcomes |
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| Notes | Apparently this is not the same study as Rahnama 2010, as Rahnama 2012 references it as a separate study | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | High risk | “A random numbers table was used for assigning participants in a 1:1 ratio to receive placebo and ginger using a block of two. An odd number was assigned to one patient and an even number to the other patient in each block. For each individual student recruited in the trial, a coded package was used” Comment: using a block of 2 it is possible to predict future assignments (block size is fixed and small). |
| Allocation concealment (selection bias) | Low risk | “The randomization code was available only to the midwife who had not participated in the process of patient recruitment. The code was disclosed to the researchers when the statistical analysis had been completed by researchers.” |
| Blinding (performance bias and detection bias) All outcomes | Low risk | “The placebo capsules contained toast powder. The capsules were similar in shape, taste and colour but one set contained 500 mg ginger powder per capsule and the others were placebo capsules. The ginger capsules did not have distinguishable smell. The capsules were prepared in the Institute of Medicinal Plants and put into coded packages. Capsules and their packages were identical in appearance.” “This was a double‐ blind trial. Both the students and midwife providing care were blind to the treatment allocation. For this purpose, coded packages containing ginger and placebo capsules were used. The ginger and placebo capsules were identical in appearance, colour and taste.” “Students were asked to indicate a perception of pain intensity (most commonly) along a 10 cm horizontal line. Duration of pain was determined by asking each student to indicate the number of hours she had experienced pain during the first three days of the menstrual period.” |
| Incomplete outcome data (attrition bias) All outcomes | High risk | “Thirteen students who had received placebo discontinued the trial before completing the evaluation due to the fact that they indicated did not like to be involved in this research project any longer. More information on reasons for leaving was not captured. However, there were no significant differences between characteristics of 13 patients who left the placebo group and those who remained in the study (Table 1).” Comment: we found an imbalance regarding participants lost to follow‐up found; treatment (0%) versus placebo (13/46 = 28.3%). The overall dropout rate was 12.4% (13/105). |
| Selective reporting (reporting bias) | Unclear risk | Comment: the denominator for reporting of adverse events was unclear. |
| Other bias | Low risk | Comment: we did not identify any other potential sources of bias. |