Table 3 Risk bias included studies
Study, year | Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessors | Incomplete outcome data | Selective reporting | Other sources of bias |
|---|---|---|---|---|---|---|---|
Gaede et al. (2001) [95] | Unclear (not stated) | Unclear (not stated) | Low risk (double blind) | Unclear (not stated) | Low risk (no drop-out) | Unclear (not stated) | Unclear (not stated) |
Farvid et al. (2005) [96] | Low risk (block randomization procedure) | Low risk (the supplement and placebo capsules looked identical) | Low risk (double blind) | Unclear (not stated) | Low risk (two drop-out) | Unclear (not stated) | Unclear (not stated) |
Giannini et al. (2007) [89] | Unclear (not stated) | Low risk (Vitamin E and placebo were capsules of the same size, shape, and color) | Low risk (double blind) | Unclear (not stated) | Low risk (no drop-out) | Unclear (not stated) | Unclear (not stated) |
Parham et al. (2008) [92] | Low risk (card-shufflfling randomization) | Low risk (the same as the zinc capsules, in size, shape and color.) | Low risk (double blind) | Unclear (not stated) | Low risk (eight drop-out: four in the control group; four in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Khajehdehi et al. (2011) [97] | Unclear (not stated) | Low Risk (three capsules identical in colour and size, containing starch) | Low risk (double blind) | Unclear (not stated) | Low risk (no drop-out) | Unclear (not stated) | Unclear (not stated) |
Fallahzadeh et al. (2012) [98] | Low risk (sequence generated by Random Allocation Software) | Low Risk (similar in size, shape, weight, color, and taste.) | Low risk (double blind) | Unclear (not stated) | Low risk (four drop-out: two in the control group; two in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Noori et al. (2013) [99] | Unclear (not stated) | Unclear (not stated) | Low risk (double blind) | Unclear (not stated) | Low risk (no drop-out) | Unclear (not stated) | Unclear (not stated) |
Haghighat et al. (2014) [90] | Low risk (participants were assigned into two groups randomly by using a random number table) | Unclear (not stated) | Low risk (double blind) | Unclear (not stated) | Low risk (five drop-out: three in the control group; two in the intervention group) | Low risk (all the specifified outcomes have been reported) | Unclear (not stated) |
Zhu et al. (2016) [93] | Low risk (randomization sequence was created using SAS version 9.2 | Unclear (not stated) | Low risk (double blind) | Unclear (not stated) | Low risk (20 drop-out: 13 in the control group; 7 in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Bahmani et al. (2016) [100] | Low risk (computer- generated random Numbers) | Low Risk (placebo capsules (starch), including colour, shape, size and packaging, was identical to Se capsules) | Low risk (double blind) | Low risk (concealed from the researchers and participants until the fifinal analyses were completed.) | Low risk (eight drop-out: four in the control group;four in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Borges et al. (2016) [101] | Low risk (website Randomization.com was used to Generate) | Low Risk (All drugs and placebo tablets were similar in size, shape, weight, and color.) | Low risk (double blind) | Unclear (not stated) | Low risk (five drop-out: three in the control group; two in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Elbarbary et al. (2018) [102] | Low risk (computer-generated randomization sequence) | Low risk (drug pharmacy with allocation concealment by opaque sequentially numbered sealed envelope) | Low risk (double blind) | Unclear (not stated) | Low risk (five drop-out: three in the control group;two in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Aghadavod et al. (2018) [103] | Low risk ( using a random number table) | Low Risk (similar in shape and size to vitamin E capsule) | Low risk (double blind) | Unclear (not stated) | Low risk (six drop-out: three in the control group; three in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Gholnari et al. (2018) [104] | Low risk (computer-generated random numbers) | Unclear (placebo (cellulose)) | Low risk (double blind) | Unclear (not stated) | Low risk (three drop-out in intervention group) | Unclear (not stated) | Unclear (not stated) |
Tan et al. (2019) [105] | Low risk (computer-generated random sequence) | Low Risk (investigational products was kept Confidential) | Low risk (double blind) | Unclear (not stated) | Low risk (no drop-out) | Unclear (not stated) | High Risk (tocotrienol measurements were not accurate.) |
Sattarinezhad et al. (2019) [106] | Low risk (randomized list generated by Microsoft Excel software) | Low Risk (identical shapes, sizes and colours of the resveratrol and placebo containers) | Low risk (double blind) | Unclear (not stated) | Low risk (four drop-out: two in the control group; two in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Satari et al. (2021) [107] | Unclear (not stated) | Low Risk (Melatonin and placebo capsules were produced in the same shape and Package) | Low risk (double blind) | Unclear (not stated) | Low risk (eight drop-out: four in the control group; four in the intervention group) | Unclear (not stated) | Unclear (not stated) |
Koay et al. (2021) [94] | Low risk (computer-generated random sequence) | Low risk (identical looking capsules (tocotrienol-free palm oil capsules) | Low risk (double blind) | Unclear (not stated) | Low risk (two drop-out) | Unclear (not stated) | Unclear (not stated) |
Jaafarinia et al. (2022) [108] | Low risk (Microsoft Excel software with a block randomization method) | Low risk (Both intevention and placebo tablets were similar in size, shape, weight, and color) | Low risk (triple-blind) | Low risk (triple-blind) | Low risk (four drop-out: three in the control group; one in the intervention group) | Unclear (not stated) | Unclear (not stated) |