| Study |
Bias |
| Randomisation process |
Deviations from intended interventions |
Missing outcome data |
Measurement of the outcome |
Selection of the reported results |
Overall |
| Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
Authors' judgement |
Support for judgement |
| Tay 2008 |
High risk of bias |
From registry: "random allocation using computer software clinstat" "allocation is not concealed". "Baseline characteristics between diet groups were not different". |
High risk of bias |
From registry: "Open (masking not used)". Most deviations reported are expected to arise in usual care, e.g. work commitments, personal reasons. Per protocol completers analysis. 13/24 (54%) withdrawals in the intervention group and 16/25 (64%) in the control group were excluded from analysis due to unclear reasons; 2/24 (8%) withdrawals in the intervention and 2/25 (8%) in the control group were due to participants being 'unable to continue diet'. |
High risk of bias |
24/57 (42%) in the intervention and 25/61 (41%) in the control group did not have data available for this outcome. Completers analysis was conducted, including data only from participants who finished the study to week 52. Independent t tests conducted on baseline characteristics of study dropouts and completers showed that data were missing at random. Very high attrition in both groups, with limited reporting of reasons, but it is likely that with such high attrition missingness is possibly and likely dependent on the true value of the outcome. |
Low risk of bias |
Weight was measured using calibrated electronic digital scales (AMZ14; Mercury, Tokyo, Japan). No evidence that a different method was used across intervention groups to measure weight. From registry: "Open (masking not used)". Weight is not an observer‐reported outcome involving judgment. |
Some concerns |
No mention of pre‐specified analysis plan; trial registry at date prior to study publication mentions weight. Analysis intentions are not reported in sufficient detail to enable an assessment. |
High risk of bias |
Allocation was not concealed. A per protocol completers analysis was conducted, with some participants withdrawn due to an inability to continue with their assigned diet. Very high attrition in both groups, with limited reporting of reasons; therefore missingness could and is likely to depend on the true value of the outcome. Lack of information in the pre‐registered methods. |
| Wycherley 2012 |
High risk of bias |
"...participants were blocked, matched for age and body mass index, then randomised by the trial coordinators using computer‐generated random number allocation..." Allocation concealment: No (trial registry). From Table 3, only triglycerides were significantly different between groups at baseline (P < 0.05), of 17 characteristics measured. |
High risk of bias |
Open (masking not used). Deviations reported are expected to arise in usual care, e.g. relocated overseas, unable to commit to study protocol/time requirements. Per protocol analysis: 26/59 and 29/64 participants excluded due to being unable to commit to study protocol or did not receive intervention. Over 5% of total participants excluded with 9/26 in the intervention and 8/29 in the control group not analysed for reasons other than 'lost to contact'. |
High risk of bias |
26/59 (44%) participants in the intervention and 29/64 (45%) in the control group did not have data available. Modified ITT only done for change in weight at 52 weeks. Very high attrition in both groups, with limited reporting of reasons, but it is likely that with such high attrition missingness is possibly and likely dependent on the true value of the outcome. |
Low risk of bias |
"...body weight was measured using calibrated electronic digital scales (Mercury; AMZ 14, Tokyo, Japan)." No evidence that a different method was used across intervention groups to measure weight. Open (masking not used). Weight is not an observer‐reported outcome involving judgment. |
Some concerns |
No mention of pre‐specified analysis plan, but trial registry at date prior to study publication mentions the outcome and timepoint. The time point mentioned in trial registry at date prior to publication is reported on in publication. Analysis intentions are not reported in sufficient detail to enable an assessment. |
High risk of bias |
Allocation was not concealed. Some participants were excluded from the analysis due to an inability to commit to the study protocol. Very high attrition in both groups, with limited reporting of reasons; therefore missingness could and is likely to depend on the true value of the outcome. Lack of information in the pre‐registered methods. |
