| 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 |
| Bazzano 2014 |
Some concerns |
"We used a computer‐generated, blocked randomization, stratified by sex, to allocate participants to 1 of the 2 diet groups." No information on allocation concealment. "Demographic characteristics and cardiovascular risk factors were similar between groups." No formal hypothesis tests were reported, but baseline values in Table 1 showed no apparent imbalance. |
Low risk of bias |
"...dietitians were not blinded to the study hypothesis" No information about participant blinding, however, blinding of participants for these dietary interventions is highly unlikely. No reasons or details about deviations from intended interventions reported. "All analyses were conducted using the intention‐to‐treat principle" n=148 randomised and n=148 analysed. |
Low risk of bias |
16/75 (21.3%) in the intervention and 13/73 (17.8%) in the control group did not have data. "...performed sensitivity analyses to assess the robustness of our conclusions and departures from the MAR assumption." "Results of sensitivity analyses using multiple imputation techniques to impute missing values were consistent with those presented in our primary analyses." |
Low risk of bias |
"Body weight ..... were measured to the nearest 0.1 kg and 0.1 cm, respectively, using a single calibrated scale" No evidence that a different method was used across intervention groups to measure the outcome. "....all outcome assessors were blinded to the diet group assignment." |
Some concerns |
"Study protocol and data set: Not available." No mention of pre‐specified data analysis plan. Trial registry outcomes amended after study publication; but trial registry entry at date prior to study publication mentions the outcome and timepoints. All time points mentioned in trial registry at date prior to study publication, were reported on in publication. Analysis intentions are not reported in sufficient detail to enable an assessment. |
Some concerns |
No specific information on allocation concealment. Lack of information in the pre‐registered methods. |
| 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". |
Low 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. Maximum likelihood mixed‐model analysis, including all participants who started in the study. |
Low risk of bias |
22/55 (40%) in the intervention and 16/52 (31%) in the control group did not have data available for this outcome. Results of the maximum likelihood mixed‐model analysis, including all participants who started the study, correspondend with that of the completers analysis (no statistically significant difference between groups). Independent t tests conducted on baseline characteristics of study dropouts and completers showed that data were missing at random. |
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 outcome. Analysis intentions are not reported in sufficient detail to enable an assessment. |
High risk of bias |
Allocation was not concealed. 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. |
Low risk of bias |
Open (masking not used). Deviations reported are expected to arise in usual care e.g. time, unable to commit to study protocol. Modified ITT conducted. |
Low risk of bias |
26/59 (44%) participants in the intervention group and 29/64 (45%) in the control group did not have data. "...intention to treat evaluation was conducted using maximal likelihood mixed model analysis with fixed and random effects to analyse expected mean changes over time. The secondary analysis was based on the 120 participants that had outcomes assessed at week 0 and commenced the dietary programme." "The secondary maximal likelihood mixed model analysis showed a similar pattern of results to the primary completer’s analysis". Results of a sensitivity analysis not reported, but MD reported at 52 weeks is the same with completers analysis (Table 3 in Wycherley et al 2012), as with ITT analysis (section 3.2 in Lutze et al 2013), but variances differ. |
Low risk of bias |
"…body weight was measured using calibrated electronic digital scales..." 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 judgement. |
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. Lack of information in the pre‐registered methods. |
