Simon 1997.
| Methods | RCT, parallel, (low fat with low PUFA vs usual diet), 24 months Summary risk of bias: moderate or high |
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| Participants | Women with a high risk of breast cancer N: 98 intervention, 96 control (analysed 72 intervention: 75 control) Level of risk for CVD: low Male: 0% intervention, 0% control Mean age (SD): 46 (not reported) intervention, 46 (not reported) control Age range: not reported Smokers: not reported Hypertension: not reported Medications taken by ≥ 50% of those in the control group: not reported Medications taken by 20%‐49% of those in the control group: not reported Medications taken by some, but < 20% of the control group: not reported (those on statins excluded) Location: USA Ethenicity: white 89%, African American 9%, Hispanic 2% |
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| Interventions | Type: dietary advice Comparison: reduced fat including PUFA (intervention) vs usual diet Intervention: aims total fat 15% E; methods biweekly individual dietetic appointments over 3 months followed by monthly individual or group appointments, including education, goal setting, evaluation, feedback and self‐monitoring. Intervention delivered face to face by a dietitian Control: aim usual diet, no stated intervention(s) Dose aim: unclear PUFA Baseline 7.7% E PUFA Compliance by biomarkers: no fatty acid biomarkers reported, TC reported in a subgroup and fell by 0.34 mmol/L in intervention and fell by 0.08 mmol/L in control over 1 year Compliance by dietary intake: assessed using 3‐day 24‐h recalls every 3 months, 1 year data reported
Compliance, other methods: not reported Inclusion basis: no intention to increase total PUFA stated. Acheived total PUFA reduction of 6.7% E in intervention compared to control at 1 year, > 10% higher than baseline 7.7% E from total PUFA PUFA dose: ‐6.7% E PUFA Compliance: dietary assessment Duration of intervention: 24 months (mean years in trial: control 1.8, intervention 1.7) |
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| Outcomes | Main trial outcome: intervention feasibility Dropouts: unclear intervention, unclear control Available outcomes: TC, TG, LDL and HDL (2 deaths, but unclear in which arms, 8 cancer diagnosis but not clear in which arms), (weight, BMI, % body fat and waist‐hip ratio reported but all too unbalanced at baseline to use) Trial author contact: Dr Simon confirmed that some deaths occurred (but not in which arms) and sent a further reference. |
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| Notes | Trial funding: Marilyn J Smith Fund, Harper‐Grace Hospitals, the Wesley Foundation, National Cancer Institute, Karmanos Cancer Institute Core Grant, the United Foundation of Detroit Trialaim was to reduce total fat to 15% E (SFA not mentioned), but PUFA fat intake in the intervention group was significantly lower than in the control group. Note: PUFA lower in intervention arm, so higher PUFA arm is the control |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Stratified by age and randomised (block size 2) |
| Allocation concealment (selection bias) | Unclear risk | Allocation method not clearly enough described |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | Participants not blinded (as given dietary advice or not), personnel unclear |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Not reported |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | Unclear, deaths, cancer and CV events are dropouts ‐ unclear if any data missing |
| Selective reporting (reporting bias) | Unclear risk | No protocol or trials registry entry found |
| Attention bias | High risk | Time and attention in the intervention group not mirrored in control |
| Compliance | High risk | No fatty acid biomarkers reported, TC reported in a subgroup and fell by 0.34 mmol/L in intervention and fell by 0.08 mmol/L in control over 1 year (but control group should have been higher in PUFA in this trial) |
| Other bias | Low risk | None noted |