WHT Feasibility 1990.

Methods	RCT
Participants	Women at increased risk of breast cancer (USA) CVD risk: low Control: randomised 184, analysed 159 Intervention: randomised 119, analysed 102 Mean years in trial: control 1.9, randomised 1.9 % male: 0% Age: mean control 55.6 (SD 6.3), intervention 55.6 (SD 6.2) Baseline BMI: mean intervention 26 (SD 4), control 25 (SD 4)
Interventions	Reduced fat vs usual diet Control aims: maintain usual diet Intervention aims: 20%E from fat Control methods: no advice provided, only seen at baseline, then 6, 12 and 24 months for assessment Intervention methods: women were given flexible diet plans and responsible for their own monitoring, they had individual appointments with a nutritionist at 2 and 12 weeks, plus small group meetings (weekly for 8 weeks, then biweekly for 8 weeks, then monthly to 2 years) Weight goals: weight and calories not mentioned Total fat intake (at 2 years): intervention 22.6 (SD 7.1), control 36.8 (SD 8.0) %E Saturated fat intake (at 2 years): intervention 7.2 (SD 2.7), control 12.3 (SD 3.6) %E Style: diet advice Setting: community
Outcomes	Stated trial outcomes: dietary intake/feasibility Available outcomes: weight, total cholesterol
Notes	Weight data provided at 6, 12 and 24 months. 2‐year data used in main analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"randomised"
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	High risk	Participants were not blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	42 of 303 (14%) lost over 2 years (> 5% per year)
Selective reporting (reporting bias)	Low risk	Design paper published, weight and serum total cholesterol reported
Other bias	Low risk
Free of systematic difference in care?	High risk	Different levels of attention and time
Free of dietary differences other than fat?	Low risk	Focus on fat only