Sydney Diet‐Heart 1978.

Study characteristics
Methods	RCT Sydney Diet‐Heart Trial Summary risk of bias: moderate to high
Participants	Men with previous MI (Australia) CVD risk: high Control: randomised 237, analysed 221 at 2 years Intervention: randomised 221, analysed 205 at 2 years Mean years in trial: control 4.3, intervention 4.3 % male: 100 Age: mean control 49.1 (SD 6.5), intervention 48.7 (SD 6.8) Ethnicity: not stated Statins use allowed? Unclear (use of medication did not appear to be an exclusion criteria) % taking statins: Not reported (probably none as too early, pre‐1980)
Interventions	Modified fat diet vs usual diet Control aims: reduction in energy if overweight, no other specific dietary advice, allowed to use PUFA margarine instead of butter Intervention aims: SFA 10%E, PUFA 15%E, reduction in energy if overweight, dietary chol < 300 mg/day Control methods: no specific dietary instruction (except re weight) Intervention methods: advised and tutored individually, diet assessed 3 times in 1st year and twice annually thereafter Intervention was delivered face‐to‐face individually but unclear by whom Total fat intake, %E ("during follow‐up"): int 38.3 (SD 5.9), cont 38.1 (SD 5.4) (mean difference 0.20, 95% CI ‐0.88 to 1.28) no significant difference Saturated fat intake, %E ("during follow‐up"): int 9.8 (SD 2.6), cont 13.5 (SD 3.2) (mean difference ‐3.70, 95% CI ‐4.25 to ‐3.15) significant reduction PUFA intake, %E ("during follow‐up"): int 15.1 (SD 4.3), cont 8.9 (SD 3.5) (mean difference 6.20, 95% CI 5.45 to 6.95) significant increase PUFA n‐3 intake: not reported PUFA n‐6 intake: not reported MUFA intake, %E ("during follow‐up"): int 11.5 (SD 2.1), cont 13.8 (SD 2.5) (mean difference ‐2.30, 95% CI ‐2.74 to ‐1.86) significant reduction CHO intake, %E ("during follow‐up"): int 40.9 (SD 7.3), cont 40.3 (SD 7.3) (mean difference 0.60, 95% CI ‐0.79 to 1.99) no significant difference Protein intake, %E ("during follow‐up"): int 15.2 (SD 2.8), cont 15.7 (SD 3.4) (mean difference ‐0.50, 95% CI ‐1.09 to 0.09) no significant difference Trans fat intake: not reported Primary replacement for saturated fat: mainly PUFA (based on dietary aims and achievements) Style: diet advice Setting: community
Outcomes	Stated trial outcomes: cardiovascular mortality and morbidity Data available on total mortality? yes Cardiovascular mortality? yes (exact events included not stated) Events available for combined cardiovascular events: none Secondary outcomes: CHD deaths (exact events included not stated) Tertiary outcomes: total cholesterol, TG, BMI, sBP, dBP
Notes	Study duration 7 years Study aim was saturated fat 10%E, and saturated fat intake in the intervention group was less than 80% of that in the control (73%) SFA reduction aimed and achieved Total serum cholesterol, difference between intervention and control, mmol/L: ‐0.30 (95% CI ‐0.51 to ‐0.09), statistically significant reduction Trial dates: Recruitment 1966 to [unclear] and followed for 2 to 7 years Funding: Life Insurance Medical Research Fund of Australia and New Zealand Declarations of Interest of primary researchers: none stated, all authors worked for academic or health institutions.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "table of random numbers ... generated by a research assistant and was concealed until after medical evaluations and testing at baseline were completed".
Allocation concealment (selection bias)	Low risk	As above
Blinding of participants and personnel (performance bias) All outcomes	High risk	Very difficult to blind trials where participants need to make their own dietary changes
Blinding of outcome assessment (detection bias) CVD outcomes	Low risk	Initially masked to group assignment (though success of blinding not checked)
Blinding of outcome assessment (detection bias) All‐cause mortality	Low risk	Blinding is not relevant in assessment of mortality.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Survival analysis used
Selective reporting (reporting bias)	Low risk	Not relevant for primary and secondary outcomes as all trialists were asked for data
Free of systematic difference in care?	High risk	Advice and follow‐up in intervention group, not in control. See control and intervention methods in the Interventions section of the table of Characteristics of included studies
Stated aim to reduce SFA	Low risk	Aim to reduce SFA stated
Achieved SFA reduction	Low risk	SFA reduction achieved
Achieved TC reduction	Low risk	Statistically significant TC fall
Other bias	Low risk	None noted