NDHS Open 2nd L&M 1968.
| Methods | RCT | |
| Participants | Free‐living men who had participated in NDHS 1st studies (USA)
CVD risk: low
Control: randomised 304, analysed 215
Intervention BC (this study had a range of interventions, we were interested in BC for the systematic review): randomised 194, analysed 179
Mean years in trial: control 0.6, intervention BC 0.6
% male: 100
Age: unclear (all 45 to 54) Baseline BMI: not reported |
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| Interventions | Reduced and modified fat vs usual diet Control aims: total fat 40%E, SFA 16%E to 18%E, dietary cholesterol 650 to 750 mg/d, P/S 0.4, X ‐ advice to continue usual diet Intervention aims: BC total fat 30%E to 40%E, SFA reduced, dietary cholesterol 350 to 450 mg/d, increased PUFA, P/S 1.5 to 2.0 Control methods: dietary advice to reduce saturated fat and cholesterol (plus 10 follow‐up visits with nutritionist), purchase of 'usual fat' items from a trial shop Intervention BC methods: dietary advice to reduce saturated fat and cholesterol (plus 10 follow‐up visits with nutritionist), plus purchase of appropriately reduced and modified fat items from a trial shop Weight goals: weight and calories not mentioned Total fat intake (through study): BC 32.5 (SD unclear) %E, control 35.5 (SD unclear) %E Saturated fat intake (through study): BC 7.4 (SD unclear) %E, control 12.0 (SD unclear) %E Style: food provided Setting: community |
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| Outcomes | Stated trial outcomes: lipid levels and dietary assessment Available outcomes: weight |
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| Notes | Weight data provided for the BC intervention group ‐1.8 kg (‐4 lb over 6 months), and ‐0.9 kg (‐2 lb) for modified fat diet G, ‐1.4 kg (‐3 lb) for modified fat diet F. No info provided for the control group (D) | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Stratified randomisation by the statistical centre |
| Allocation concealment (selection bias) | Low risk | Stratified randomisation by the statistical centre |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Some participants continued with advice to reduce saturated fat and purchased blinded foods from a trial shop, but half of the participants were instructed in their own purchase of appropriate foods from normal shops to compile their own dietary regimen |
| Incomplete outcome data (attrition bias) All outcomes | High risk | 104 of 498 (21%) lost over 0.6 years (> 5% per year) |
| Selective reporting (reporting bias) | Unclear risk | Protocol not seen |
| Other bias | Low risk | |
| Free of systematic difference in care? | Low risk | Trial shop used by both groups, plus dietary advice. See 'Control methods' and 'Intervention methods' in the 'Interventions' section above |
| Free of dietary differences other than fat? | Low risk | See 'Control aims' and 'Intervention aims' in the 'Interventions' section above |