Summary of findings 3. Mediterranean dietary intervention compared to usual care for secondary prevention of cardiovascular disease.
| Mediterranean dietary intervention compared to usual care for secondary prevention of cardiovascular disease | ||||||
| Patient or population: adults with established cardiovascular disease Setting: community Intervention: Mediterranean dietary intervention Comparison: usual care | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with usual care | Risk with Mediterranean dietary intervention | |||||
| CVD mortality Follow‐up: mean 46 months | Study population | RR 0.35 (0.15 to 0.82) | 605 (1 RCT) | ⊕⊕⊝⊝ LOW 1 | — | |
| 63 per 1000 | 22 per 1000 (9 to 51) | |||||
| Total mortality Follow‐up: mean 4 years | Study population | RR 0.44 (0.21 to 0.92) | 605 (1 RCT) | ⊕⊕⊝⊝ LOW 1 | — | |
| 79 per 1000 | 35 per 1000 (17 to 73) | |||||
| Total cholesterol (mmol/L), change from baseline Follow‐up: range 1 year to 4 years | The mean total cholesterol change from baseline ranged from ‐0.22 to ‐0.31 mmol/L | MD 0.07 mmol/L higher (0.19 lower to 0.33 higher) | — | 441 (2 RCTs) | ⊕⊕⊝⊝ LOW 2 | — |
| LDL cholesterol (mmol/L), change from baseline Follow‐up: range 1 year to 4 years | The mean LDL cholesterol change from baseline ranged from ‐0.26 to ‐0.41 | MD 0.11 higher (0.09 lower to 0.31 higher) | — | 441 (2 RCTs) | ⊕⊕⊝⊝ LOW 2 | — |
| HDL cholesterol (mmol/L), change from baseline Follow‐up: range 1 year to 4 years | The mean HDL cholesterol change from baseline ranged from 0 to 0.15 mmol/L | MD 0.01 mmol/L lower (0.08 lower to 0.07 higher) | — | 441 (2 RCTs) | ⊕⊕⊝⊝ LOW 2 | — |
| Triglycerides (mmol/L), change from baseline Follow‐up: range 1 year to 4 years | The mean triglycerides change from baseline ranged from ‐0.02 to ‐0.08 mmol/L | MD 0.14 mmol/L lower (0.38 lower to 0.1 higher) | — | 441 (2 RCTs) | ⊕⊕⊝⊝ LOW 2 | — |
| Systolic blood pressure (mmHg), change from baseline Follow‐up: 4 years | The mean systolic blood pressure change from baseline was 9 mmHg | MD 2 mmHg lower (5.29 lower to 1.29 higher) | — | 339 (1 RCT) | ⊕⊝⊝⊝ VERY LOW 1 3 | — |
| Diastolic blood pressure (mmHg), change from baseline Follow‐up: 4 years | The mean diastolic blood pressure change from baseline was 5 mmHg | MD 1 mmHg lower (4.29 lower to 2.29 higher) | — | 339 (1 RCT) | ⊕⊝⊝⊝ VERY LOW 1 4 | — |
| Adverse events | Adverse effects were reported in only one RCT. Two of 302 CHD patients noted margarine‐related side effects of colitis and diarrhoea in The Lyon Diet Heart Study. | — | 605 (1 RCT) | ⊕⊕⊝⊝ LOW 1 | — | |
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; CVD: cardiovascular disease; HDL: high‐density lipoprotein;LDL: low‐density lipoprotein; MD: mean difference; RCT: randomised controlled trial; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence High certainty: We are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
1Downgraded by two levels for risk of bias. The only included study had an unclear randomisation method and the modified Zelen design may have introduced other biases, although the study was at low risk of bias for allocation concealment and attrition.
2Downgraded by two levels for risk of bias as both included studies were at unclear risk of selection bias or attrition bias, or both, and the majority weight in the meta‐analysis was for the study with a modified Zelen design.
3Downgraded by one level for imprecision due to small number of participants (N < 400).
4Downgraded by two levels for imprecision due to small number of participants and wide CI that includes both important increases and decreases in the outcome.