A Cochrane review [Abstract] 1 included 55 studies with a total of 163 471 subjects. The median duration of follow up was 12 months (with a range of six months to 12 years).Fourteen studies reported clinical event endpoints. The pooled ORs for total and coronary heart disease (CHD) mortality were 1.00 (95% CI 0.96 to 1.05; statistical heterogeneity I2 =62%; 14 studies, n=139 232) and 0.99 (95% CI 0.92 to 1.07; 11 studies, n= 132 564) respectively. Total mortality and combined fatal and non-fatal cardiovascular events showed benefits from intervention when confined to studies involving people with hypertension (16 studies) and diabetes (5 studies): OR 0.78 (95% CI 0.68 to 0.89; 6 studies, n= 17 852) and OR 0.71 (95% CI 0.61 to 0.83; 4 studies, n= 12 307), respectively. Net changes in systolic and diastolic blood pressure (53 studies), and blood cholesterol (50 studies) were (weighted mean differences) -2.71 mmHg (95% CI -3.49 to -1.93 mmHg), -2.13 mmHg (95% CI -2.67 to -1.58 mmHg) and -0.24 mmol/l (95% CI -0.32 to -0.16 mmol/l) respectively. The OR for reduction in smoking prevalence (20 studies) was 0.87 (95% CI 0.75 to 1.00). Marked heterogeneity (I2 > 85%) for all risk factor analyses was not explained by co-morbidities, allocation concealment, use of antihypertensive or cholesterol-lowering drugs, or by age of trial.
Comment: The quality of evidence is downgraded by study quality and by inconsistency (heterogeneity in interventions and outcomes).
Primary/Secondary Keywords