A Cochrane review [Abstract]1 included 8 studies with a total of 2 100 subjects with high blood pressure and a mean age of 45 to 66 years. Mean treatment duration was 6 to 36 months. No study included mortality as a pre-defined outcome. One study evaluated the effects of dietary weight loss on a combined endpoint, consisting of the necessity of reinstating antihypertensive therapy and severe cardiovascular complications; weight reducing diet lowered the endpoint (HR 0.70, 95% CI 0.57 to 0.87) compared to no diet. Blood pressure was reduced in patients assigned to weight loss diets as compared to controls (WMD for systolic blood pressure -4.5 mm Hg, 95% CI -7.2 to -1.8 mm Hg, 3 studies; and WMD for diastolic blood pressure -3.2 mm Hg, 95% CI -4.8 to -1.5 mm Hg, 3 studies). Patients' body weight was also reduced in dietary weight loss groups as compared to controls (WMD -4.0 kg, 95% CI -4.8 to -3.2 kg; 5 studies). Two studies used withdrawal of antihypertensive medication as their primary outcome. Even though this was not considered a relevant outcome for this review, the results of these studies strengthen the finding of reduction of blood pressure by dietary weight loss interventions.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment and lack of blinding).
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