Intervention Review

Long-term effects of weight-reducing diets in hypertensive patients

  1. Andrea Siebenhofer1,*,
  2. Klaus Jeitler2,
  3. Andrea Berghold3,
  4. Andreas Waltering4,
  5. Lars G Hemkens4,
  6. Thomas Semlitsch5,
  7. Christoph Pachler6,
  8. Reinhard Strametz1,
  9. Karl Horvath7

Editorial Group: Cochrane Hypertension Group

Published Online: 7 SEP 2011

Assessed as up-to-date: 19 MAY 2011

DOI: 10.1002/14651858.CD008274.pub2


How to Cite

Siebenhofer A, Jeitler K, Berghold A, Waltering A, Hemkens LG, Semlitsch T, Pachler C, Strametz R, Horvath K. Long-term effects of weight-reducing diets in hypertensive patients. Cochrane Database of Systematic Reviews 2011, Issue 9. Art. No.: CD008274. DOI: 10.1002/14651858.CD008274.pub2.

Author Information

  1. 1

    Goethe University, Institute for General Practice, Frankfurt am Main, Germany

  2. 2

    Medical University of Graz, EBM Review Center, Department of Internal Medicine and Institute for Medical Informatics, Statistics and Documentation, Graz, Austria

  3. 3

    Medical University of Graz, Institute for Medical Informatics, Statistics and Documentation, Graz, Austria

  4. 4

    Institute for Quality and Efficiency in Health Care (IQWiG), Cologne, Germany

  5. 5

    Medical University of Graz, EBM Review Center, Department of Internal Medicine, Graz, Austria

  6. 6

    Medical University Graz, Department of Anesthesiology and Intensive Care Medicine, Graz, Austria

  7. 7

    Medical University of Graz, Department of Internal Medicine, Division of Endocrinology and Metabolism, Graz, Austria

*Andrea Siebenhofer, Institute for General Practice, Goethe University, Theodor-Stern-Kai 7, Frankfurt am Main, 60590, Germany. andrea.siebenhofer@medunigraz.at.

Publication History

  1. Publication Status: New
  2. Published Online: 7 SEP 2011

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Abstract

  1. Top of page
  2. Abstract
  3. Plain language summary

Background

All major guidelines for antihypertensive therapy recommend weight loss. Thus dietary interventions that aim to reduce body weight might be a useful intervention to reduce blood pressure and adverse cardiovascular events associated with hypertension.

Objectives

Primary objectives

To assess the long-term effects of weight-reducing diets in hypertensive patients on

-   all cause mortality
-   cardiovascular morbidity
-   adverse events (including total serious adverse events, withdrawal due to adverse events and total non-serious adverse events)

Secondary objectives

To assess the long-term effects of weight-reducing diets in hypertensive patients on

-   change from baseline in systolic blood pressure
-   change from baseline in diastolic blood pressure
-   body weight reduction

Search methods

Studies were obtained from computerised searches of Ovid MEDLINE, EMBASE, CENTRAL and from searches in reference lists and systematic reviews.

Selection criteria

Randomised controlled trials (RCT) in adult hypertensive patients were included if they had a study duration of at least 24 weeks and compared weight reducing dietary interventions to no dietary intervention in adult patients with primary hypertension.

Data collection and analysis

Two authors independently assessed risk of bias and extracted data. Studies were pooled using fixed-effect meta-analysis. In case of moderate or larger heterogeneity as measured by Higgins I2, a random effects model was used.

Main results

Eight studies involving a total of 2100 participants with high blood pressure and a mean age of 45 to 66 years met our inclusion criteria. Mean treatment duration was 6 to 36 months. No study included mortality as a pre-defined outcome. One RCT evaluated the effects of dietary weight loss on a combined endpoint, consisting of the necessity of reinstating antihypertensive therapy and severe cardiovascular complications. In this RCT weight reducing diet lowered the endpoint, hazard ratio 0.70 (95% confidence interval [CI], 0.57 to 0.87) compared to no diet. None of the studies evaluated adverse events as designated in our protocol. Blood pressure was reduced in patients assigned to weight loss diets as compared to controls: systolic blood pressure (SBP): weighted mean difference (WMD): -4.5 mm Hg; 95% CI, -7.2 to -1.8 mm Hg (3 of  8  studies included in analysis), and diastolic blood pressure (DBP): WMD -3.2 mm Hg; 95% CI, -4.8 to -1.5 mm Hg (3 of  8  studies included in analysis). Patients' body weight was also reduced in dietary weight loss groups as compared to controls, WMD of -4.0 kg (95% CI: -4.8 to -3.2) (5 of  8  studies included in analysis). 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.

Authors' conclusions

In patients with primary hypertension, weight loss diets reduced body weight and blood pressure, however the magnitude of the effects are uncertain as a result of the small number of patients and studies that could be included in the analyses. It is not known whether weight loss reduces mortality and morbidity. No useful information on adverse effects was reported in the relevant trials.

 

Plain language summary

  1. Top of page
  2. Abstract
  3. Plain language summary

Weight reducing diets for patients with elevated blood pressure

Compared to the general population, patients with high blood pressure have a higher risk for death and complications such as heart attack or stroke. Based on the association of increased weight and increased blood pressure, dietary interventions to lower body weight are commonly recommended as a first therapeutic step for overweight patients with high blood pressure. However, whether weight loss has a long-term effect on blood pressure and reduces the adverse effects of elevated blood pressure remains unclear. As only randomised controlled trials (RCT) comparing groups with and without a weight reducing diet can answer these issues, we only included RCTs in our systematic review. 30 articles reporting on eight studies met the inclusion criteria. The 8 included studies involved a total of 2100 participants with high blood pressure and a mean age of 45 to 66 years. Mean treatment duration was 6 to 36 months and there was little or no information about deaths or other long-term complications. In three of eight studies, effects on systolic and diastolic blood pressure were provided, showing that systolic and diastolic blood pressure were reduced by weight loss interventions by 4.5 mm Hg and 3.2 mm Hg, respectively. Five out of eight studies reported body weight, and weight loss interventions reduced weight by 4.0 kg as compared to controls. No useful information on possible adverse effects was reported in the included trials.
In conclusion, there is no evidence for effects of weight loss diets on death or long-term complications and adverse events. In addition, results on blood pressure and body weight could be considered uncertain, because not all studies were included in the analyses. But these results are mainly based on one large study with about 600 participants that was judged to be of high quality, and the fact that most of the other studies excluded from analysis indirectly (e.g. via successful withdrawal of blood pressure reducing drugs) further underline these effects, gives confidence in the obtained results.