High blood pressure and diabetes: big gaps in knowledge regarding non-drug treatment strategies

Stress, smoking and high alcohol consumption damage health, whereas a healthy diet and regular physical activity are helpful. These medical recommendations also apply to people with high blood pressure or diabetes, but to date there is no scientific proof as to whether and to what extent people with these conditions especially benefit from changes in lifestyle or a specific reduction in blood pressure.

This is due to the fact that despite the substantial epidemiological importance of high blood pressure and diabetes, the benefit of non-drug treatment strategies in particular has not been adequately investigated. These are the conclusions from the results of 6 reports (rapid reports) published on 19th July 2012 by the German Institute for Quality and Efficiency in Health Care (IQWiG).

Comprehensive set of commissions now completed

The 6 now published reports complete a set of 10 commissions awarded by the Federal Joint Committee (G-BA) on different non-drug treatment strategies for essential hypertension and diabetes.

A total of 7 reports were concerned with non-drug treatment strategies for essential hypertension, which is the most common form of high blood pressure and has no underlying medical cause. Reports on the benefit of a reduction in salt intake, weight reduction and physical activity for patients with high blood pressure have already been published. Results of the other reports on the benefit of special diets (the Dietary Approaches to Stop Hypertension, or DASH diet), stress-coping interventions, cessation of smoking, and a reduction in alcohol consumption are now available.

On the subject of diabetes, a report has already been published on the benefit of lowering blood glucose to near-normal levels in people with type 2 diabetes. IQWiG has now published the report on the benefit of physical activity in patients with type 2 diabetes and the report on a long-term reduction in blood pressure to a target value lower than the standard levels (140 and/or 90 mmHg) in both forms of diabetes.

Difficult to draw any conclusions about benefit from the studies

To date there has been no scientific proof that, by coping with stress, stopping smoking, reducing high alcohol consumption, or eating special diets, especially patients with high blood pressure can live longer, have fewer heart attacks and strokes, are able to permanently lower their blood pressure or improve their quality of life.

There is also no proof that, by increasing their physical activity, people with type 2 diabetes can normalize their blood glucose levels, live longer and prevent late complications such as kidney failure, amputations or blindness.

The available studies provide only a limited answer to the question whether diabetes patients benefit from a reduction in blood pressure to levels in the lower normal range.

Evidence is inadequate

After evaluating the literature available worldwide, IQWiG determined that the evidence on these research questions is inadequate. If available at all, the studies consider hardly any patient-relevant outcomes. In addition, the study groups are often too small and the duration of studies too short to derive robust conclusions. Some results, for example from studies carried out in the 1970s and 1980s on coping with stress, are only applicable to a limited extent to life today. Furthermore, many study results are subject to bias and therefore cannot be clearly interpreted.

A healthy lifestyle also recommended for people with high blood pressure and diabetes
"The lack of evidence does not mean that the interventions we assessed generally have no impact on health", explained IQWiG Director Jürgen Windeler. "Naturally, the same general medical knowledge for everyone else also applies to people with essential hypertension and diabetes: being greatly overweight, having high blood pressure, smoking and drinking too much alcohol put a strain on the body and damage health". Research into stress has proved that stressful life situations can damage health in the long term. On the other hand, a balanced diet and adequate physical activity can promote health.

Better standards for studies on non-drug treatment strategies

High-quality studies are routinely conducted for drug treatments, but no regulatory procedures and therefore no clear requirements exist for non-drug forms of therapy. In IQWiG's opinion, there is an urgent need for high-quality and long-term studies on non-drug treatment strategies as well, focussing on patient-relevant outcomes. It has already been shown that such studies are possible.

"What has long been the standard for drug research must also finally become a matter of course for non-drug treatment strategies: randomized controlled trials (RCTs) with patient-relevant outcomes, larger study groups and longer time periods", urged Jürgen Windeler. "That applies especially to common conditions with a considerable burden of disease such as diabetes and high blood pressure. Here it is absolutely essential that more reliable knowledge beyond drug treatments is obtained in order to improve the quality of patient care", said Windeler. Even in drug trials, deficits remain - as shown by the report on reducing blood pressure to levels in the lower normal range in patients with diabetes. Although drugs are used to treat type 1 diabetes, here too, few studies are available.

Procedure of report production

The Federal Joint Committee (G-BA) commissioned IQWiG to prepare the report in an accelerated process, known as a "rapid report". Unlike the normal procedure, no preliminary reports are published in this case. Although a draft version of the report is reviewed by external experts, no hearing at which all interested parties can comment takes place. The published reports were compiled in collaboration with external experts and sent to the contracting agency between August 2011 and June 2012.

You can find out more about the results of the individual reports from the extension of the press release.

Contact: Tel. +49 (0)221 - 35685-0, presse@iqwig.de