Hypertension: Which drugs are best at preventing complications?

People with hypertension have an increased risk of cardiovascular disease. Drugs designed to work against high blood pressure can lower this risk. Compared with the different drug classes, diuretics can usually be seen as the first line treatment. Which drug is then used in an individual case will also depend on other aspects, for example whether someone has other diseases.

Hypertension (high blood pressure) means that the blood vessels are literally under too high a pressure. This condition does not necessarily cause noticeable symptoms. Yet over the years, high blood pressure can damage the heart and the blood vessels and lead to cardiovascular disease, including first and foremost heart attacks and strokes, as well as heart or kidney failure.

In Germany, about half of all adults have high blood pressure – and it is somewhat more common in men than in women. People are considered to have a high blood pressure if for at least two measurements taken on different days the upper measurement (systolic blood pressure) is over 140 mm Hg or the lower measurement (diastolic blood pressure) is over 90 mm Hg. Most people who have hypertension have what is called essential hypertension. This means that no other disease can be found to be causing the increase in blood pressure.

Options for lowering blood pressure

There are different options available for lowering blood pressure in the long term. Recommendations include doing sports, drinking less alcohol, not smoking, eating a balanced and low-salt diet and doing something to reduce stress. You can find out about how weight loss can affect your blood pressure here, and you can read about whether it is worth it to reduce your salt intake here.

People who cannot get their blood pressure down enough by following non-drug strategies also have the option of taking medication to help with this. There are several classes of drugs designed to lower blood pressure (also called antihypertensive drugs or simply antihypertensives). These are (in alphabetical order):

• ACE inhibitors (short for angiotensin-converting enzyme inhibitors)
• angiotensin II antagonists
• beta blockers
• calcium antagonists
• diuretics (for treating high blood pressure, thiazide diuretics are the most commonly used)

One drug taken alone is enough to lower blood pressure sufficiently in many people. But others will need a combination of two or more drugs for treatment to be successful.

Trials comparing different antihypertensive drugs

The German Institute for Quality and Efficiency in Health Care (IQWiG) – who publish this website – studied what the comparative advantages and disadvantages of different antihypertensive drugs were. To do this they searched for trials on this topic together with researchers from the University of Graz (Austria) and then summarized and analyzed the results. The researchers only used randomized controlled trials in their evaluations because they provide the most reliable results. You can find out more about these types of trials here. In total, the researchers were able to evaluate 16 trials involving about 93,000 participants. These trials lasted between two and eight years.

In most of the trials, participants were between 50 and 70 years old. There were some differences between the groups of people in the different trials however: Mostly people with diabetes participated in some trials, for example. There were equal numbers of men and women in the trials. Where enough data was available, the researchers checked whether factors like sex, diseases such as diabetes, or ethnicity influenced the benefit from the drugs.

The researchers were mostly interested in how well the various antihypertensives were able to lower the risk of heart attack, stroke and heart failure, and raise life expectancy. They also analyzed other aspects such as the risk of kidney failure and consequences for quality of life. Not all of the drugs were directly compared with one another in these trials. Yet it was possible to make conclusions about the advantages and disadvantages for many of the drug classes. Read on to find out about the most important results.

Diuretics are better than calcium antagonists

Diuretics and calcium antagonists are the best-studied drug classes. The results of these trials show that, overall, diuretics are able to prevent complications of hypertension better than calcium antagonists. Several trials in fact show that they protect against heart failure better than calcium antagonists do. There is also some evidence that diuretics are also superior to ACE inhibitors, in terms of preventing heart failure.

What is more, taking diuretics seems to prevent strokes in people with black skin color better than do ACE inhibitors. Trials comparing diuretics and beta blockers show no clear difference between these two drug classes. There are no trials directly comparing diuretics with angiotensin II antagonists.

Comparing ACE inhibitors with calcium antagonists

Comparing ACE inhibitors with calcium antagonists produced mixed results: Three trials show that ACE inhibitors prevent heart failure better than calcium antagonists, and one trial indicates that ACE inhibitors protect people with type 2 diabetes from having a heart attack better than calcium antagonists. Yet for strokes there are indications that calcium antagonists have advantages over ACE inhibitors in men with black skin color and women: in that trial people from these groups had fewer strokes when they had taken calcium antagonists.

Comparing ACE inhibitors with beta blockers

Two trials compared ACE inhibitors with beta blockers. Participants in one of these trials were exclusively people with black skin color. This trial indicated that those who took an ACE inhibitor rated their quality of life higher than did those who took a beta blocker. The second trial comparing ACE inhibitors and beta blockers included mostly people with white skin color who had type 2 diabetes. In this trial there was no difference between the two drugs. In terms of complications, there are no differences in either of the trials between ACE inhibitors and beta blockers.

Comparing angiotensin II antagonists with beta blockers

One trial compared an angiotensin II antagonist with a beta blocker. This trial had two important findings: Angiotensin II antagonists can probably lower the likelihood of developing heart failure considerably more than beta blockers can. And for people who have type 2 diabetes, life expectancy might rise if they take an angiotensin II antagonist instead of a beta blocker. This trial also indicated that angiotensin II antagonists prevent strokes better than beta blockers – with one exception: people with black skin color most likely profit more in terms of their risk of stroke from beta blockers than from angiotensin II antagonists.

Comparing angiotensin II antagonists with calcium antagonists

There were only two trials comparing angiotensin II antagonists and calcium antagonists. They show no clear advantage for either of the drugs: while there are some indications that angiotensin II antagonists protect against heart failure better than calcium antagonists, calcium antagonists might prevent heart attacks somewhat better than angiotensin II antagonists.

Antihypertensive drugs can have adverse effects

All antihypertensive drugs can have adverse effects: For example, ACE inhibitors can cause dry cough. Especially when they are first taken, calcium antagonists sometimes cause headaches or water retention (edema). Beta blockers can sometimes lead to sexual dysfunction and other problems. Angiotensin II antagonists led to some people experiencing back pain in the trials.

One adverse effect of diuretics is that the body excretes more potassium, which can lead to problems like fatigue or muscle weakness and is held responsible for an increase in some patients’ blood sugar levels. The loss of potassium can be compensated for by also taking either potassium supplements or what are called potassium-sparing diuretics. Potassium-sparing diuretics lower blood pressure only slightly, but can reduce the loss of potassium if they are taken in addition to other diuretics. The doctor may recommend checking the blood potassium levels regularly if other drugs such as ACE inhibitors are being used, for example.

Most adverse effects of antihypertensive drugs go away with time or disappear after stopping use of the medication.

The choice of drug depends on different factors

Diuretics, mostly the thiazides, are together with calcium antagonists the drugs that have been studied best in trials. Diuretics can prevent complications of hypertension better than some of the other antihypertensives. For this reason, these medications are typically viewed as first line therapy for hypertension. Yet there are a number of aspects that play a part in choosing which drug to take, for example age or whether there are other diseases, or complications such as heart failure. Sex or ethnicity can also be important when selecting a drug.

Antihypertensive drugs must be taken regularly to have a benefit

If you have high blood pressure and decide to take a drug to work against it, it is not only important that you find the medication that is best for you. You will also have to take it regularly for it to have an effect. Taking medication every day for a long time is not always an easy thing to do – especially if you do not even feel sick at all. You can quickly lose track of them, particularly if you are taking different medications for several different conditions.

If you have difficulties using your medication over the long term there are different strategies you can follow. The most helpful points are going to the doctor on a regular basis, staying well informed about your medication, and keeping your schedule for taking your drugs as simple as possible. You can find out more about this and also print out a medication chart to fill out yourself here.

Author: Institute for Quality and Efficiency in Health Care (IQWiG)

Note

This health information is a summary of a scientific report published by IQWiG. It is not an assessment of the right to have health care services paid for by statutory health insurance funds in Germany. By law, decisions about paying the costs for diagnostic and therapeutic procedures can only be made by the German Federal Joint Committee (G-BA). The Federal Joint Committee takes IQWiG reports into consideration in its decision-making process. You can find information about the decisions of the German Federal Joint Committee on its English-language website, www.english.g-ba.de.

© IQWiG (Institute for Quality and Efficiency in Health Care)