A large study suggests that a long-used type of blood pressure medicine may be a better first treatment for many patients than one of the most commonly prescribed alternatives.
Researchers found that thiazide-type diuretics were linked to fewer major heart problems than ACE inhibitors in people beginning treatment for high blood pressure.
High blood pressure is extremely common and often causes no symptoms. Over many years, however, it can damage blood vessels and raise the risk of heart attack, stroke, heart failure, kidney disease and other serious problems.
Doctors have several types of medicines available to lower blood pressure. Common choices include ACE inhibitors, thiazide or thiazide-like diuretics, angiotensin II receptor blockers, known as ARBs, and calcium channel blockers.
These medicines lower blood pressure in different ways. ACE inhibitors relax blood vessels by blocking a body system that normally causes vessels to tighten, while thiazide diuretics help the kidneys remove extra salt and water and also reduce pressure in the blood vessels.
Researchers led by Columbia University examined health information from nearly 5 million patients across several countries. The patients had recently started medicine for high blood pressure and had no previous treatment recorded in the study data.
The researchers compared nine commonly used blood pressure medicines and looked at how well they prevented major health problems. They also examined a wide range of possible side effects.
ACE inhibitors were the most common starting treatment, prescribed to about 48% of patients. Thiazide or thiazide-like diuretics were used first in only about 17%.
Yet the results favored the diuretics in several important areas. Compared with ACE inhibitors, thiazide or thiazide-like drugs were associated with about a 15% lower risk of heart attack, hospitalization for heart failure or stroke.
The safety results also raised questions about the widespread use of ACE inhibitors as the first choice. The researchers found differences in numerous side effects, with thiazide-type drugs showing a better overall safety profile in the comparison.
ACE inhibitors are already known to cause certain problems in some patients, including a persistent dry cough. They can also affect kidney function and potassium levels, which is why doctors may use blood tests to monitor people taking them.
The researchers estimated that if the people who started ACE inhibitors had instead received a thiazide-type diuretic, more than 3,100 major cardiovascular events might have been avoided. This estimate was based on the patterns seen in the large collection of patient records.
However, the findings do not mean ACE inhibitors are poor medicines or that everyone should switch treatments. ACE inhibitors remain valuable for many patients and may be particularly useful when other medical conditions influence the choice of blood pressure drug.
The study was observational, meaning researchers analyzed existing health records rather than randomly assigning every patient to a medicine. This type of research can reveal important real-world patterns, but it cannot prove with complete certainty that one drug directly caused better outcomes.
The research, led by Dr. George Hripcsak and colleagues at Columbia University Irving Medical Center, was published in The Lancet in 2019. It used a large international research network to compare the effectiveness and safety of medicines commonly recommended as first treatments for high blood pressure.
For patients, the findings are not a reason to stop or change blood pressure medicine without medical advice. Instead, they give doctors more evidence to consider when choosing a first treatment, while factors such as age, kidney health, other illnesses and possible side effects remain important in deciding which medicine is best for each person.
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