More people are heading to hospital emergency departments with high blood pressure, but some visits may be unnecessary, a new study shows.

Visits to emergency departments for patients with high blood pressure, known also as hypertension, increased by 64 percent between 2002 and 2012 while hospitalizations for those visits declined by 28 percent, according to the new Canadian study.

Patients who are unnecessarily alarmed by the reading on their home blood pressure monitors may spur some of these visits, the researchers theorize.

During the study period in which visits to Ontario emergency departments for hypertension increased from 15,793 to 25,950 per year, the proportion of patients admitted to the hospital as a result decreased from 9.9 percent to 7.1 percent, the study showed.

Among the patients whose emergency department visit ended in admission to the hospital, the most frequent hospital diagnoses were stroke, renal failure and heart failure. The proportion of patients arriving via ambulance increased over time, from 10.7 percent to 14.3 percent.

Mortality was very low: less than one percent of patients died within 90 days and only 4.1 percent died within two years. Together, hospitalizations for stroke, heart failure, acute myocardial infarction, atrial fibrillation, renal failure, hypertensive encephalopathy and aortic dissection were less than one percent at 30 days.

"Stroke remains a huge killer and we do appreciate patients with hypertension being so conscientious about monitoring their readings," says Dr. Clare Atzema, lead author of the study, which appears in Annals of Emergency Medicine.

"Patients should be aware that unless their high blood pressure coincides with symptoms of a medical emergency, such as chest pain, severe headache, nausea or shortness of breath, they probably do not need to visit the ER,” she says.

“We of course encourage them to follow up as soon as possible with their regular physician. If there is any doubt, come to the emergency department: we would rather have you come without an emergency than stay home with one,” Atzema added.