From 2006 to 2013, the incidence of hypertensive emergency in U.S. emergency departments more than doubled, according to an epidemiological analysis. However, hypertensive emergency was rare and occurred in 1,670 per million adults emergency department visits in 2013.

The researchers defined hypertensive emergency as a diagnosis of acute hypertension, a diagnosis indicating acute target organ damage and an admission to the hospital, death or transfer to another facility.

Lead researcher Alexander T. Janke, MD, of Wayne State University in Detroit, and colleagues published their results online Dec. 5 in the Journal of the American Heart Association.

“While markedly elevated [blood pressure] at presentation to the [emergency department] is quite common, occurring in nearly 20 percent of patients, the likelihood that it represents a true hypertensive emergency may be lower than previously thought,” the researchers wrote.

For this study, the researchers analyzed the Nationwide Emergency Department Sample, a publicly available database maintained by the Healthcare Cost and Utilization Project and funded by the Agency for Healthcare Research and Quality. In 2013, the database included information from 947 hospitals in 30 states, accounting for approximately 20 percent of hospital-based emergency department visits.

The researchers found that the incidence of emergency department visits with a diagnosis of acute hypertension increased from 170,340 in 2006 to 496,894 in 2013. During that same time period, the number of emergency department visits for acute hypertension that also carried a diagnosis for acute target organ damage increased from 65,925 to 188,696, while the number of emergency department visits for acute hypertension that also included an admission, death in the emergency department or transfer to another facility increased from 63,406 to 398,506.

During the study, hypertensive emergencies increased by 16.2 percent per year, while the number of emergency department visits increased by 2 percent per year. Meanwhile, the incidence of hypertensive emergencies increased from 677 per million adult emergency department visits in 2006 to 1,640 per million adult emergency department visits in 2013.

The change in the incidence of hypertensive emergency was statistically significant even after adjusting for payer, income, age and sex.

The incidence of hypertensive emergency visits that resulted in death in the emergency department or during the following hospital admission decreased from 4.8 percent in 2006 to 4.5 percent in 2013.

Adults who had hypertensive emergency in 2013 had a median age of 66 years old, while 54.5 percent were female, 63.0 percent were on Medicare and 39.7 percent lived in zip codes with average income in the bottom quartile. Meanwhile, the median total emergency department charges among visits for hypertensive emergency increased from $956 in 2006 to $1,800 in 2013.

The researchers mentioned a few limitations of the study, including that they did not know whether hypertensive emergencies resulted in management that included rapid lowering of blood pressure. The database also did not include information on blood pressure, laboratory values and demographic data such as race and ethnicity.

“In general, hypertensive emergency is an imprecise clinical diagnosis, and this study is fundamentally limited for that reason,” the researchers wrote. “Well‐defined clinical criteria in a large prospective study would be necessary to make a more precise statement about incidence, though even then there would be important limitations.”