Almost half of Medicare beneficiaries with high blood pressure do not take medications prescribed for their condition properly putting them at increased risk for a range of health complications.

Researchers from the U.S. Centers for Disease Control and Prevention (CDC) said that about 5 million people age 65 years and older do not manage their high blood pressure correctly and this poses concern because it can increase their risk for stroke, heart disease, kidney disease and even premature death.

In a new study published in CDC's Morbidity and Mortality Weekly Report (MMWR) on Sept. 13, Matthew Ritchey, from CDC's Division for Heart Disease and Stroke Prevention, and colleagues found that about 70 percent of adults in the U.S. who are at least 65 years old suffer from high blood pressure but almost half of these do not have their condition under control.

Researchers also found that 26.3 percent of Medicare Part D beneficiaries, which is equivalent to 4.9 million people, do not adhere to a drug regimen, which can contribute to increased likelihood for hypertension and related health conditions.

The study likewise found that the percentage of people who do not take their blood pressure medicine is higher among certain ethnic and racial groups such as Hispanics, Blacks and American Indian/Alaska Natives.

Southern U.S. states, the U.S. Virgin Islands and Puerto Rico were also found to have the highest overall rate of people who do not take their blood pressure medicine as directed.

"Although multiple factors contribute to the high proportion of uncontrolled blood pressure among persons in this age group, persons who are adherent to their antihypertensives are 45 [percent] more likely to achieve blood pressure control and have up to a 38 [percent] decreased risk for having a cardiovascular event compared with persons who are nonadherent," the researchers reported.

The study did not look at the possible reasons why many people do not adhere to their blood pressure medications but researchers have identified possible factors such as concerns over the unwanted side effects of taking these medications and complex drug regimens.

CDC director Tom Frieden, who described the findings as troubling, said that many people also have the misconception that their blood pressure is fine since they do not experience or show any symptoms.

"There's a reason hypertension is called the silent killer," Frieden said adding that many patients who have very high blood pressure feel fine until they suffer from heart attack or stroke.