https://immattersacp.org/weekly/archives/2016/09/20/1.htm

Nonadherence to antihypertensive medications common in Medicare beneficiaries

Rates of nonadherence varied by patient age, drug class, race and ethnicity, and state of residence.


More than 1 in 4 Medicare beneficiaries do not adhere to their antihypertensive drug regimen, according to a new study from the CDC and CMS.

Researchers analyzed prescription drug claims data among Medicare Advantage or Medicare fee-for-service beneficiaries 65 years of age and older with Medicare Part D coverage during 2014 who had at least 2 antihypertensive prescriptions in the same pharmacologic therapeutic class filled on different service dates within more than 90 days. The study aimed to assess antihypertensive nonadherence stratified by such factors as antihypertensive class, treatment and demographic characteristics, and type of prescription drug plan; to identify groups and regions most at risk for antihypertensive nonadherence; and to help inform targeted interventions. Results were published online Sept. 13 by Morbidity and Mortality Weekly Report.

A total of 18.5 million Medicare Part D beneficiaries were included in the study, and of these, 4.9 million (26.3%) were not adherent to their antihypertensive regimen. The researchers measured nonadherence by using the proportion of days covered (PDC), representing the percentage of days that a beneficiary had access to the prescribed medication from the date of the first filled antihypertensive prescription through 2014 or the beneficiary's 2014 death. A PDC of less than 80% was considered nonadherent. For patients taking more than 1 antihypertensive drug, overall PDC was calculated as an average of the PDCs for each therapeutic class.

Rates of nonadherence varied by drug class (range, 16.9% for angiotensin II receptor blockers to 28.9% for diuretics), race and ethnicity (24.3% for non-Hispanic whites, 26.3% for Asian/Pacific Islanders, 33.8% for Hispanics, 35.7% for blacks, and 38.8% for American Indians/Alaska Natives), and state of residence (range, 18.7% in North Dakota to 33.7% in the District of Columbia). Nonadherence rates tended to be higher in the southern U.S. than in other regions (28.9% versus 26.7% for the West, 24.1% for the Northeast, and 22.8% for the Midwest). Older patients were slightly more likely to be nonadherent (29.0% in those ≥85 years of age, 27.0% in those ages 75 to 84, and 25.4% in those ages 65 to 74), as were those taking 2 classes of antihypertensive medications versus a single class (27.2% vs. 23.3%).

The researchers noted that the PDC measure assesses only medication availability, not actual consumption; that the PDC excludes patients who filled only 1 antihypertensive prescription and patients who are prescribed medication but never take it; and that some patients may have purchased generic antihypertensive drugs directly rather than through their prescription drug plan, among other limitations. However, they concluded that based on available data, more than 1 in 4 Medicare Part D beneficiaries taking antihypertensive drugs did not adhere to their regimen, with some racial and ethnic groups and geographic areas at increased risk.

The researchers suggested several strategies for improving antihypertensive adherence in at-risk groups, including simplifying regimens, using motivational counseling techniques, maximizing use of generics, encouraging home blood pressure monitoring, and educating patients about the risks of uncontrolled blood pressure. “Although recognized as challenging, improving adherence to antihypertensives is an effective way to improve blood pressure control and reduce cardiovascular events in this population, which is already at high risk for having cardiovascular disease,” the authors wrote. They stressed that coordinated approaches are important to improving both adherence and cardiovascular health.