Poor adherence to hypertension drugs may raise stroke risk

Patients with high BP who do not adhere to their antihypertensive medication are at increased risk for stroke and stroke-related mortality compared with patients who follow their drug regimen, according to findings in a new report.

In the study of more than 73,500 hypertensive patients, those who did not adhere to their medication had a nearly fourfold higher risk for stroke-related mortality in the second year after being prescribed antihypertensive medication and a threefold higher risk in the 10th year of medication prescription compared with adherent patients (OR=3.81, 95% CI, 2.85-5.1; OR=3.01; 95% CI, 2.37-3.83, respectively). Hospitalization due to stroke also was higher among nonadherent patients at 2-year follow-up (OR=2.74; 95% CI, 2.35-3.2) and 10-year follow-up (OR=1.71; 95% CI, 1.49-1.96).

In the year that nonadherent patients died of a stroke, their risk for mortality was 5.7-fold higher (OR=5.68; 95% CI, 5.05-6.39) and risk for hospitalization was 1.9-fold higher (OR=1.87; 95% CI, 1.72-2.03) compared with adherent patients, according to a press release.

Researchers also examined stroke risk based on adherence to specific classes of antihypertensive medication. Among patients assigned drugs that act on the renin-angiotensin system combined with diuretics or beta-blockers, nonadherence was associated with a 7.5-fold higher risk for mortality (OR=7.49; 95% CI, 5.62-9.98) and nearly fourfold higher risk for hospitalization (OR=3.91; 95% CI, 3.23-4.75) in the year that these events occurred vs. patients who took their medications correctly.

According to the researchers, associations between nonadherence and stroke risk followed a dose-response pattern — the poorer the adherence, the greater the risk for mortality and hospitalization due to stroke.

Evidence that degree of nonadherence affected risk was found when researchers examined patients who adhered correctly to their medication more than 80% of the time compared with patients with intermediate (30% to 80%) and poor adherence (<30%). In the year that a fatal or nonfatal stroke occurred, patients in the intermediate and poor adherence groups had a 1.7-fold and 2.6-fold higher risk for nonfatal stroke and 3.6-fold and eightfold higher risk for fatal stroke, respectively, compared with patients with good adherence, according to the release.

Researchers used nationwide registers in Finland to analyze data on prescriptions, hospital admissions and deaths. They tracked number of prescriptions per year to determine patient adherence to antihypertensive medication. Information on patient medication purchases was available from 1995 and the researchers followed patients from 1995 to 2007. During this time, of the 73,527 patients aged 30 years or older, 2,144 died of stroke and 24,560 were admitted to the hospital with a stroke.

“As far as we know, this study is unique as it is the first study to follow patients over a long period of time, repeatedly checking how correctly they are taking their medications, and linking the trajectory of adherence with the risk of fatal and nonfatal stroke,” Kimmo Herttua, senior fellow in the population research unit at University of Helsinki, Finland, stated in the press release.

“These results emphasize the importance of hypertensive patients taking their antihypertensive medications correctly in order to minimize their risk of serious complications such as fatal and nonfatal strokes.”

For more information:

Herttua K. Eur Heart J. 2013;doi:10.1093/eurheartj/eht219.

Disclosure: The researchers report no relevant financial disclosures.