Plasma renin activity helps predict response to antihypertensive medications

Plasma renin activity along with pretreatment blood pressure can help predict a patient's response to atenolol and hydrochlorothiazide both as monotherapy and add-on therapy for primary hypertension, according to a new study.

Researchers looked at predictors of blood pressure response to therapy with atenolol followed by hydrochlorothiazide or vice versa in 363 men and women 65 years of age or younger who had primary hypertension. One hundred fifty-two patients were black, and 211 were white. Most (76%) stopped taking previous antihypertensive drugs before beginning the study regimens, and the remainder (24%) had not previously been treated for hypertension. Patients were randomly assigned to receive one of the following regimens:atenolol, 50 mg/d, titrated to 100 mg/d if blood pressure remained above 120/70 mm Hg, followed by hydrochlorothiazide, 12.5 mg/d, titrated to 25 mg/d similarly orhydrochlorothiazide, 12.5 mg/d, titrated to 25 mg/d if blood pressure remained above 120/70 mm Hg, followed by atenolol, 50 mg/d, titrated to 100 mg/d similarly.

Patients measured their average blood pressure at home before and after each study drug was administered using a study-provided sphygmomanometer. They were told to check their blood pressure while seated twice after getting out of bed in the morning and twice at night right before going to bed. Blood pressure readings were also recorded in a physician's office on patients' home machines during study visits (before randomization, after monotherapy and before the add-on drug was started, and after add-on therapy concluded). The study results were published early online Aug. 19 by American Journal of Hypertension.

The authors found that plasma renin activity and blood pressure before treatment consistently predicted patients' systolic and diastolic responses to the study drugs, both as monotherapy and as add-on therapy. Patients with higher plasma renin activity had a larger response to atenolol and a smaller response to hydrochlorothiazide, independent of age, race or other characteristics. Based on their results, the authors wrote, measuring plasma renin activity and blood pressure before add-on treatment with atenolol and hydrochlorothiazide can help predict degree of response in patients with primary hypertension. However, "whether marginal benefits demonstrated relative to hypertension specialists' care or as demonstrated in our study relative to race and age outweigh costs may be arguable," they concluded.