ORLANDO — A simple hypertension-treatment algorithm was more effective than was guideline-led practice for controlling blood pressure in a controlled study involving 45 family practices in southern Ontario.
The cornerstone of the algorithm was initial, low-dose treatment with a fixed-dose combination of a diuretic and an angiotensin-controlling drug. After the first 6 months of treatment, practices that used the algorithm to treat patients achieved a 65% control rate, compared with a 53% rate in practices that used standard approaches based on official Canadian recommendations, a 12% absolute difference in control that was statistically significant, Dr. Ross Feldman said at the annual scientific sessions of the American Heart Association.
“This simple, back-to-the-future, stepped-care approach may lead to better blood pressure control rates,” said Dr. Feldman, deputy scientific director at the Robarts Research Institute in London, Canada.
“Improving care by simplifying the [antihypertensive] regimen in routine clinical practice is a substantial accomplishment,” commented Dr. John Spertus, director of cardiovascular education and outcomes research at the Mid-America Heart Institute in Kansas City, Mo.
The Simplified Therapeutic Intervention to Control Hypertension (STITCH) trial randomized 45 family practices in southern Ontario. Most were single-physician practices. The physicians in 27 control practices were encouraged to manage their patients with treated but uncontrolled hypertension following guidelines from the Canadian Hypertension Education Program, recommendations that are similar to those from the Joint National Committee in the United States, Dr. Feldman said. Physicians in the 18 intervention practices were asked to manage uncontrolled hypertension by following a specific treatment algorithm. (See box.)
The average age of the 2,048 patients in the study was 62 years, and average blood pressure at the start of the study was about 154/88 mm Hg. To start treatment according to the algorithm, which called for a low dose (half tablet) of a marketed formulation that combined a diuretic with either an angiotensin-converting enzyme inhibitor or an angiotensin-receptor blocker, physicians could choose among 11 formulations that were on the Canadian market at the time the study began. Physicians in control practices could choose among more than 100 possible two-drug combinations for initial therapy based on what was on the Canadian market.
Patients were considered to have reached their goal pressure if it was less than 140/90 mm Hg, or less than 130/80 mm Hg if the patient also had diabetes.
The STITCH algorithm led to an average 22.9-mm Hg drop from baseline in systolic blood pressure, compared with an average fall of 17.2 mm Hg in the control patients, a 5.7 mm Hg absolute difference that was statistically significant. This difference in blood pressure reduction is comparable with what is often achieved by adding an additional drug to an antihypertensive regimen, Dr. Feldman noted. Diastolic pressure fell by an average of 2.4 mm Hg more in the patients treated by the STITCH algorithm, compared with control patients.
But the total number of standard drug doses received by patients in the two treatment groups was very similar, about two doses per day, indicating that patients in the algorithm group were not receiving more drugs than were control patients; they were simply receiving more effective regimens.
The major difference between the algorithm and standard-care groups was that the prespecified algorithm was simpler, Dr. Feldman said in an interview.
The STITCH algorithm had several other attractive features, commented Dr. Elijah Saunders, professor of medicine and head of the section of hypertension at the University of Maryland, Baltimore. Its simpler regimens with fewer pills for patients to take may have improved compliance. The fixed-dose combinations also reduced costs to patients by eliminating some copays, and the formulations may have improved tolerability and produced quicker blood pressure control, Dr. Saunders said.
The major limitation to using a similar strategy in the United States is that fixed-dose, combination-drug formulations of the type used in the study have not been approved by the Food and Drug Administration for initial treatment of hypertension. Despite this, “it's only a matter of time before we have support for a STITCH-like study in the United States,” Dr. Saunders said.
In Canada, Dr. Feldman said he is hopeful that the STITCH treatment algorithm can be officially endorsed by 2009, he said in an interview.
Algorithm Used In STITCH
1. Start patients on a half tablet daily of the lowest dose available for a fixed-dose combination of a diuretic plus either an angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker.
2. If patient fails to reach goal, gradually raise dose, titrating to a whole tablet daily and then progressing to higher fixed-dose combinations of the same formulation until maximum dose for formulation is reached.