Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made. (Formerly, these situations were captured under a "C Recommendation".) This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade. For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.
Burden of Suffering
Estimates from several BP surveys over the past decade suggest that
up to 15% of the adult population have definite or established hypertension
and that an almost equal percentage have labile hypertension characterized
by elevations of BP on some, but not all, occasions. Epidemiological and
actuarial studies have repeatedly demonstrated that cardiovascular morbidity
and mortality are substantially higher in hypertensives, compared with
normotensives at all ages and in both sexes. Because hypertension is an
important contributor to the principal cardiovascular diseases which account
for more than 40% of all deaths in Canada, good BP control will have a
major beneficial effect on health care costs. Hypertension is a major contributor
to pressure-related events such as stroke, congestive heart failure and
ruptured aortic aneurysm, and a significant risk factor for atheromatous
complications such as coronary heart disease and occlusive peripheral arterial
disease. The absolute risk of cardiovascular disease amongst equally hypertensive
individuals varies substantially, depending upon a history of previous
cardiovascular disease or the presence of associated risk factors including
hypercholesterolemia, cigarette smoking, glucose intolerance, left ventricular
hypertrophy, older age, and male gender.
Options
Blood pressure measurement is usually done by health professionals
using mercury sphygmomanometers or by self monitoring. Nondrug treatment
of hypertension can include dietary interventions, weight reductions, reduction
of alcohol consumption, increased physical activity, and sodium restrictions.
Drug treatment of hypertension includes diuretics, b
-adrenergic blockers, calcium entry blockers, angiotensin converting enzyme
and receptor blockers, and alpha-adrenergic blockers. Drugs that are no
longer prescribed are reserpine, alpha-methyldopa, guanethidine, hydralazine,
and clonidine. Drugs that have insufficient data on long-term benefits
and risks for consideration in this guideline are calcium entry blockers,
angiotensin converting enzyme inhibitors, and alpha-adrenergic blockers.
Outcomes
Treatment outcomes include reduced blood pressure, decreased cardiovascular
events and stroke, and decreased mortality (all cause, cardiac, and noncardiac).
Evidence
MEDLINE was searched for 1966 to March 1994 using the keyword hypertension
with the subheadings complications, diagnosis, drug therapy, epidemiology,
prevention and control, and therapy and for 1984 to 1994 for review articles
on the topic. Bibliographies were also checked for relevant studies.
Values
The 13-member Task Force of experts in family medicine, geriatric medicine,
pediatrics, psychiatry and epidemiology used an evidence-based method for
evaluating the effectiveness of preventive health care interventions. Recommendations
were not based on cost-effectiveness of options. Patient preferences were
not discussed.
Background papers providing critical appraisal of the evidence and tentative
recommendations prepared by the chapter author were pre-circulated to the
members. Evidence for this topic was presented and deliberated upon in
1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993.
Consensus was reached on final recommendations.
Benefits, Harms, and Costs
The mercury sphygmomanometer is an accurate and dependable instrument
for detection of hypertension and is usually considered to be the standard
for measurement of blood pressure. Two or more readings should be averaged.
The primary definition of hypertension is diastolic blood pressure below
above 90 mmHg although in some situations such as renal disease in patients
with diabetes this minimum should be lower.
Nondrug therapies (weight reduction in overweight persons, moderation in alcohol consumption, increased physical activity, and sodium restriction) reduced blood pressure in short-term studies but no data exist to show reductions in cardiovascular mortality or morbidity. Despite the absence of evidence on long-term safety, acceptability and effectiveness of nondrug therapies, they are considered a useful starting point for treatment or important adjunct to drug therapy.
Young and middle aged patients (age 21 to 64 years) with diastolic blood pressure ³ 90 mm Hg benefit from drug therapy. High-risk patients benefit from drug therapy and low-risk patients can start with nondrug treatments.
Meta-analyses of drug therapy show that a reduction of stroke mortality in elevated diastolic blood pressure results in a 42% reduction in fatal and non-fatal strokes (95% CI 33% to 50%) and a 14% reduction in coronary heart disease (CI 4% to 22%).
Side effects of medication are substantial and in 1 trial 20% of participants in the active treatment group had stopped medication by 5 years.
Young and middle aged patients (age 21 to 64 years) with diastolic blood pressure ³ 90 mm Hg benefit from drug therapy. For high-risk patients, drug therapy is generally indicated right away, while low-risk patients can start with nondrug treatments, and progress to drug therapy, as needed.
Multifactorial intervention trials of primary prevention in high-risk
patients generally have been disappointing.
Recommendations
Recommendation grade [A, B, C, D, E] and level of evidence
[I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations
in support of individual recommendations are identified in the guideline
text.