Report of the Canadian Hypertension Society Consensus Conference: 4. Hypertension in the elderly

Table 1: Levels of evidence for rating studies of treatment, prevention and quality assurance

I. A randomized controlled trial (RCT) that demonstrates a statistically significant difference in at least one important outcome -- e.g., survival or major illness.

OR

If the difference is not statistically significant, an RCT of adequate sample size to exclude a 25% difference in relative risk with 80% power, given the observed results.

II. An RCT that does not meet the level I criteria.

III. A nonrandomized trial with contemporaneous controls selected by some systematic method (i.e., not selected by perceived suitability for one of the treatment options for individual patients).

OR

Subgroup analysis of a randomized trial.

IV. A before-after study or case series (of a least 10 patients) with historical controls or controls drawn from other studies.

V. Case series (at least 10 patients) without controls.

VI. Case report (fewer than 10 patients).
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Table 2: Grading system for recommendations

A. The recommendation is based on one or more studies at level I.

B. The best evidence available was at level II.

C. The best evidence available was at level III.

D. The best evidence available was lower than level III and inclued expert opinion.

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Table 3: Recent randomized controlled trials of treatment for hypertension in elderly patients*
Trial and date of published report
Variable SHEP[8]
June 1991
(n=4736) 		STOP-H[9]
Nov. 1991
(n=1627) 		MRC[10]
Feb. 1992
(n=4396)
Age, yr (mean) 60+ (72) 70-84 (76) 65-74 (70)
Entry criteria, mm Hg
  Systolic BP 160-219 180-230 160-209
  Diastolic BP less than 90 90-120++ less than 115
Mean BP on entry 170/77 195/102 184/91
Initial treatment Chlorthalidone HCTZ + amiloride, atenolol, metoprolol, pindolol HCTZ + amiloride
or atenolol
(randomized)
BP reduction, mmHg (v. placebo) 11/3 20/8 15/6
Mean length of follow-up, yr 4.5 2.1 5.8
Relative risk reduction, %
Diuretic ß-blocker
  All cardiac events~ 27# 13 44#      3^
  All CVA 36# 47# 31#       18
  All deaths 13 43# 16       -8||
* SHEP = Systolic Hypertension in the Elderly Program, STOP-H = Swedish Trial in Old Patients with Hypertension, MRC = (British) Medical Research Council (Trial), BP = blood pressure, HCTZ = hydrochlorothiazide, CVA = cerebrovascular accidents.
+ Consisted predominantly of coronary heart disease.
++ Patients with a systolic pressure of less than 180 mm Hg were also included if their diastolic pressure was 106 to 120 mm Hg.
# Significantly greater risk reduction than with placebo.
^ Significant difference between drug classes.
|| The relative risk increased (nonsignificantly) with ß-blocker treatment.
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