Stroke: diastolic blood pressure =100 mmHg increased risk of stroke.

Clinical bottom line (level 1a)

  1. Patients over 25 years old are at an increased risk of stroke or coronary heart disease within 10 years if they have baseline diastolic blood pressure of 100 mmHg or more.
  2. Patients are at a decreased risk of stroke or coronary heart disease if they have a baseline diastolic blood pressure of 89 mmHg or less.
MacMahon et al: Lancet 1990; 335: 765-774
Expires June 2003

The study

Prospective cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: collaboration of nine prospective observational studies, North America, Europe, Puerto Rico and Hawaii

418343 patients (aged range 25 to 84 years, 96% male) not recorder as having had a stroke or MI before the baseline visit and had not been receiving treatment for diabetes mellitus

Excluded if
  • aged <25 years



    • Factors studied:
  • stroke
  • baseline diastolic blood pressure = 79 mmHg
  • baseline diastolic blood pressure 80-89 mmHg
  • baseline diastolic blood pressure 100-109 mmHg
  • baseline diastolic blood pressure = 110 mmHg
  • baseline diastolic blood pressure = 79 mmHg
  • baseline diastolic blood pressure 80-89 mmHg
  • baseline diastolic blood pressure 100-109 mmHg
  • baseline diastolic blood pressure = 110 mmHg




    • Cox proportional hazards model was used to adjust for confounding factors.

    range 6 to 25 years followed for mean 10 years
    Outcomes studied:
  • stroke
  • coronary heart disease

    • Age, blood cholesterol and smoking were the confounding factors adjusted for.

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    stroke mean 10 years 843/418343 0.20%
    (0.19% to 0.22%)
    coronary heart disease mean 10 years 4856/422592 1.15%
    (1.12% to 1.18%)

    prognostic factor for
    stroke     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    baseline diastolic blood pressure = 79 mmHg mean 10 years 0.35
    (0.30 to 0.40)     		-615
    (-677 to -571)
    baseline diastolic blood pressure 80-89 mmHg mean 10 years 0.60
    (0.45 to 0.68)     		-962
    (-1202 to -699)
    baseline diastolic blood pressure 100-109 mmHg mean 10 years 1.80
    (1.60 to 2.00)     		694
    (556 to 926)
    baseline diastolic blood pressure = 110 mmHg mean 10 years 3.60
    (3.00 to 4.00)     		214
    (185 to 278)

    prognostic factor for
    coronary heart disease     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    baseline diastolic blood pressure = 79 mmHg mean 10 years 0.45
    (0.37 to 0.50)     		-133
    (-146 to -116)
    baseline diastolic blood pressure 80-89 mmHg mean 10 years 0.70
    (0.60 to 0.75)     		-271
    (-325 to -203)
    baseline diastolic blood pressure 100-109 mmHg mean 10 years 1.50
    (1.40 to 1.60)     		187
    (156 to 234)
    baseline diastolic blood pressure = 110 mmHg mean 10 years 2.20
    (2.00 to 2.40)     		76
    (66 to 92)

    Comments

    1. There was no significant heterogeneity between the studies pooled.

    Citation

    1. MacMahon S, Peto R, Cutler J, et al: Blood pressure, stroke, and coronary heart disease: Part 1, prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias. Lancet 1990; 335: 765-774
    Contributor: Clare Wotton and Musab Hayatli, December 1999
    Reviewer:

    Clinical Question.
    Patient no previous stroke or MI
    Intervention or Exposure diastolic blood pressure
    Outcome stroke or coronary heart disease