Stroke Risk Profile Based on the Framingham Study

 

Patient selection:

(1) both male and female

(2) ages 55 – 84

(3) free of previous stroke

(4) systolic blood pressure 95 – 213 mm Hg for men and 95 – 204 mm Hg in women (The restriction on blood pressure is copied from the previous table method and may not apply to the equation method.)

 

Parameters used for risk appraisal:

(1) age in years

(2) systolic blood pressure

(3) taking antihypertensive medications (in women there is an interaction with the systolic blood pressure)

(4) diabetes mellitus

(5) cigarette smoking

(6) history of cardiovascular disease (as intermittent claudication or CHF in Table 5 and 6 footnotes; also referred to include myocardial infarction, angina pectoris and coronary insufficiency elsewhere)

(7) history of atrial fibrillation

(8) evidence of left ventricular hypertrophy on electrocardiogram (ECG)

Parameter	Finding	Points
under antihypertensive therapy	no	0
	yes	1
diabetes mellitus	no	0
	yes	1
cigarette smoking	no	0
	yes	1
history of cardiovascular disease	no	0
	yes	1
history of atrial fibrillation	no	0
	yes	1
left ventricular hypertrophy on ECG	no	0
	yes	1

 

linear function for men =

= (0.0505 * (age in years)) + (0.0140 * (systolic blood pressure in mm Hg)) + (0.3263 * (points for antihypertensive therapy)) + (0.0.3384 * (points for diabetes mellitus)) + (0.5147 * (points for cigarette smoking)) + (0.5195 * (points for cardiovascular disease)) + (0.6061 * (points for atrial fibrillation)) + (0.8415 * (points for left ventricular hypertrophy))

 

linear function for women =

= (0.0657 * (age in years)) + (0.0197 * (systolic blood pressure in mm Hg)) + (2.5432 * (points for antihypertensive therapy)) - (0.0134 * (systolic blood pressure in mm Hg if receiving antihypertensive therapy))+ (0.5442 * (points for diabetes mellitus)) + (0.5294 * (points for cigarette smoking)) + (0.4326 * (points for cardiovascular disease)) + (1.1497 * (points for atrial fibrillation)) + (0.8488 * (points for left ventricular hypertrophy))

 

where:

• The coefficients for the equations are given in Table 3 page 314.

• The handling of the "blood pressure x therapy interaction" (systolic blood pressure in mm Hg if receiving antihypertensive therapy) in women is my best guess based on Table 6. I implemented it as ((points for antihypertensive therapy) * (systolic blood pressure))

 

value for A for men =

= (linear function for men) – 5.6770

 

value for A for women =

= (linear function for women) – 7.5766

 

where:

• 5.6770 and 7.5766 are values for the linear functions using the mean values for age and systolic blood pressure and percentage of the population with a risk factor for the remaining parameters (see Table 2, page 313 and Appendix page 317).

 

value for B =

= EXP(A)

 

probability of stroke in X years =

= 1 – ((probability of survival without stroke)^(B))

 

number of years	Probability of Survival Without Stroke in Men	Probability of Survival Without Stroke in Women
1	0.9948	0.9977
2	0.9889	0.9920
3	0.9826	0.9864
4	0.9740	0.9802
5	0.9642	0.9741
6	0.9551	0.9665
7	0.9422	0.9584
8	0.9270	0.9509
9	0.9144	0.9448
10	0.9044	0.9353