Predicting Claudication Pain Using Equations

 

Clinical data collected:

(1) systolic blood pressure at ankle while at rest

(2) systolic blood pressure of brachial artery while at rest

(3) laterality of vascular involvement

(4) gender of the patient

Parameter	Finding	Points
laterality	unilateral	1
	bilateral	2
gender	female	1
	male	2

 

estimated walking distance in meters before onset of claudication =

= 159.9 – (321.8 * (ankle systolic pressure in mm Hg) / (brachial systolic pressure in mm Hg)) + (445.6 * (((ankle systolic pressure) / (brachial systolic pressure))^2)) – (93.5 * (points for laterality)) + (99.0 * (points for gender))

 

estimated walking distance in meters to maximal claudication pain =

= 83.1 + (195.0 * (ankle systolic pressure in mm Hg) / (brachial systolic pressure in mm Hg)) + (174.0 * (((ankle systolic pressure) / (brachial systolic pressure))^2)) – (76.4 * (points for laterality)) + (114.2 * (points for gender))

 

Limitations:

• The R^2 for the equations are 0.53 and 0.55 (adjusted). The SEE for the onset equation is 110.5 and the SEE for the maximal pain is 138.3. This means that 95% of patients will have experience claudication within a distance 221 and 277 meters of the predicted values. If the distance predicted is short (< 100 m) then the actual value might be 2-3 times the value predicted (see page 169).