Pretest variables that improve the predictive value of exercise testing in women

Graded exercise testing (GXT) is used in coronary artery disease (CAD) prevention and rehabilitation programs. In women, this test has a decreased accuracy and predictive value but there are few studies that examine the predictors of a verified positive test. The aim of this study was to determine those pretest variables that might enhance the predictive value of the GXT in women clients.

Medical records of 1761 patients referred for GXT's over a 5 yr period of time were screened. Demographic, medical, and exercise test variables were analyzed. The GXT's of 403 women were available for inclusion and they were stratified into 3 groups: positive responders that were subsequently shown to have CAD (N.=28 verified positive [VP]), positive responders that were not shown to have CAD (N.=84 non-verified positive [NVP]) and negative GXT responders (N.=291). Both univariate and a multivariate step-wise regression statistics were performed on this data.

Pretest variables that differentiated between VP and NVP groups are: (an older age=65.8 vs. 60.2 yrs. P<0.05; a greater BMI=30.8 vs. 28.8 kg/m2; diabetes status or an elevated fasting glucose =107.4 vs. 95.2 mg/dL P<0.05; and the use of some cardiovascular medications. Our subsequent linear regression analysis emphasized that HDL cholesterol and beta blocker usage were the most predictive of a positive exercise test in this cohort.

The American Heart Association recommends GXT's in women with an intermediate pretest probability of CAD. But there are only two clinical variables available prior to testing to make this probability decision: age and quality of chest pain. This study outlined that other pre-exercise test variables such as: BMI, blood chemistry (glucose and lipoprotein levels) and the use of cardiovascular medications are useful in clinical decision making. These pre-exercise test variables improved the predictive value of the GXT's in our sample.