A nomogram of exercise capacity for age predicted mortality in women with cardiovascular symptoms.

M e t h o d s Design: 2 cohort studies, 1 for derivation of a nomogram (St. James Women Take Heart Project [SJWTHP]) and 1 for validation (Economics of Noninvasive Diagnosis Study [ENDS]). Setting: Metropolitan Chicago (SJWTHP) and 6 medical centers in the United States (ENDS). Patients: The derivation cohort included 5721 women ≥ 35 years of age (mean age 52 y) with the ability to walk on a treadmill at a moderate pace, weight ≤ 148 kg, and blood pressure < 170/110 mm Hg. Exclusion criteria included pregnancy, typical angina symptoms, history of cardiac disease, and incomplete data on cardiac risk factors. The validation cohort included 4471 women (mean age 61 y) with cardiovascular symptoms. Women who were recently hospitalized for unstable angina, myocardial infarction, or coronary revascularization were excluded. Description of prediction guide: For all participants, exercise capacity (measured in metabolic equivalents [METs]) was estimated based on the speed and grade of a treadmill according to the Bruce protocol. Through use of the derivation cohort, a linear regression of exercise capacity on age was calculated as MET = 14.7 – 0.13 × age. For a given age, the percentage of predicted exercise capacity was obtained from (observed METs ÷ agepredicted METs) × 100. A nomogram to determine the percentage of predicted exercise capacity for age was constructed using the linear regression equation for the deviation cohort. The association between exercise capacity and mortality was assessed using Cox proportional-hazards models. Outcome: All-cause and cardiac mortality.