Prognostic value of treadmill exercise testing in elderly persons

Background: Recent exercise testing guidelines recognized a gap in knowledge about the prognostic value of treadmill exercise testing in elderly persons. Objective: To test the hypothesis that treadmill exercise testing has equal prognostic value among elderly (≥65 years of age) and younger (<65 years of age) persons and to examine the incremental value of this testing over clinical data. Design: inception cohort with a median follow-up of 6 years. Setting: Olmsted County, Minnesota. Patients: All elderly (n = 514) and younger (n = 2593) residents of Olmsted County who underwent treadmill exercise testing between 1987 and 1989. Measurements: Overall mortality and cardiac events (cardiac death, nonfatal myocardial infarction, and congestive heart failure). Results: Compared with younger patients, elderly patients had more comorbid conditions, achieved a lower workload (6.0 and 10.7 metabolic equivalents; P < 0.001), and had a greater likelihood of a positive exercise electrocardiogram (28% and 9%; P<0.001). With median follow-up of 6 years, overall survival (63% and 92%, P < 0.001) and cardiac event-free survival (66% and 95%; P < 0.001) were worse among elderly persons than among younger persons. Workload was the only treadmill exercise testing variable associated with all-cause mortality in both age groups, and the strength of association was similar. Workload and angina with exercise testing were associated with cardiac events in both age groups, whereas a positive exercise electrocardiogram was associated with cardiac events only in younger persons (P < 0.05 for all comparisons). After adjustment for clinical variables, workload was the only additional treadmill exercise testing variable that was predictive of death (P < 0.001) and cardiac events (P < 0.05); the strength of the association was similar in both age groups. Each 1-metabolic equivalent increase in exercise capacity was associated with a 14% and 18% reduction in cardiac events among younger and elderly persons, respectively. Conclusions: In elderly persons, treadmill exercise testing provided prognostic information that is incremental to clinical data. After adjustment for clinical factors, workload was the only treadmill exercise testing variable that was strongly associated with outcome, and its prognostic effect was of the same magnitude in elderly and younger persons.