Biological age--a concept whose time has come: a preliminary study.
OBJECTIVE: Chronology poorly predicts biological age (BA) or physiologic reserve (PR). An objective approach to the heterogeneity of aging would greatly help clinical decision making in the elderly. MATERIALS AND METHODS: The first pilot study evaluated 130 "healthy" volunteers, ages 70 to 95 years. A summary BA/PR index was developed, using measures of endurance, strength, flexibility, balance, cognition, depression, comorbidity, and exercise. The second study applied the BA/PR concept to prediction of death after a first elective coronary artery bypass graft, using a Veterans Administration database. RESULTS: The BA/PR index was a better predictor of 3-year functional outcomes and death than was chronological age. In the coronary artery bypass graft study, the inclusion of BA/PR variables significantly improved prediction of 6-month and long-term death for Veterans Administration patients. CONCLUSIONS: The usefulness of a biological age (BA/PR) approach in predicting outcomes in the elderly was supported. Needed research should develop tools for routine "tracking" of the aging process.