Methods
Sample
Data were obtained from the Longitudinal Study of Aging (LSOA).23 The LSOA is a prospective
survey of 5151 community-dwelling persons aged 70 years and older who were initially interviewed in the 1984 National Health Interview Survey, Supplement on Aging.24·25 Participants
were reinterviewed in 1986, 1988, and 1990. The LSOA includes information on disability, health
status, health care utilization, and mortality for a probability sample of the national
population. All analyses, except where otherwise noted, are based on the weighted sample to reflect
this population. A complete description of the LSOA is given elsewhere.26