Three terms are commonly used interchangeably to identify vulnerable older
adults: comorbidity, or multiple chronic conditions, frailty, and disability.
However, in geriatric medicine, there is a growing consensus that these are
distinct clinical entities that are causally related. Each, individually, occurs
frequently and has high import clinically. This article provides a narrative
review of current understanding of the definitions and distinguishing
characteristics of each of these conditions, including their clinical relevance
and distinct prevention and therapeutic issues, and how they are related. Review
of the current state of published knowledge is supplemented by targeted analyses
in selected areas where no current published data exists. Overall, the goal of
this article is to provide a basis for distinguishing between these three
important clinical conditions in older adults and showing how use of separate,
distinct definitions of each can improve our understanding of the problems
affecting older patients and lead to development of improved strategies for
diagnosis, care, research, and medical education in this area