The eighth edition of our text is the first since the death of John Brocklehurst, whose name it rightly bears, as its originator and longtime editor. In his Guardian obituary (http://www.the guardian.com/science/2013/jul/17/john-brocklehurst), Ray Tallis (himself a former editor of Brocklehurst, in its third to sixth editions) honored John as “the leading geriatrician of his generation,” and a man who “brought scientific gerontology to bear on our understanding of the diseases of old age.” With other early leaders, he organized training programs that helped define the specialty and guide geriatric medicine in its critical adolescent years. Those physicians laid the foundation that allowed geriatric medicine to consist of approaches and procedures that were well enough defined to be tested. This proved fortunate, because medicine was entering the evidence age, which soon demonstrated the merit of the approach. They had a view of geriatric medicine as more than “internal medicine with social work consult.” Even so, understanding just the claim of geriatric medicine continues to evolve. In the seventh edition, and continued here in the eighth, we press ahead with the view of geriatric medicine as the care of frail older adults.¹ Anyone who knows the frailty literature will recognize that this is not entirely a settled claim. Still, several points are inarguable.

First, frailty refers to a state of increased risk compared with others of the same age. This same age comparison is necessary. The risk of adverse health outcomes increases with age, so without this, everyone past their fifth decade, when the increase in risk becomes noticeable, would be seen as frail.

Second, frailty is related to age. This is one point that all frailty measures have in common.² Frailty becomes more common with age; the absolute variability in risk increases, even as relative variability declines after menopause.³ Both trends indicate systems that are moving closer to failure. The first (increase in absolute variability) shows that more people are at an increased risk; the second, a decline in relative variability, captured by a reduction in the coefficient of variation, is compatible with a decline in the response repertoire. Older adults have less to fight back with. In other words, their repair processes are less efficient, which is evidenced, among other things, in prolonged recovery times.⁴

Third, although the use of dichotomous cut points can obscure the extent of agreement, it is clear that the phenotype definition⁴ and the deficit accumulation definition⁵ bear much in common, as do most current operational definitions, because these typically depend on either or both approaches.^2,6–12 Each identifies people who are at increased risk. For example, when people have none of the five phenotype characteristics, they have fewer deficits than when one is present.⁷ Likewise, people with all five phenotypic features present (e.g., weight loss, reduced higher order activities such as gardening and heavy housework, feeling exhausted, reduced grip strength, slower walking speed) have the highest number of deficits overall.⁷ As ever, theses can be nuanced. Given that risk cannot exceed 1, and given that at some age, it becomes indistinguishable from 1, there must be an age at which everyone is frail. These details, like so much else, require elaboration. In consequence, there is no merit in abandoning the value of understanding frailty, even if there is disagreement about its precise operational definition.

The reason that frailty is so central to geriatric medicine is compelling. The challenge of aging to medical care lies in the complexity of frailty. As people age, it is not just that any given illness becomes more common—all illnesses become more common. Age-related change, whether it crosses a disease threshold or not, follows, on average, a trajectory of decline. Managing single illnesses is tricky enough, but the complexity imposed by frailty—managing illness in the presence of multiple interacting medical and social problems that each become more common with age—requires a specialized body of knowledge and skills. This is what constitutes geriatric medicine.

With this focus on frailty in mind, we have continued to revise and evolve the textbook. The current eighth edition includes new entries on gerontechnology, homelessness, emergency and prehospital care, HIV and aging, intensive treatment of older adult patients, telemedicine, and the built environment. We have also added a chapter on frailty, written by two authors with much experience in regard to the various ways to define frailty. Obtaining a nonpartisan view is important because all chapter authors have been encouraged to revise their chapters, not just in relation to developments in their area, but also to ensure a discussion on how it is affected by frailty. For our part, we have aimed to advocate for both types of changes, which often have resulted in mutually beneficial exchanges. This reflects how the field is evolving. It also is a pragmatic challenge for textbooks in the Internet era. The goal is less to be a compendium of all the latest information than to be an account of what is usefully known. We see the role of this text as providing context and some sense of the evolution of an area. This approach can provide value in ways that merely recitation of what is up to date at the moment might not always achieve. This has long been a goal of Brocklehurst, and one that we are keen to continue.

In the eighth edition, we recognize the stellar contributions of Professor Kenneth Woodhouse, who joined us in the seventh edition, as we began the more explicit shift in emphasis toward frailty. Now we are delighted to welcome Professor John Young. He has conducted much of the useful UK research on clinical geriatric medicine for the last decade, securing our discipline a solid evidence base, and pointing out where we need to build further. This direction has benefitted enormously from his long history of clinical practice in geriatric medicine. Those skill sets are now brought to bear in the National Health Service for England and Wales, for which he is now the Clinical Service Director for Older Adults (or the “frailty czar,” as this post otherwise is known). We feel privileged to have him join us.

As editors and chapter authors, we benefit from the engagement of the many readers who have taken time to let us know what they think of the text, both how it serves and how it might be improved. We thank them for this effort and hope that the dialogue remains ongoing. Providing health care for anyone is a special privilege; providing it for people in great need, even more so. It is not widely recognized enough that the care of frail older adults is a special challenge, requiring particular expertise. When it is done well, geriatric medicine is a thing of beauty, deeply rewarding to patient and practitioner. We wish our reader this joy of geriatrics.