ASSESSMENT OF RISK IN THE ELDERLY
The decision to operate should not be based on age alone but should
reflect an assessment of the risk-benefit ratio of individual cases (see Chapter
24
). Increased life expectancy, safer anesthesia, and less invasive surgical
techniques have made it possible for a greater number of geriatric patients to be
considered for surgical intervention. Surgical risk and outcome in patients 65 years
and older depend primarily on four factors: (1) age, (2) the patient's physiologic
status and coexisting disease (American Society of Anesthesiologists [ASA] class),
(3) whether the surgery is elective or urgent, and (4) the type of procedure.
Earlier studies suggest that anesthetic complications are related
to age.[52]
Surgical mortality also increases with
age.[53]
[54]
[55]
In addition, age is an independent predictor of any serious adverse perioperative
event.[56]
[57]
These data emphasize that extremes of age do incur additional risk. For instance,
perioperative mortality in nonagenarians ranges from 0% to 20%, depending on the
type of procedure.[3]
[58]
After hip fracture repair, patients 90 years and older are more likely to die during
hospitalization than younger patients are.[59]
However, age alone should not necessarily be a deterrent from surgery. Prospective
survival studies in surgical patients older than 75 years demonstrate that after
an initial high mortality rate, survival in this group as a whole approaches that
of an age-matched population.[60]
When surgical
morbidity and mortality rates for nonagenarians are compared with age-, sex-, and
calendar year-matched peers from the general population, there is a decrease in patient
survival at 1 year that reverses by 2 years, with observed survival at 5 years comparable
to the rate expected.[61]
In surgical patients
100 years and older, the reported 48-hour, 30-day, and 1-year mortality rates are
0%, 16.1%, and 35.5%, respectively. When compared with survival rates for age-,
gender-, and calendar year of birth-matched peers from the general population, the
survival rate for centenarians who undergo surgery and anesthesia is comparable to
the rate expected for nonsurgical patients.[62]
Although age has been shown to be a predictor of poor operative
risk, the effect of age cannot be separated from ASA status or underlying comorbidity.
[56]
For instance, in carotid endarterectomy, mortality
is greater in patients older than 80 years. However, illness severity has a greater
impact on mortality after extracranial vascular surgery than octogenarian status
per se does.[63]
Thus, it is hard to pinpoint how
aging alters surgical risk. It is likely that the association between age and surgical
risk is related to the aging process and its ongoing decrease in functional organ
reserve.
Emergency surgery is an independent predictor of adverse postoperative
outcomes in older surgical patients undergoing noncardiac surgery.[61]
[64]
Poorer preoperative physiology and preparation
have a large influence on these results. Emergency care presents special problems,
such as atypical manifestations, alterations in the pulmonary and circulatory systems,
and fluid and electrolyte balance changes secondary to modifications in metabolic
needs and body composition with aging—all of which complicate resuscitation.
Surgical mortality in the elderly varies widely according to the
procedure.[54]
[55]
[61]
The fact that risk varies widely with the
type
of surgery is well recognized. The current guidelines for cardiovascular evaluation
of patients undergoing noncardiac surgery provide a useful means of categorizing
procedures into those with low, intermediate, and high risk.[47]
