David O. Warner, M.D.
Professor of Anesthesiology
Mark A. Warner, M.D.
Professor of Anesthesiology
Mayo Clinic and Foundation,
Rochester, MN 55905
warner.david@mayo.edu

With the aging of the United Statesā population and the progressive lengthening of life expectancy, the number of elderly patients requiring anesthesia and surgery will continue to grow. Thus, perioperative risk in the elderly is an increasingly important issue.

Many studies have documented that the frequency of perioperative complications increases with age. For example, a large prospective survey performed in France from 1978 to 1982 documented an approximately 10-fold increase in the rate of complications specifically attributed to anesthesia as the age of patients increased from 30 to 80 years old.¹ This finding is not surprising given that the prevalence of significant co-morbid conditions such as cardiovascular disease is increased in the elderly². However, it is unclear whether the increased frequency of complications can be attributed to these co-morbid conditions or whether advanced age itself is an independent risk factor. In other words, is the healthy elderly patient at increased risk? The answer to this question may depend upon the specific disease process and complication addressed, and it is probably unwise to make generalizations.

As an example of the difficulties encountered in assessing age itself as an independent risk factor, many studies examine risk factors for perioperative cardiovascular events in both cardiac operations and noncardiac surgery. Although several studies find that age is an independent predictor of risk, many do not.³ Interpretation of these studies is complicated by heterogeneous definitions of disease and outcomes, differing modes of clinical care and diversity in the type of surgical procedures examined. Furthermore, subclinical preoperative cardiovascular disease, which is more prevalent in the elderly, may be difficult to detect. This subclinical disease may increase risk, yet it will not be included as a factor in analysis of risk.

Although the overall frequency of perioperative complications is increased in the elderly, it is still relatively low. For example, in the above-mentioned French survey, the frequency of complications related to anesthesia was 0.5 percent in patients greater that 80 years old.¹ In a case series of 795 patients 90 years of age and older undergoing surgery at Mayo Clinic, 9.4 percent experienced serious morbidity within 48 hours after surgery, with the mortality rate being 1.6 percent.⁴ In a similar study, of 31 patients aged 100 to 107 years undergoing surgical procedures, only one major complication within 48 hours was observed, and the long-term survival rate was comparable to the expected rate for this population⁵. These findings suggest that appropriate surgery should not be denied simply on the basis of age.

Most studies of perioperative risk concentrate on physiologic measures such as presence and occurrence of specific pathologic states as predictors of risk and as outcome variables. However, the functional status of the elderly may also be an important predictor of risk. Functional status is defined as behaviors necessary to maintain daily life (e.g., activities of daily living), and includes aspects of social and cognitive functioning. Several studies have now shown that these functional measures may be even more important than standard burden-of-illness indices (such as acute physiologic scores) in predicting mortality in hospitalized patients.⁶ These measures have not yet been applied specifically to studies of perioperative outcome. Indeed, from the standpoint of the patient, the most important perioperative outcome measure may be a change in functional status, rather than the occurrence of an acute physiologic complication that may or may not affect the ultimate quality of life. More subtle effects of anesthesia and surgery, such as the prolonged cognitive decline recently noted after surgery in some elderly patients, may be better appreciated utilizing this approach. ⁷

References

1. Tiret L, Desmonts JM, Hatton F, Vourcāh G. Complications associated with anaesthesia ö a prospective survey in France. Can Anesth Soc J. 1986;33;336-344.
A large survey of the oucomes of approximately 200,000 anesthetics in France from 1978-82 that examined several risk factors for complications.
2. Arvidsson S, Ouchterlony J, Nilsson S, et al. The Gothenburg study of perioperative risk. I. Preoperative findings, postoperative complications. Acta Anaesthesiol Scand. 1994; 38:679-690.
A prospective evaluation of a general surgical population, documenting the prevalence of pre-operative co-morbid conditions as a function of age.
3. Mangano DT. Perioperative cardiac morbidity. Anesthesiology. 1990; 72:153-184.
Now several years old, but still an excellent review of the contribution of age and other factors to cardiac risk.
4. Hosking MP, Warner MA, Lobdell CM, et al. Outcomes of surgery in patients 90 years of age and older. JAMA. 1989; 261(13):1909-1915.
A large case series documenting generally good outcomes in this patient population.
5. Warner MA, Saletel RA, Schroeder DR, et al. Outcomes of anesthesia and surgery in people 100 years of age and older. J Am Geriatr Soc. 1998; 46(8):988-993.
A smaller case series documenting generally good outcomes in this patient population.
6. Inouye SK, Peduzzi PN, Robison JT, et al. Importance of functional measures in predicting mortality among older hospitalized patients. JAMA. 1998; 279(15):1187-1193.
A good introduction to the topic of functional status and its importance as a prognostic factor in the elderly.
7. Moller JT, Cluitmans P, Rasmussen L, et al. Long-term postoperative cognitive dysfunction in the elderly ISPOCD1 study. ISPOCD investigators. International Study of Post-Operative Cognitive Dysfunction. Lancet. 1998; 351:857-861.
Documented by careful neuropsychiatric evaluation that there is a significant, long-term (at least 3 months) cognitive dysfunction associated with anesthesia and surgery in approximately 10% of elderly patients.