Chapter 32: Geriatric Principles

PREVALENCE, LETHALITY, AND UNDERRECOGNITION OF TOXIC EXPOSURE

The population is aging steadily across the world. In the United States, people older than 65 years of age comprise an increasing proportion of the population at large (14.5%), and those 85 years and older represent the fastest growing segment of the population.³ The elderly also comprise an increasing proportion of patients cared for in multiple medical settings, not the least of which is the emergency department (ED) setting. As a result of continuing advances in health education, technology, and pharmacotherapy, many people are living longer. Long life is associated with an increased disease burden. The aging of the “baby boomer” generation (people born between 1946 and 1964) is rapidly changing the medical landscape. Compared with all other age groups, patients 65 years of age and older account for 16% of the total population of patients who visit an ED, one-third of ED ambulance arrivals, and the highest proportion of patients in EDs triaged as emergent.³² Moreover, this population represents the highest number of hospital and intensive care unit admissions.¹⁵⁹

Although the elderly account for only a small minority of toxicologic exposures, when exposed, they have a high overall mortality rate. Among exposures reported to the American Association of Poison Control Centers (AAPCC), the fatality ratio for adults (ie, number of cases divided by number of deaths) exhibits a bimodal pattern, declining after age 30 until age 60, when it again rises (Chap. 130).

The factors associated with the increased fatality ratio after age 60 are complex, but are likely due in part to physiologic vulnerability. The geriatric population is physiologically heterogeneous, encumbering research that seeks to differentiate “normal” senescence from changes that occur as a result of disease. This heterogeneity is pertinent to clinical response to xenobiotics, variability of pharmacokinetics, and recovery from exogenous insults, such as adverse drug effects and toxicologic emergencies.

Exposures reported to the AAPCC underestimate the serious consequences for elderly people exposed to xenobiotics that are toxic or potentially toxic. Data from the National Electronic Injury Surveillance System–Cooperative Adverse Drug Event Surveillance Project (NEISS-CADES) indicate that patients aged 65 years and older accounted for 25% of estimated visits related to adverse drug events (ADEs), with almost 50% of such visits requiring hospitalization or prolonged monitoring in the ED during 2004–2005.²⁰ Furthermore, the incidence of ADEs increases steeply from age 65 years through the tenth decade of life.²⁰ More recent NEISS-CADES data indicate that almost 50% of elders who required emergency hospitalization as a result of ADEs are 80 years of age or older.¹⁹ Finally, the problem is likely even greater than the NEISS-CADES study suggests, because their data did not capture ADEs in patients treated or dying outside of EDs, ADEs that could only have been recognized after admission, or that were erroneously diagnosed as non–drug-related problems. A better understanding of the specific ...