One of the most important developments of the twentieth century has been the enormous rise in worldwide population in general, and especially the survival of an estimatedsix hundredmillion people agedsixty or older (Ikels, 1991). The increase in the percentage of elderly in the total population results from medical, economic, and social factors plus a decline in the birthrate. According to 1989 U.S. Bureau of the Census figures, persons over sixty-five represented 12 percent of the U.S. population, and it is projected that this proportion will almost double by the year 2030—since the baby-boom generation, born after 1945, will start reaching 65 in 2010.

This fastest-growing segment—the elderly—uses pharmacological and health services more often than any other part of the population (Brock, Guralnik, & Brody, 1990). Aging people are more susceptible to infectious disease. Many suffer from multiple chronic diseases and often from conditions that have grown...