Elderly patients have slightly lower body temperatures than younger adults, and as a result it has been suggested that "fever" be defined as anything > 99 degrees F. One study found that by lowering the definition to this number improved the sensitivity and specificity to 83% and 89%, respectively.
from Hals G. Common diagnoses become difficult diagnoses when geriatric patients visit the emergency department, part I. Emergency Medicine Reports 2010;31(9):101-110.
study referred to: Castle SC, et al. Fever response in elderly nursing home residents: are the older truly colder? J Am Geriatric Soc 1991;39:853-857.
