The relationship between age and fever magnitude

Background. Infections are an important cause of morbidity and mortality in older people; however, they are often difficult to diagnose because the si gns and symptoms of infection in older people are frequently atypical. Feve r, one of the most important signs of infection, is a case in point. Prelim inary evidence suggests that the febrile response in older persons is blunt ed, leading to the clinical maxim, "the older, the colder." The objective o f this study was to assess the effect of age on the febrile response to mod erate-to-severe pneumonia in hospitalized patients adjusted for the effect of anatomic site at which the temperature was measured. Methods: This is a retrospective cohort study of 320 hospitalized patients with moderate-to-se vere pneumonia. The study was designed to assess the effect of age on the f ebrile response to moderate-to-severe pneumonia in hospitalized patients, a djusting for the effect of the anatomic location of the temperature measure ment. The highest temperature of each day and the anatomic sites at which t emperatures were taken (axillary, oral, rectal, or other) on days I and 2 o f infection and at hospital discharge. Baseline demographic information, in cluding age, were obtained for each patient. Results: There were 320 patien ts (median age, 64 years; range, 18-97 years). Using a linear regression mo del, significant inverse correlations were found between age and the temper ature for patients on the first and second days of hospitalization (P < 0.0 01). For each decade increase in age, the average temperature on the first 3 days of infection was lower by 0.15 degreesC. Temperature at discharge, a surrogate for baseline temperature, also decreased at an equal rate with a ge. Conclusion: In this study, the febrile response to infections was reduc ed with increasing age and baseline temperatures were generally lower in ol der patients.