Fever in hospitalized medical patients: characteristics and significance.

The occurrence of fever and the clinical profile of febrile patients on the medical service of a teaching hospital were studied prospectively. Thirty-six per cent of 972 patients developed fever (temperature exceeding 38 degrees C). Their 13% mortality rate and 13.2-day average hospital stay exceeded the 3% mortality and seven-day hospitalization for afebrile patients (p less than 0.0001 for both). Most fever episodes occurred during the first two hospital days. Approximately 30% of first and subsequent fever episodes were caused by bacterial infections; illnesses involving tissue necrosis (e.g., stroke, myocardial infarction) accounted for 20%. Five conditions comprised 53% of diagnoses: respiratory and urinary tract infections, neoplasm, myocardial infarction, and drug reaction. Only one patient had a fever of uncertain origin. Several clinical clues used frequently to identify bacterial infections were reevaluated. Patients with bacterial infections had higher temperatures on the first febrile day (mean 38.9 degrees C) and were more likely to have had prior infections than those with other causes of fever (mean 38.3 degrees C, p less than 0.001). Older patients (greater than 75 years) had a lower febrile response to bacterial infections than younger patients. Fever in hospitalized medical patients is a common and important concomitant of increased mortality and length of hospitalization.