Fever or not fever – that’s the question: A cohort study of simultaneously measured rectal and ear temperatures in febrile patients with suspected infection

Objective: To study how ear and rectal body temperatures relate to each other over time in febrile patients. Methods: Descriptive cohort study with repeated measurements. The setting was a Unit for Infectious Diseases at a county hospital in Sweden. Patients, ≥ 18 years, admitted for suspected infection and with a rectal or ear temperature of ≥ 37.5◦C were invited. 16 females and 24 men, 19 to 94 years were included. Ear and rectal temperature was measured simultaneously every two hours for one day. Results: Mean rectal temperature was higher, compared to both ear sites. Ninety-five percent of the differences between the rectal and ear sites were within 0.6◦C to 1.1◦C. Changes in rectal temperature were smaller and slower than in ear temperature, especially when patients were given temperature-lowering drugs. Conclusions: Adjustments from one temperature site to another is a risk of diagnostic error affecting clinical decision-making. Ear temperature reacts faster than the rectal site to body temperature changes and antipyretics, and is therefore more reliable in the assessment of the patient’s condition. Traditional paradigm for temperature measurement and assessment needs to be replaced with evidence-based science to improve patient safety.