1022. The Role of Baseline Body Temperature in Neutropenic Fever

Abstract

Background The management of neutropenic fever patients is challenging – from identification to diagnosis to treatment. We hypothesize that patients’ individual baseline body temperature provides diagnostic and prognostic value. Methods This is an analysis of 92 adult patients admitted for neutropenic fever to a tertiary medical center over 1 year period. We modelled the length of stay and the ability to find a definitive diagnosis using the change in body temperature from each patient’s outpatient baseline, the neutropenia level and overall patient acuity on admission, persistence of fever over 48-72 hours, and age. All temperatures were standardized to oral. Refer to Table 1 for the inclusion and exclusion criteria and statistical methods. Table 1.Inclusion and exclusion criteria and statistical methods. Results Refer to Tables 2 and 3 for demographics and descriptive statistics of temperature readings, to Table 4 for advanced statistical analyses. Importantly, the average baseline body temperature was at 36.7C; the average fever on admission was at 38.1C; based on the ≥ 38C cutoff, only 24% of patients had persistent fever over 48-72 hours but based on personalized cutoffs at > 2 standard deviations (SDs) or > 3 SDs above their outpatient baseline, 54% and 34% had persistent fever, respectively; the etiology of fever was identified in 48% of patients, all of which constituted infections; our multiple regression model demonstrated that a longer length of stay (LOS) of ≥ 4 days was predicted by larger deviation from baseline body temperature at admission and independently by fever persistence, after correcting for age, neutropenia level, and need for ICU level of care on admission. A similar model could not predict the ability to identify a fever-explaining diagnosis. Conclusion Given the average outpatient baseline body temperature of 36.7 +/- 0.3C, at 2 standard deviations (SDs) above this baseline, only 3% of patients would be at the 38C cutoff for fever, at 3 SDs, it would be 20%, thus rendering the standard 38C cutoff too high to be useful in identifying many neutropenic fever cases and supporting the use of personalized cutoffs based on patient’s baseline temperature. Further, consideration of the specific deviation from patients’ baseline body temperature could serve as a predictor for hospital LOS in patients admitted with neutropenic fever. Disclosures All Authors: No reported disclosures.

Human Body Temperature Circadian Rhythm in Health and Disease

“…Certainly, medical illnesses such as infections, malignancies, thyroid disorders, among many others, can strongly affect our temperature as well. Interestingly, the 37°C normothermia average standard had been challenged by several research groups including Obermeyer et al [11], Diamond et al [12] and Corsi et al [13], where a lower non-core average body temperature of 36.6°C, 36.1°C and 36.71°C were reported, respectively. While these findings were based on diverse cohorts and constituted only a point-in-time observation, Protsiv et al [14] carried out a longitudinal study, where the measurements were adjusted for age, weight, height, and for some data sets for time of the day as well.…”

“…This is illustrated by measured intrapersonal standard deviation of 0.32°C [12] and 0.39°C to 0.4°C [15] in healthy adults, while the range of measured interpersonal body temperatures in the same research studies spanned 2-3°C. This realization prompted several researchers to propose that "one size does not fit all" as it comes to normal body temperature [12,13]. The definition of normothermia is further complicated by the fact that even within the same organism body temperature changes in a cyclic manner with a period of approximately 24 hours -the circadian rhythm of body temperature, which is the focus of the next chapter section.…”