Long fever Fever as a long-term risk factor for mortality in persons in assisted living facilities

The aging population and increasing use of assisted living facilities necessitate a better understanding of risk factors for adverse outcomes. Fever as a long-term risk factor in elderly populations remains understudied.

We analyzed data from 16,523 veterans in assisted living facilities between 2012-2022, examining the relationship between fever (defined as temperature ≥100.4°F) and mortality at 90-, 365-, and 730-days post-admission. Subjects were categorized by fever timing (none, at intake, or after intake), temperature severity, and percentage of days febrile.

Fever at intake and fever after admission were associated with significantly increased mortality compared to no fever (p < .001) at all time points. Higher fever temperatures (>105°F) and a greater percentage of days febrile (>5 %) correlated with worse mortality. Patients with fever at intake and a few percentage of days febrile (<5 %) had an OR of 1.24 (95 % CI 1.01-1.53) for mortality by 1 year compared to patients who did not have a fever. High (>105°F) early fever had an OR of 1.46 (95 % CI 1.20-1.78), and early fever with many days febrile (>5 %) had an OR of 1.53 (95 % CI 1.33-1.75) for mortality at 730 days compared to patients with no fever.

Fever in assisted living residents increases mortality risk for up to two years, depending on temperature severity and duration. These findings suggest a "long fever" phenomenon, where acute febrile episodes may have lasting consequences. Incorporating fever status into risk stratification may help identify high-risk patients requiring enhanced monitoring and care.