Influenza With and Without Fever: Clinical Predictors and Impact on Outcomes in Patients Requiring Hospitalization

Abstract

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>The Infectious Diseases Society of America influenza guidelines no longer require fever as part of their influenza case definition in patients requiring hospitalisation. However, the impact of fever or lack of fever on clinical decision-making and patient outcomes has not been studied.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>We conducted a retrospective review of adult patients admitted to our tertiary health service between April 2016 and June 2019 with laboratory-confirmed influenza, with and without fever (≥37.8ºC). Patient demographics, presenting features and outcomes were analysed using Pearson’s Chi-Squared test, Wilcoxon rank-sum test, and logistic regression.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Of 578 influenza inpatients, 219 (37.9%) had no fever at presentation.</jats:p> <jats:p>Fever was less likely in individuals with a non-respiratory syndrome (adjusted odds ratio [aOR]: 0.44, 95% CI [0.26 - 0.77]), symptoms for ≥ 3 days (aOR 0.53, 95%CI [0.36 - 0.78]), influenza B infection (aOR: 0.45, 95% CI [0.29 - 0.70]), chronic lung disease (aOR: 0.55, 95% CI [0.37 - 0.81]), age ≥ 65 (aOR: 0.36, 95%CI [0.23 - 0.54]) and female sex (aOR 0.69, 95% CI [0.48,0.99]).</jats:p> <jats:p>Patients without fever had lower rates of testing for influenza in the ED (64.8% vs 77.2%, p= 0.002) and longer inpatient stays (median 2.4 vs 1.9 days, p=0.015). These patients were less likely to receive antiviral treatment (55.7% vs 65.6%, p=0.024) and more likely die in hospital (3.2% vs 0.6%, p=0.031) and these differences persisted after adjustment for potential confounders.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Absence of fever in influenza is associated with delayed diagnosis, longer length of stay and higher mortality.</jats:p> </jats:sec>

Hospitalisation, morbidity and outcomes associated with respiratory syncytial virus compared with influenza in adults of all ages

“…To our knowledge, there is only very limited data exploring this comparison, 9 and our paper is one of the first to link key presenting phenotypes with diagnostic patterns and timing of PCR testing. 10 We found that those presenting with influenza were far more likely to be febrile, whereas only a minority of RSV patients were febrile. The RSV group was significantly more likely to be tachypnoeic and less likely to be shocked as indicated by systolic hypotension.…”

“…An important pattern demonstrated in this paper was the key comparative differences in clinical phenotype between influenza and RSV. To our knowledge, there is only very limited data exploring this comparison, 9 and our paper is one of the first to link key presenting phenotypes with diagnostic patterns and timing of PCR testing 10 . We found that those presenting with influenza were far more likely to be febrile, whereas only a minority of RSV patients were febrile.…”

Screening for COVID-19 in Older Adults: Pulse Oximeter vs. Temperature

“…One study found older adults (N = 1,318), presented to the emergency department with influenza 2-5 days after symptom onset (14). In other studies, seeking treatment occurred up to 1 week after symptom onset (15,16). This delay in seeking health care increases their mortality risk (14).…”

“…This delay in seeking health care increases their mortality risk (14). Therefore, the objective measure of a temperature and the threshold of 100.4 F as a fever indicator does not provide a sufficient indicator of infection in older adults and may delay the diagnosis and treatment for COVID-19 (15,16).…”

SAPS 2 score valid parameter for outcome in severe influenza

“…The largest number of studies has evaluated isolated risk factors leading to lethal outcome and only a few of them have been focused on the complete palette of predictors for development of a severe form of the disease and lethal outcome [9][10][11][12][13][14][15][16]. From the clinical practice point of view, the awareness/recognition of the risk factors and predictors for lethal outcome of influenza is of particular importance in bringing timely and exact decision for hospitalization, treatment or undertaking special measures for intensive monitoring of these patients.…”