Predictors of influenza among older adults in the emergency department

Abstract

BackgroundDiagnosis of influenza in older adults may be complicated by atypical presentations or when patients present with complications of an underlying illness. We aimed to identify clinical characteristics and epidemiological factors associated with influenza among community-dwelling adults aged ≥60 years presenting to emergency departments.MethodsWe identified patients with influenza-compatible chief complaints presenting to emergency departments of six acute care hospitals in Ontario, Canada during the 2011/12 and 2012/13 influenza seasons. Clinical characteristics, medical history and demographics were collected by patient interview, chart review and by contacting vaccine providers. Nasopharyngeal swabs were tested for influenza using polymerase chain reaction. We modeled predictors of influenza using multivariable logistic regression models that compared individuals with and without influenza.ResultsOf 1318 participants, 151 (11 %) had influenza (98 A/H3N2, 12 A/H1N1, 4 A [not sub-typed], 37 B). In the multivariable model, clinical symptoms associated with influenza were cough (OR 6.4, 95 % CI 3.2, 13.0), feverishness and/or triage temperature ≥37.2 °C (OR 3.0, 95 % CI 2.0, 4.7), 2–5 days from symptom onset to the emergency department visit (OR 2.2, 95 % CI 1.5, 3.2), and wheezing (OR 2.1, 95 % CI 1.3, 3.3). The effect of cough on influenza increased with older age. Epidemiological factors associated with increased odds for influenza included weeks when ≥10 % influenza tests from provincial laboratories were positive (OR 5.1, 95 % CI 1.2, 21.7) and exposure to a person with influenza-like illness (OR 1.9, 95 % CI 1.3, 2.8). Among participants with influenza, only 47 (31 %) met the U.S. Centers for Disease Control and Prevention criteria for influenza-like illness (temperature ≥37.8 °C and cough and/or sore throat).ConclusionsAs in younger adults, cough and feverishness are the two symptoms most predictive of influenza in the elderly. Current influenza-like illness definitions did not adequately capture influenza in older adults.

Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility — King County, Washington, March 2020

“…Approximately half of all residents with positive test results did not have any symptoms at the time of testing, suggesting that transmission from asymptomatic and presymptomatic residents, who were not recognized as having SARS-CoV-2 infection and therefore not isolated, might have contributed to further spread. Similarly, studies have shown that influenza in the elderly, including those living in SNFs, often manifests as few or atypical symptoms, delaying diagnosis and contributing to transmission (6)(7)(8). These findings have important implications for infection control.…”

The effects of age on clinical characteristics, hospitalization and mortality of patients with influenza‐related illness at a tertiary care centre in Malaysia

“…23 Another study also found that lowering the triage temperature to 37.2°C increased the specificity of predicting influenza from 75% to 79%. 9 The composite variable of self-reported fever and a temperature of ≥37.2°C…”

“…1,8 Nevertheless, fever, cough and acute illness onset remain predictive of influenza among older adults. 8,9 Malaysia is a middle-income country in South-East Asia with a population of 31 million and a gross national income (GNI) per capita of USD 9800 as of 2017. 10 Disability rates in older Malaysians are significantly higher at 16% compared to developed countries such as Canada which only reported a 6% disability rate when the same assessment tool for activities of daily living was employed.…”

Using a novel rapid viral test to improve triage of emergency department patients with acute respiratory illness during flu season

“…Rapid identification of respiratory viruses is crucial for prevention of nosocomial transmission especially given the immune compromised and inherently vulnerable nature of ED patients, including very young and elderly patients, and those with chronic health conditions. Despite numerous attempts, syndromic formulas for distinguishing influenza from other respiratory illnesses lack the sensitivity required to inform clinical decisions regarding patient care and isolation [14][15][16][17]. The gold standard for viral testing is laboratory polymerase chain reaction (PCR).…”