Adults with Neither Fever Nor Cough Are Unlikely to Have Influenza

But, only about 10% of patients with respiratory illness lacked both symptoms in this small Canadian study.


In a retrospective case-control study of adult patients who presented to two emergency departments in Toronto from April to June 2009 with fever or respiratory symptoms, investigators compared clinical findings between 117 patients with confirmed H1N1 influenza (cases) and 236 patients without influenza (controls). Influenza was confirmed by reverse transcriptase-polymerase chain reaction testing of nasopharyngeal swabs, which were obtained from all patients.

Significantly fewer cases than controls had chronic underlying diseases (44% vs. 55%). Cases were significantly more likely than controls to have cough (odds ratio, 7.8), fever (OR, 3.0), tachycardia (OR, 2.3), headache (OR, 2.0), and myalgia (OR, 1.9) and were significantly less likely to have normal oxygen saturation (OR, 0.5). Patients with presence of cough and fever had an OR for influenza of 5.3. In multivariate analysis, only fever, cough, and younger age were associated with influenza. Cough was less predictive of influenza in patients ?65 (OR, 1.7) than in younger patients (OR, 13 for patients aged 18–44). Absence of both fever and cough had a negative predictive value for influenza of 99%; however, only 8% of controls had neither finding.


Citation(s):

Lee TC et al. Predictors of pandemic influenza infection in adults presenting to two urban emergency departments, Toronto, 2009. CJEM 2011 Jan; 13:7.