Prevalence of microbiologically-confirmed influenza in patients with influenza-like illness in primary care and clinical and epidemiological characteristics
Moragas A., Garcia-Sangenís A., Escudero AP., Faro CB., Ibáñez RH., Brotons C., Vilella T., Puig M., Casaponsa RF., Guerrero SC., Pera H., van der Velden AW., Butler CC., Llor C.
Objectives. We evaluated the prevalence of microbiologi-cally-confirmed influenza infection among patients with influ-enza-like symptoms and compared the clinical and epidemio-logical characteristics of patients with and without influenza infection. Methods. Retrospective study of a cohort of patients with influenza-like symptoms from 2016 to 2018 who partic-ipated in a clinical trial in thirteen urban primary centres in Catalonia. Different epidemiological data were collected. Patients rated the different symptoms and signs on a Likert scale (absent, little problem, moderate problem and severe problem) and self-reported the measure of health status with the Euro-Qol visual analogue scale. A nasopharyngeal swab was taken for microbiological isolation of influenza and other microor-ganisms. Results. A total of 427 patients were included. Micro-biologically confirmed influenza was found in 240 patients (56.2%). The percentage of patients with moderate-to-severe cough, muscle aches, tiredness and dizziness was greater among patients with microbiologically confirmed influenza. The self-reported health status was significantly lower among patients with true flu infection (mean of 36.3 ± 18.2 vs 41.7 ± 17.8 in patients without influenza; p<0.001). Conclusion. Clinical findings are not particularly useful for confirming or excluding the diagnosis of influenza when intensity is not considered. However, the presence of moder-ate-to-severe cough, myalgias, tiredness and dizziness along with a poor health status is more common in patients with confirmed flu infection.