Clinical differences between H3N2 and H1N1 influenza 2012 and lower respiratory tract infection found using a statistical classification approach

Abstract

Dimitris Petridis,1 Paul Zarogoulidis,2,3 Anastasios Kallianos,4 Ioannis Kioumis,2 Georgia Trakada,5 Dionysios Spyratos,2 Antonis Papaiwannou,2 Konstantinos Porpodis,2 Haidong Huang,6 Aggeliki Rapti,4 Wolfgang Hohenforst-Schmidt,7 Konstantinos Zarogoulidis2 1Department of Food Technology, Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, Greece; 2Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece; 3Department of Interventional Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital, University Duisburg-Essen, Essen, Germany; 42nd Pulmonary Department, "Sotiria" Hospital for Chest Diseases, Athens, Greece; 5Department of Clinical Therapeutics, Division of Pneumonology, Medical School, National University of Athens, Athens, Greece; 6Department of Respiratory Diseases, Changhai Hospital/First Affiliated Hospital of the Second Military Medical University, Shanghai, People's Republic of China; 7II Medical Department, "Coburg" Regional Clinic, University of Wüerzburg, Coburg, Germany Background: Influenza A H1N1 and H3N2 are two influenza waves that have been identified in past years. Methods: Data from 77 inpatients from three tertiary hospitals were included and statistical analysis was performed in three different clusters. Results: Thirty-four patients (44.2%) had respiratory distress upon admission, 31.2% had a smoking history or were active smokers, 37.7% manifested disease symptoms, and 7.8% were obese (body mass index >41). The mean age of patients was 51.1 years. Cough was the most common symptom observed in 77.9% of the patients, accompanied by sputum production (51.9%) and fatigue (42.9%). Hemoptysis and vomiting were rarely recorded in the patients (9.1% and 16.9%, respectively). Oseltamivir administration varied between 0 and 10 days, giving a mean value of 2.2 days. In particular, 19 patients received no drug, 31 patients received drug for only for 1 day, 19 patients for 5 days, and 8 patients from 2 to 10 days. Conclusion: Clusters of symptoms can be used to identify different types of influenza and disease severity. Patients with vaccination had pneumonia, whereas patients without vaccination had influenza A. Patients more than 54.5 years old had H3N2 and patients less than 54.5 years had H1N1. White blood cell count values increased from normal to elevated in H3N2 patients but still remained abnormal in lower tract infection and H1N1 patients. Keywords: H3N2, H1N1, influenza outbreak, respiratory infection, vaccination