Hospitalized Adult Patients with 2009 Pandemic Influenza A (H1N1) in Kaunas, Lithuania

Auksė Mickienė,Irena Nedzelskienė,Ona Blauzdžiūnienė,Rūta Nadišauskienė,Vidas Pilvinis,Daiva Vėlyvytė,Lina Daniusevičiūtė,Raimundas Sakalauskas,Neringa Vanagaitė,Liucija Jodžiūnienė,Andrius Macas

doi:10.3390/medicina47010002

Abstract

The objective of this study was to identify case characteristics and clinical course of the disease in patients hospitalized with 2009 pandemic influenza A (H1N1) infection during the first wave of the pandemic and to identify risk factors associated with the complicated course of illness. A retrospective study of adult cases of the laboratory-confirmed 2009 pandemic influenza A (H1N1) virus admitted to three hospitals in Kaunas between November 1, 2009, and March 15, 2010, was carried out. The main outcome measures were clinical characteristics, risk factors for complicated disease, treatment, and clinical course of the disease. The study enrolled 121 of the 125 patients hospitalized due to 2009 pandemic influenza A (H1N1) virus infection. The median age was 31 years (range, 18-83); 5% of the patients were aged more than 65 years. Pregnant and postpartum women comprised 26% of all hospitalized cases. Nearly half (49.5%) of those who underwent chest radiography had findings consistent with pneumonia, which was bilateral in one-third of cases. The risk to have pandemic influenza complicated by pneumonia increased significantly with one-day delay from symptom onset to antiviral treatment (OR, 2.241; 95% CI, 1.354-3.710). More than half (57%) of the patients received antiviral treatment. In 45% of the treated patients, antiviral drugs were administered within 48 hours from symptom onset. Intensive care was required in 7.4% of the cases. The overall mortality was 5% (6/121). The median age of the patients who died was 43.5 years (range, 23-62); 4 patients had been previously healthy, 1 patient suffered from chronic lympholeukemia, and 1 patient was a pregnant woman. The 2009 pandemic influenza A (H1N1) caused considerable morbidity in a significant proportion of hospitalized adults. The main risk factor associated with the complicated course of illness was delayed antiviral treatment.

Highlights

The novel influenza A (H1N1) virus was first identified in Mexico in April 2009
Patients admitted to the hospitals mentioned above were considered eligible for inclusion into the study if they had 2009 influenza A (H1N1) virus infection confirmed by the detection of the virus from the nasopharyngeal swab sample by a real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay using test kits supported by the World Health Organization (WHO) from the Centers for Disease Control and Prevention (CDC) (CDC RT-PCR protocol for detection and characterization of swine influenza, version 2009, CDC REF.#I-007-05) [6]
The study involved three settings: the tertiary hospital, the university-associated city hospital with the ward specially designed for the treatment of infectious diseases patients, and the regional hospital

Summary

Introduction

The novel influenza A (H1N1) virus was first identified in Mexico in April 2009. Different from the strains in the past and containing a unique combination of gene segments from swine, avian, and human lineages, this new virus appeared to be able to spread among human beings leading to influenzalike symptoms and progressing in a few cases to viral pneumonia, respiratory failure, and death. In Lithuania, the first case of pandemic influenza was diagnosed on June 26, 2009, in a traveler who had returned from India. Since the beginning of November, a sustained local spread of the pandemic influenza virus within the country was documented. A total of 69 000 influenza cases were registered during the first wave of the pandemic. The laboratory-confirmed pandemic influenza was reported in 810 cases resulting in 23 deaths [2]

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