Complications and factors associated with severity of influenza in hospitalized children and adults during the pandemic wave of A(H1N1)pdm2009 infections--the Fluco French cohort

Abstract

Background: The emergence of novel A(H1N1)pdm2009 virus threatened to lead to frequent severe manifestations.

Objectives: To describe the clinical, virological, and biological characteristics of the disease and identify the factors associated with severe presentations.

Study design: This prospective multicenter study recruited consecutive hospitalized patients with confirmed A(H1N1)pdm2009 disease. Clinical, virological and biological assessments were carried out at inclusion and 30 days post-inclusion. Disease manifestations were assessed by an adjudication committee using pre-identified definitions of complications and severity scores.

Results: The study analyzed from November 30th, 2009 to February 8th, 2010, 40 hospitalized patients, 21 children and 19 adults. Eighteen (45%) were considered to have severe presentations. Except age, main characteristics in children and adults did not differ. The majority (18/21) of children and all adults had a respiratory presentation; extra-respiratory manifestations tended to be more frequent in children (12 vs. 6, P=0.10). Two children against 5 adults presented acute respiratory distress syndrome (ARDS, P=0.23), but more children suffered respiratory failure (7 vs. 1, P=0.046) without ARDS. At day 30, one death had occurred in each group. The main factor associated with non-severe presentation was an early (<48 h) implementation of oseltamivir treatment (P=0.038).

Conclusions: Although the study failed to achieve its main objective, due mainly to the difficulty of carrying a study of this nature in the midst of a pandemic, it allowed the description of a panel of unusual and complicated forms and confirmed the added value of early oseltamivir treatment in limiting severity in hospitalized children and adults.

Keywords: A(H1N1)pdm2009 virus; Complication; Influenza; Pandemic; Severity.