[Study of respiratory influenza A H1N1 Virus (pH1N1) in hospitalized children in the pandemic year. Experience in 34 centers in Argentina].

INTRODUCTION

In Argentina, pandemic influenza pH1N1 caused nearly 10,000 confirmed cases with high impact in pediatrics.

OBJECTIVES

To describe clinical and epidemiological characteristics and analyse the risk factor of lethality in children hospitalized with infection pH1N1 confirmed by PCR.

POPULATION AND METHODS

We identifed all suspected cases (according to Ministry of health) in 34 centers and we included all the confirmed cases of 0-18 years from 1/4/09 to 31/8/09 in a retrospective cohort study. The viral diagnosis was confirmed by RT-PCR method. Data are expressed in percentages, average, median, standard deviation, and range (IQR) as appropriate; and as a measure of association, relative risk (RR), with 95% confidence interval (95%CI). Multiple logistic regression was conducted to determine the independent risk predictors.

RESULTS

Total number of suspected cases were: 2367; PCR was performed to 47.8% (n: 1131) being positive for pH1N1 65.5% (n: 741/1131); 57.2% males; 61.5% <24 months, median age: 14 months (IQR 6-46 months); 45.1% with underlying disease; more frequent clinical pictures were: pneumonia (39,7%) and bronchiolitis 25.8%; Case-fatality rate: 5.9% (44/741). Mortality risk factors were [RR (95%CI)]: neurological disease [5.00 (2.84-8.81)], genetic disease [3.67 (1.58-8.52)], malnutrition [3,07 (1.46-6.48)] and prematurity [2.28 (1.14-4.56)]. Independent mortality predictor: neurological disease [3.84 (1.81-8.14)]. No significant association between age, chronic respiratory disease, immunosuppression and viral co-infection with lethality was observed.

CONCLUSIONS

Almost half of children with pH1N1 infection had underlying disease; the neurological condition was a separate CFR predictor.