Ahead of Print -Influenza-Associated Hospitalizations, Singapore, 2004–2008 and 2010–2012 - Volume 20, Number 10—October 2014 - Emerging Infectious Disease journal - CDC
Volume 20, Number 10—October 2014
Influenza-Associated Hospitalizations, Singapore, 2004–2008 and 2010–2012
Seasonal influenza causes a substantial burden of illness worldwide. Infections can lead to severe illness that requires hospital care and can occasionally lead to death. Several studies have documented influenza-associated hospitalizations in countries with primarily temperate climates, such as the United States (1–5), and others have documented influenza-associated hospitalizations in subtropical regions, mostly in Hong Kong, China (6–8).
In the tropics, the spread of influenza is different from that in temperate regions because of the unique tropical climate and lack of clear climatic seasons (9,10). The baseline incidence of influenza infection is high, and >1 seasonal epidemic occurs each year (11). As documented in studies on influenza-associated deaths in Singapore (9,12), the effect of influenza epidemics in the tropics is comparable to its effect in other climatic regions. However, studies on influenza-associated hospitalizations in tropical settings are lacking. Such studies can provide an understanding of the pattern of hospitalizations and severe illness that is valuable in guiding public health policies.
Laboratory testing of specimens and virologic confirmation of influenza virus infections are not typically conducted for all patients and deaths; thus, the estimation of illness attributable to influenza cannot be based on reported episodes alone. Influenza can precipitate or exacerbate other respiratory and circulatory conditions, and there is a wide spectrum of clinical pathways and outcomes for influenza-associated conditions and complications. Pneumonia was ranked fifth in the list of top 10 conditions for hospitalization in Singapore in 2012 (13). There is a need to estimate the effect of influenza on health care utilization in terms of hospitalization for pneumonia and influenza.
Singapore has a robust data collection system, which facilitates the integration of databases from virologic surveillance for influenza and hospital systems. The aim of our study was to examine the influenza-associated hospitalization rates and proportions of pneumonia and influenza hospitalizations in Singapore. Age groups spanning <6 months to ≥75 years of age were examined to further identify the populations at greatest risk for influenza-associated hospitalizations.
Ms Ang is an assistant director in the Communicable Diseases Analytics unit of the Biostatistics and Research Branch, Epidemiology and Disease Control Division, at the Ministry of Health, Singapore. Her research interests include statistical applications, disease epidemiology, and public health surveillance.
We greatly appreciate and acknowledge the contribution of staff at the public acute-care hospitals, government primary care clinics, and private general practitioner clinics involved in the virologic surveillance for influenza. We thank the Research and Strategic Planning Division of the Health Promotion Board for sharing findings from the Health Behavior Surveillance of Singapore on the proportion of adults in Singapore who reported having been vaccinated against influenza.
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Suggested citation for this article: Ang LW, Lim C, Lee VJM, Ma S, Tiong WW, Ooi PL, et al. Influenza-associated hospitalizations, Singapore, 2004–2008 and 2010–2012. Emerg Infect Dis. 2014 Oct [date cited]. http://dx.doi.org/10.3201/eid2010.131768