jueves, 25 de septiembre de 2014

Influenza-Associated Hospitalizations, Singapore, 2004–2008 and 2010–2012 - Volume 20, Number 10—October 2014 - Emerging Infectious Disease journal - CDC

full-text ►

Influenza-Associated Hospitalizations, Singapore, 2004–2008 and 2010–2012 - Volume 20, Number 10—October 2014 - Emerging Infectious Disease journal - CDC

CDC - Centers for Disease Control and Prevention - CDC 24/7: Saving Lives. Protecting People.™

Volume 20, Number 10—October 2014


Influenza-Associated Hospitalizations, Singapore, 2004–2008 and 2010–2012

Li Wei AngComments to Author , Cindy Lim, Vernon Jian Ming Lee, Stefan Ma, Wei Wei Tiong, Peng Lim Ooi, Raymond Tzer Pin Lin, Lyn James, and Jeffery Cutter
Author affiliations: Ministry of Health, Singapore (L.W. Ang, C. Lim, V.J.M. Lee, S. Ma, W.W. Tiong, P.L. Ooi, R.T.P. Lin, L. James, J. Cutter)Ministry of Defence, Singapore (V.J.M. Lee)


Studies of influenza-associated hospitalizations in tropical settings are lacking. To increase understanding of the effect of influenza in Singapore, we estimated the age-specific influenza-associated hospitalizations for pneumonia and influenza during 2004–2008 and 2010–2012. The rate of hospitalization was 28.3/100,000 person-years during 2004–2008 and 29.6/100,000 person-years during 2010–2012. The age-specific influenza-associated hospitalization rates followed a J-shaped pattern: rates in persons >75 years of age and in children <6 months of age were >47 times and >26 times higher, respectively, than those for persons 25–44 years of age. Across all ages during these 2 study periods, ≈12% of the hospitalizations for pneumonia and influenza were attributable to influenza. The rates and proportions of hospitalizations attributable to influenza, particularly among the very young and the elderly, are considerable in Singapore and highlight the importance of vaccination in protecting populations at risk.
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 (15), and others have documented influenza-associated hospitalizations in subtropical regions, mostly in Hong Kong, China (68).
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.


  1. Thompson WWShay DKWeintraub EBrammer LBridges CBCox NJInfluenza-associated hospitalizations in the United States. JAMA.2004;292:133340DOIPubMed
  2. Mullooly JPBridges CBThompson WWChen JWeintraub EJackson LAVaccine Safety Datalink Adult Working GroupInfluenza- and RSV-associated hospitalizations among adults. Vaccine2007;25:84655DOIPubMed
  3. Scuffham PAEstimating influenza-related hospital admissions in older people from GP consultation data. Vaccine2004;22:285362.DOIPubMed
  4. Azziz-Baumgartner ECabrera AMCheng PYGarcia EKusznierz GCalli RIncidence of influenza-associated mortality and hospitalizations in Argentina during 2002–2009. Influenza Other Respir Viruses. 2013;7:710–7.
  5. Newall ATWood JGMacintyre CRInfluenza-related hospitalisation and death in Australians aged 50 years and older. Vaccine2008;26:213541.DOIPubMed
  6. Chiu SSLau YLChan KHWong WHPeiris JSInfluenza-related hospitalizations among children in Hong Kong. N Engl J Med2002;347:2097103.DOIPubMed
  7. Wong CMYang LChan KPLeung GMChan KHGuan YInfluenza-associated hospitalization in a subtropical city. PLoS Med2006;3:e121.DOIPubMed
  8. Yang LWang XLChan KPCao PHLau HYPeiris JSHospitalisation associated with the 2009 H1N1 pandemic and seasonal influenza in Hong Kong, 2005 to 2010. Euro Surveill2012;17:20309 .PubMed
  9. Lee VJYap JOng JBChan KPLin RTChan SPInfluenza excess mortality from 1950–2000 in tropical Singapore. PLoS ONE2009;4:e8096.DOIPubMed
  10. Yang LMa SChen PYHe JFChan KPChow AInfluenza associated mortality in the subtropics and tropics: results from three Asian cities. Vaccine.2011;29:890914DOIPubMed
  11. Viboud CAlonso WJSimonsen LInfluenza in tropical regions. PLoS Med2006;3:e89DOIPubMed
  12. Chow AMa SLing AEChew SKInfluenza-associated deaths in tropical Singapore. Emerg Infect Dis2006;12:11421DOIPubMed
  13. Ministry of Health. Singapore. Statistics: top 10 conditions of hospitalisation [cited 2014 Jul22].http://www.moh.gov.sg/content/moh_web/home/statistics/Health_Facts_Singapore/Top_10_Conditions_of_Hospitalisation.html
  14. Department of Statistics, Ministry of Trade and Industry, Republic of Singapore. Population trends 2013 [cited 2014 Apr 12].http://www.singstat.gov.sg/publications/publications_and_papers/population_and_population_structure/population2013.pdf
  15. Kostova DReed CFinelli LCheng PYGargiullo PMShay DKInfluenza illness and hospitalizations averted by influenza vaccination in the United States, 2005–2011. PLoS ONE2013;8:e66312DOIPubMed
  16. Centers for Disease Control and PreventionEstimated influenza illnesses and hospitalizations averted by influenza vaccination—United States, 2012–13 influenza season. MMWR Morb Mortal Wkly Rep2013;62:9971000 .PubMed
  17. Maciosek MVSolberg LICoffield ABEdwards NMGoodman MJInfluenza vaccination health impact and cost effectiveness among adults aged 50 to 64 and 65 and older. Am J Prev Med2006;31:729DOIPubMed
  18. Allsup SHaycox ARegan MGosney MIs influenza vaccination cost effective for healthy people between ages 65 and 74 years? A randomised controlled trial. Vaccine2004;23:63945 .PubMed
  19. Nichol KLGoodman MCost effectiveness of influenza vaccination for healthy persons between ages 65 and 74 years. Vaccine2002;20:S214.DOIPubMed
  20. Nichol KLMargolis KLWuorenma JVon Sternberg TThe efficacy and cost effectiveness of vaccination against influenza among elderly persons living in the community. N Engl J Med1994;331:77884DOIPubMed
  21. Hoshi SLKondo MHonda YOkubo ICost-effectiveness analysis of influenza vaccination for people aged 65 and over in Japan. Vaccine.2007;25:651121DOIPubMed
  22. Lang POMendes ASocquet JAssir NGovind SAspinall REffectiveness of influenza vaccine in aging and older adults: comprehensive analysis of the evidence. Clin Interv Aging2012;7:5564DOIPubMed
  23. Osterholm MTKelley NSSommer ABelongia EAEfficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis. [Erratum in: Lancet Infect Dis. 2012;12:655]Lancet Infect Dis2012;12:3644DOIPubMed
  24. Deans GDStiver HGMcElhaney JEInfluenza vaccines provide diminished protection but are cost-saving in older adults. J Intern Med.2010;267:2207DOIPubMed
  25. Jefferson TDi Pietrantonj CAl-Ansary LAFerroni EThorning SThomas REVaccines for preventing influenza in the elderly. Cochrane Database Syst Rev2010;2:CD004876 .PubMed
  26. Hurwitz ESHaber MChang AShope TTeo SGinsberg MEffectiveness of influenza vaccination of day care children in reducing influenza-related morbidity among household contacts. JAMA2000;284:167782 and. DOIPubMed
  27. Reichert TASugaya NFedson DSGlezen WPSimonsen LTashiro MThe Japanese experience with vaccinating schoolchildren against influenza. N Engl J Med2001;344:88996DOIPubMed
  28. Ghendon YZKaira ANElshina GAThe effect of mass influenza immunization in children on the morbidity of the unvaccinated elderly. Epidemiol Infect2006;134:718DOIPubMed
  29. Cohen SAChui KKNaumova ENInfluenza vaccination in young children reduces influenza-associated hospitalizations in older adults, 2002–2006.J Am Geriatr Soc2011;59:32732DOIPubMed
  30. Centers for Disease Control and PreventionPrevention and control of seasonal influenza with vaccines. Recommendations of the Advisory Committee on Immunization Practices—United States, 2013–2014. [Erratum in MMWR Recomm Rep. 2013;62:906]MMWR Recomm Rep.2013;62(RR-07):143.
  31. Chiu SSChan KHChen HYoung BWLim WWong WHVirologically confirmed population-based burden of hospitalization caused by influenza A and B among children in Hong Kong. Clin Infect Dis2009;49:101621DOIPubMed
  32. Silvennoinen HPeltola VVainionpää RRuuskanen OHeikkinen TIncidence of influenza-related hospitalizations in different age groups of children in Finland: a 16-year study. Pediatr Infect Dis J2011;30:e248DOIPubMed
  33. Poehling KAEdwards KMWeinberg GASzilagyi PStaat MAIwane MKThe underrecognized burden of influenza in young children. N Engl J Med.2006;355:3140DOIPubMed
  34. Dawood FSFiore AKamimoto LBramley AReingold AGershman KBurden of seasonal influenza hospitalization in children, United States, 2003 to 2008. J Pediatr2010;157:80814DOIPubMed
  35. Neuzil KMMellen BGWright PFMitchel EF JrGriffin MRThe effect of influenza on hospitalizations, outpatient visits, and courses of antibiotics in children. N Engl J Med2000;342:22531DOIPubMed
  36. Fraaij PLHeikkinen TSeasonal influenza: the burden of disease in children. Vaccine2011;29:75248DOIPubMed
  37. Hong Kong Centre for Health Protection. Seasonal influenza vaccination survey for the 2012/13 season. Communicable Diseases Watch2013;10:74–5 [cited 2014 Jul 4]. http://www.chp.gov.hk/en/guideline1_year/29/134/112.html
  38. Lu PJSantibanez TAWilliams WWZhang JDing HBryan LSurveillance of influenza vaccination coverage—United States, 2007–08 through 2011–12 influenza seasons. MMWR Surveill Summ2013;62(Suppl 4):128 .PubMed
  39. Zimmerman RKRecent changes in influenza epidemiology and vaccination recommendations. J Fam Pract2005;54(Suppl):S18 .PubMed
  40. Ministry of Health. Singapore. Statistics: healthcare institution statistics [cited 2014 Apr 12].http://www.moh.gov.sg/content/moh_web/home/statistics/healthcare_institutionstatistics.html



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
DOI: 10.3201/eid2010.131768

No hay comentarios:

Publicar un comentario