title: Real-time characterization of risks of death associated with the Middle East respiratory syndrome (MERS) in the Republic of Korea, 2015.
abstract: BACKGROUND
  An outbreak of the Middle East respiratory syndrome (MERS), comprising 185 cases linked to healthcare facilities, occurred in the Republic of Korea from May to July 2015. Owing to the nosocomial nature of the outbreak, it is particularly important to gain a better understanding of the epidemiological determinants characterizing the risk of MERS death in order to predict the heterogeneous risk of death in medical settings.
  
  
  METHODS
  We have devised a novel statistical model that identifies the risk of MERS death during the outbreak in real time. While accounting for the time delay from illness onset to death, risk factors for death were identified using a linear predictor tied to a logit model. We employ this approach to (1) quantify the risks of death and (2) characterize the temporal evolution of the case fatality ratio (CFR) as case ascertainment greatly improved during the course of the outbreak.
  
  
  RESULTS
  Senior persons aged 60 years or over were found to be 9.3 times (95% confidence interval (CI), 5.3-16.9) more likely to die compared to younger MERS cases. Patients under treatment were at a 7.8-fold (95% CI, 4.0-16.7) significantly higher risk of death compared to other MERS cases. The CFR among patients aged 60 years or older under treatment was estimated at 48.2% (95% CI, 35.2-61.3) as of July 31, 2015, while the CFR among other cases was estimated to lie below 15%. From June 6, 2015, onwards, the CFR declined 0.3-fold (95% CI, 0.1-1.1) compared to the earlier epidemic period, which may perhaps reflect enhanced case ascertainment following major contact tracing efforts.
  
  
  CONCLUSIONS
  The risk of MERS death was significantly associated with older age as well as treatment for underlying diseases after explicitly adjusting for the delay between illness onset and death. Because MERS outbreaks are greatly amplified in the healthcare setting, enhanced infection control practices in medical facilities should strive to shield risk groups from MERS exposure.
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 1538902, Japan. mizumotokenji@gmail.com.
authors.forename: Kenji
authors.initials: K
authors.lastname: Mizumoto
authors.affiliation: Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1130033, Japan. akr.endo@outlook.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Endo
authors.affiliation: School of Public Health, Georgia State University, Atlanta, Georgia, USA. gchowell@gsu.edu.|Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, Maryland, USA. gchowell@gsu.edu.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Chowell
authors.affiliation: Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1130033, Japan. yuichiromiyamatsu@gmail.com.|CREST, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama, 332-0012, Japan. yuichiromiyamatsu@gmail.com.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Miyamatsu
authors.affiliation: Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1130033, Japan. saitohm@ism.ac.jp.|CREST, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama, 332-0012, Japan. saitohm@ism.ac.jp.|The Institute of Statistical Mathematics, Tachikawa, Tokyo, Japan. saitohm@ism.ac.jp.
authors.forename: Masaya
authors.initials: M
authors.lastname: Saitoh
authors.affiliation: Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1130033, Japan. nishiurah@m.u-tokyo.ac.jp.|CREST, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama, 332-0012, Japan. nishiurah@m.u-tokyo.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiura
mesh_terms: D018352:Coronavirus Infections / Q000401:mortality*; D003428:Cross Infection / Q000401:mortality*; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D016019:Survival Analysis