Incidence and mortality of herpes simplex encephalitis in Denmark: A nationwide registry-based cohort study

• Published in: The Journal of infection Vol. 74; no. 1; pp. 42 - 49
• Main Authors: Jørgensen, Laura Krogh, Dalgaard, Lars Skov, Østergaard, Lars Jørgen, Nørgaard, Mette, Mogensen, Trine Hyrup
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2017
• Subjects: Aged; Cohort Studies; Comorbidity; Denmark - epidemiology; Encephalitis, Herpes Simplex - epidemiology; Encephalitis, Herpes Simplex - mortality; Encephalitis, Herpes Simplex - virology; Epidemiology; Female; Herpes Simplex - complications; Herpes Simplex - epidemiology; Herpes Simplex - mortality; Herpes Simplex - virology; Herpes simplex encephalitis; Herpes simplex virus; Hospitalization; Humans; Incidence; Infectious Disease; Male; Middle Aged; Mortality; Prognosis; Registries; Retrospective Studies; Viral encephalitis; Prognosis; Comorbidity; Mortality; Viral encephalitis; Epidemiology; Herpes simplex virus; Herpes simplex encephalitis; Incidence
• ISSN: 0163-4453; 1532-2742
• DOI: 10.1016/j.jinf.2016.09.004

Summary Objectives We aimed to investigate the incidence and mortality of herpes simplex encephalitis (HSE) in a nationwide cohort. Methods From the Danish National Patient Registry, we identified all adults hospitalised with a first-time diagnosis of HSE in Denmark during 2004–2014. The HSE diagnoses were verified using medical records and microbiological data. Patients were followed for mortality through the Danish Civil Registry System. We estimated age-standardised incidence rates of HSE and 30-day, 60-day, and 1-year cumulative mortality. Furthermore, we assessed whether calendar year, age, gender, level of comorbidity, virus type, and department type was associated with HSE mortality. Results We identified a total of 230 cases of HSE. Median age was 60.7 years (interquartile range: 49.3–71.6). The overall incidence rate was 4.64 cases per million population per year (95% confidence interval: 4.06–5.28). The cumulative mortality within 30 days, 60 days, and 1 year of the HSE admission was 8.3%, 11.3%, and 18.6%, respectively. Advanced age and presence of comorbidity were associated with increased 60-day and 1-year mortality. Conclusions This nationwide study of verified HSE found a higher incidence than reported in previous nationwide studies. Presence of comorbidity was identified as a novel adverse prognostic factor. Mortality rates following HSE remain high.