Herpes simplex encephalitis (HSE) is the most common form of sporadic encephalitis worldwide and remains a devastating disease. However, the number of long-term nationwide studies of HSE is sparse. The aim of this study is to investigate incidence, patient characteristics, and mortality of first-time hospital-admitted adult HSE patients in Denmark during the period 2004-2014.
The Danish National Registry of Patients (DNRP) was used to identify all hospitalized patients, age 14 and above, with a diagnosis indicating HSE according to the International Classification of Diseases, tenth revision (ICD-10) during the study period. The ICD-10 codes defining the study population were; DB004 “Herpes Simplex Virus (HSV) Encephalitis”, DB004A”HSV Meningoencephalitis”, DG051E “Encephalitis Herpetica”. By this, we were able to calculate the incidence of HSE relating the number of patients with HSE to the population in Denmark in the respective years based on data from Statistics Denmark and to compute the proportion of HSE cases within categories of demographic variables. To calculate overall and 30-days mortality HSE patients were followed from date of first HSE diagnosis until death, emigration or end of study-period.
10-year period, we identified a total of 421 adult patients with ICD-10 codes
indicating encephalitis, in a preliminary analysis. A total of 369 were primary
diagnoses. The distribution of diagnoses was; DB004: 311, DB004A: 35, and
DG051E: 23. This corresponds to an incidence of HSE of 6.72 cases per million
population per year. Of these, 55.5 %
were women (n=206). The median age was 59 with interquartile range of 43-72
The 30-day mortality rate was 7.1% (95% CI: 4.9;10.2) and the 5-year mortality rate was 25.6% (95% CI: 21.2;30.7) (Fig. 2). The specific HSE diagnosis code DB004 was associated (tendency) with a higher mortality than the diagnoses DB004A and DG051E (p=0.052).
Using DNPR-data, we were able to identify a nationwide cohort of HSE patients with demographic data corresponding to earlier findings. The disease remains associated with a high mortality especially regarding the specific HSE diagnosis “HSV Encephalitis”.
L. K. Jørgensen,
L. Østergaard, None
M. Nørgaard, None
T. Mogensen, None