The clinical epidemiology, management, and outcomes of patients diagnosed with encephalitis in North Carolina, 2015–2020

Abstract

ABSTRACT Historically, the underlying cause of encephalitis was often not identified, even though the condition was responsible for substantial morbidity and mortality. The past decade, however, has witnessed the establishment of consensus case definitions and management guidelines, accompanied by rapid advances in molecular diagnostic techniques. The objective of this study was to describe the epidemiology of and routine care practices for patients diagnosed with encephalitis at a large academic tertiary referral hospital. A retrospective analysis of adults and children admitted to the University of North Carolina Medical Center between 2015 and 2020 was conducted. Cases of interest were identified by ICD9 and ICD10 codes with a diagnosis of encephalitis confirmed through record review. One-third (82, 31.6%) of the cohort did not have a lumbar puncture performed. Of the 177 patients who had a diagnostic lumbar puncture performed, 87 (49.2%) cases were a result of a confirmed infectious pathogen. Herpes simplex virus (HSV)-1 ( n = 9) and HSV-2 ( n = 12) were the most common infectious causes, followed by varicella zoster virus (VZV) ( n = 16) and Toxoplasma gondii ( n = 5). There were no confirmed cases of enterovirus or arboviral diseases, but less than half of patients were tested for these pathogens. The case fatality rate was 10.7% ( n = 19) overall and 12.6% ( n = 11) in those with infectious causes. Despite advances in diagnostics, a high proportion of cases ( n = 75, 42.0%) were still classified as idiopathic. The use of order sets and/or multiplex testing (i.e., “encephalitis panel”) may improve the diagnosis of infectious encephalitis. IMPORTANCE Despite the relatively high mortality and the difficulty in diagnosis, nearly one-third of patients hospitalized with a documented diagnosis of encephalitis did not undergo a lumbar puncture (LP). When an LP was performed, pathogen-specific testing was greatly underutilized. Infectious etiologies were most common, but over 40% of cases were idiopathic at discharge. These findings suggest that there is a substantial opportunity to improve the quality of care through more accurate and timely diagnosis.