Encephalitis Hospitalization Rates and Inpatient Mortality in the United States, 2000-2010

Abstract

BackgroundEncephalitis rates by etiology and acute-phase outcomes for encephalitis in the 21st century are largely unknown. We sought to evaluate cause-specific rates of encephalitis hospitalizations and predictors of inpatient mortality in the United States.MethodsUsing the Nationwide Inpatient Sample (NIS) from 2000 to 2010, a retrospective observational study of 238,567 patients (mean [SD] age, 44.8 [24.0] years) hospitalized within non-federal, acute care hospitals in the U.S. with a diagnosis of encephalitis was conducted. Hospitalization rates were calculated using population-level estimates of disease from the NIS and population estimates from the United States Census Bureau. Adjusted odds of mortality were calculated for patients included in the study.ResultsIn the U.S. from 2000–2010, there were 7.3±0.2 encephalitis hospitalizations per 100,000 population (95% CI: 7.1–7.6). Encephalitis hospitalization rates were highest among females (7.6±0.2 per 100,000) and those <1 year and >65 years of age with rates of 13.5±0.9 and 14.1±0.4 per 100,000, respectively. Etiology was unknown for approximately 50% of cases. Among patients with identified etiology, viral causes were most common (48.2%), followed by Other Specified causes (32.5%), which included predominantly autoimmune conditions. The most common infectious agents were herpes simplex virus, toxoplasma, and West Nile virus. Comorbid HIV infection was present in 7.7% of hospitalizations. Average length of stay was 11.2 days with mortality of 5.6%. In regression analysis, patients with comorbid HIV/AIDS or cancer had increased odds of mortality (odds ratio [OR] = 1.70; 95% CI: 1.30–2.22 and OR = 2.26; 95% CI: 1.88–2.71, respectively). Enteroviral, postinfectious, toxic, and Other Specified causes were associated with lower odds vs. herpes simplex encephalitis.ConclusionsWhile encephalitis and encephalitis-related mortality impose a considerable burden in the U.S. in the 21st Century, the reported demographics of hospitalized encephalitis patients may be changing.

Herpes Simplex Virus-1 Encephalitis in Adults: Pathophysiology, Diagnosis, and Management

“…The incidence of HSVE worldwide is estimated to be between 2 and 4 cases/1,000,000 [44], and the incidence in the USA is similar [53]. There is a bimodal distribution with peak incidence in the very young (up to 3 years of age), and again in adults aged > 50 years, but the majority of cases occur in those over 50, with both sexes equally affected [44,[54][55][56].…”

State-of-the-Art Microbiologic Testing for Community-Acquired Meningitis and Encephalitis

“…As such, meningitis and encephalitis are uncommon, affecting 4 to 30 people/100,000 and 3 to 7 people/100,000, respectively, in developed countries each year, but the morbidity, mortality, and costs are substantial (4,8,(10)(11)(12). For example, there are Ͼ70,000 meningitis-related hospitalizations in the United States each year, with an in-hospital mortality rate of 0.4 to 11.4% and cost of $1.2 billion (17).…”

“…The frequency of most microorganisms associated with meningitis also varies by host and geographic factors, season, and exposure history (21). For example, the type and incidence of arboviral infections vary markedly between geographic regions and both seasonally and year to year in regions of endemicity, depending on the climate, vector and reservoir population dynamics, and human behavior patterns (8,21). Thus, arboviral infections are rare in the United Kingdom and northern Europe, occur seasonally in the summer and autumn in southern Europe and the United States, and occur year-round in the tropics (21).…”

“…Treatment, prognosis, and outcomes vary greatly between patients and depend primarily on the timely initiation of therapy based on identification of the underlying cause of inflammation, since clinical signs and symptoms are not pathogen specific (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Nonetheless, many meningitis (15 to 60%) and encephalitis (40 to 70%) patients fail to receive a specific etiologic diagnosis leading to unnecessary or inappropriate treatment and potentially avoidable adverse events (8,(10)(11)(12). To address this issue, we discuss common reasons for failing to make an etiologic diagnosis in community-acquired meningitis and encephalitis and make general recommendations for the use of current and emerging microbiologic tests to maximize pathogen identification and appropriate treatment.…”

Vaccinations for Neuroinfectious Disease: A Global Health Priority

“…For instance, herpes simplex virus (HSV) is the most common identifiable cause of viral encephalitis, responsible for about 13.8 % of all cases [52]. Approximately 90 % cases of HSVencephalitis are caused by HSV-1, and 10 % by HSV-2.…”