Predictors of outcome in acute encephalitis

Abstract

Objective: To investigate predictors of outcome in patients with all-cause encephalitis receiving care in the intensive care unit.

Methods: A retrospective analysis of encephalitis cases at The Johns Hopkins Hospital and Johns Hopkins Bayview Medical Center was performed. Using multivariate logistic regression analysis, we examined mortality and predictors of good outcome (defined as modified Rankin Scale scores of 1-3) and poor outcome (scores 4 and 5) in those surviving to hospital discharge.

Results: In our cohort of 103 patients, the median age was 52 years (interquartile range 26), 52 patients (50.49%) were male, 28 patients (27.18%) had viral encephalitis, 19 (18.45%) developed status epilepticus (SE), 15 (14.56%) had cerebral edema, and 19 (18.45%) died. In our multivariate logistic regression analysis, death was associated with cerebral edema (odds ratio [OR] 18.06, 95% confidence interval [CI] 3.14-103.92), SE (OR 8.16, 95% CI 1.55-43.10), and thrombocytopenia (OR 6.28, 95% CI 1.41-28.03). Endotracheal intubation requirement with ventilator support was highly correlated with death (95%). In addition, in those patients who survived, viral, nonviral, and unknown causes of encephalitis were less likely to have a poor outcome at hospital discharge compared with an autoimmune etiology (viral encephalitis: OR 0.09, 95% CI 0.01-0.57; nonviral encephalitis: OR 0.02, 95% CI 0.01-0.31; unknown etiology: OR 0.18, 95% CI 0.04-0.91).

Conclusions: Our study suggests that predictors of death in patients with encephalitis comprise potentially reversible conditions including cerebral edema, SE, and thrombocytopenia. Further prospective studies are needed to determine whether aggressive management of these complications in patients with encephalitis improves outcome.

Figure 1. Study population and etiologies of encephalitis

One hundred three of the 487 patients in the encephalitis database at The Johns Hopkins Hospital and Johns Hopkins Bayview Medical Center met inclusion criteria. Patients were categorized as viral, infectious nonviral (including bacterial and fungal), autoimmune, and unknown causes of encephalitis. *Case definition of encephalitis: admitted to hospital with encephalopathy and ≥2 of the following: fever (≥38°C), seizures, and/or focal neurologic findings (with evidence of brain parenchyma involvement), CSF pleocytosis (>5 WBCs/mm³), EEG findings compatible with encephalitis, and abnormal neuroimaging in keeping with encephalitis. Exclusion criteria included delirium or encephalopathy secondary to sepsis, toxic or metabolic causes (hypoglycemia, electrolyte disturbances), or primary psychiatric illness. Ab = antibody; ADEM = acute disseminated encephalomyelitis; HHV6 = human herpesvirus 6; ICU = intensive care unit; NMDAR = NMDA receptor; WBC = white blood cell.