How should we define a 'good' outcome from encephalitis? A systematic review of the range of outcome measures used in the long-term follow-up of patients with encephalitis.

INTRODUCTION: Encephalitis is typically caused by infection or autoimmunity. Most survivors suffer complex neurological and psychiatric sequelae. Standardised outcome measures are needed for accurate interpretation of observational studies and clinical trials. Step one in this process is understanding the strengths and weaknesses of those in use.
METHODS: We performed a systematic literature review searching six databases. One reviewer screened titles and abstracts, and two reviewers determined if shortlisted full-text articles met inclusion criteria. Key data were extracted from these papers and presented as a narrative summary.
RESULTS: Thirty-seven outcome measures were used for 3,133 patients across the 35 included papers, of which, only one was developed for encephalitis. The outcome measures used in most patients were the Glasgow Outcome Score used in 1,436 (46%), Barthel Index used in 1,173 (37%), Euro-QoL-5D used in 1,107 (35%) and modified Rankin Scale used in 1,034 (33%).
CONCLUSION: Most of the 37 measures assessed a single category of sequelae using 5-8-point scales and were not validated for use in encephalitis. Research is needed to develop a composite outcome measure for use in clinical practice and a core-outcomes set for use in clinical trials. For now, the Liverpool Outcome Score offers a good choice for clinicians. © Royal College of Physicians 2022. All rights reserved.