Intravenous immunoglobulin treatment in childhood encephalitis (IgNiTE): a randomised controlled trial

Objective To investigate whether intravenous immunoglobulin (IVIG) improves neurological outcomes in children with encephalitis when administered early in the illness. Design Phase 3b multicentre, double-blind, randomised placebo-controlled trial. Setting Twenty-one hospitals in the UK. Participants Children aged 6 months to 16 years with a diagnosis of acute or subacute encephalitis, with a planned sample size of 308. Intervention Two doses (1 g/kg/dose) of either IVIG or matching placebo given 24–36 hours apart, in addition to standard treatment. Main outcome measure The primary outcome was a ‘good recovery’ at 12 months after randomisation, defined as a score of≤2 on the Paediatric Glasgow Outcome Score Extended. Secondary outcome measures The secondary outcomes were clinical, neurological, neuroimaging and neuropsychological results, identification of the proportion of children with immune-mediated encephalitis, and IVIG safety data. Results 18 participants were recruited from 12 hospitals and randomised to receive either IVIG (n=10) or placebo (n=8) between 23 December 2015 and 26 September 2017. The study was terminated early following withdrawal of funding due to slower than anticipated recruitment, and therefore did not reach the predetermined sample size required to achieve the primary study objective; thus, the results are descriptive. At 12 months after randomisation, 9 of the 18 participants (IVIG n=5/10 (50%), placebo n=4/8 (50%)) made a good recovery and 5 participants (IVIG n=3/10 (30%), placebo n=2/8 (25%)) made a poor recovery. Three participants (IVIG n=1/10 (10%), placebo n=2/8 (25%)) had a new diagnosis of epilepsy during the study period. Two participants were found to have specific autoantibodies associated with autoimmune encephalitis. No serious adverse events were reported in participants receiving IVIG. Conclusions The IgNiTE (ImmunoglobuliN in the Treatment of Encephalitis) study findings support existing evidence of poor neurological outcomes in children with encephalitis. However, the study was halted prematurely and was therefore underpowered to evaluate the effect of early IVIG treatment compared with placebo in childhood encephalitis. Trial registration number Clinical Trials.gov NCT02308982; ICRCTN registry ISRCTN15791925.


INTRODUCTION
2][3] It is characterised by inflammation of the brain parenchyma causing neurological dysfunction which manifests acutely as altered mental state and can have long-term sequalae including neurological disability and seizures.][6][7][8][9][10] It often takes time to reach a definitive diagnosis, and a cause may not be found despite extensive investigation in at least one-fifth of children. 4 6 7 10 Encephalitis is more prevalent among children than adults, with an estimated incidence of 4.0-12.6 per 100 000 person years for children in high-income countries. 7 10-14There is a substantially higher burden of childhood encephalitis in regions such as southeast Asia where the Japanese encephalitis virus is endemic. 2 8 Childhood encephalitis carries

STRENGTHS AND LIMITATIONS OF THIS STUDY
⇒ This was the first ever multicentre, randomised controlled trial evaluating intravenous immunoglobulin treatment for all-cause encephalitis in children.⇒ The study had clinically meaningful endpoints and was run to a very high standard, with rigorous blinding procedures throughout.⇒ Recruitment to the study was limited by the strict inclusion and exclusion criteria, the limited time window for enrolment and lack of equipoise among clinicians.copyright.
Open access a significant mortality rate; this ranges from 5% to 13%, dependent on setting and aetiology. 4 8 10 15 16Approximately half of children who survive an episode of encephalitis will have long-term sequalae which may include neurological deficits, physical disability, cognitive impairment, neuropsychiatric disorders and epilepsy. 4 8 10 15 17-19hildhood encephalitis is therefore associated with a high global economic, healthcare and social burden. 1 3 8 15 20 While there is good evidence for the efficacy of aciclovir in the management of encephalitis caused by herpes simplex virus and varicella zoster virus, 21 22 there are limited therapeutic options for other types of childhood encephalitis and the mainstay of treatment is supportive care.][25][26] Furthermore, these therapies are often only implemented after a definitive autoimmune cause for encephalitis has been identified or all alternative diagnoses, including infectious, have been ruled out.
IVIG is used successfully in other inflammatory and neurological conditions in children 27 28 ; however, there have been no high-quality studies to support or refute its use in children with all types of encephalitis. 29 30Inflammation of the brain parenchyma is the common cause of altered neurological function in encephalitis, regardless of the aetiology, and it may therefore be postulated that interventions which attenuate the inflammation early in the illness are likely to have the greatest efficacy in reducing the severity of the acute illness, mortality and neurological sequalae of childhood encephalitis.
In this study, we set out to establish if early IVIG treatment, in addition to standard care, improves outcomes for children with encephalitis of all aetiologies.

Study design
IgNiTE was a randomised, double blinded, parallel arm, placebo-controlled study to compare early IVIG treatment with placebo in the treatment of childhood encephalitis in individuals aged 6 months to 16 years.It was conducted across 21 National Health Service (NHS) hospitals in the UK.Participants were followed up for 12 months after randomisation, with outcomes assessed during the acute admission, at 4-8 weeks after discharge from acute care, at 6 months after randomisation, and 12 months after randomisation.
The trial was prospectively registered with Clinical-Trials.gov (identifier NCT 02308982) on 5  The original trial protocol was published on 3 November 2016. 31The protocol was amended after the early termination of the trial to remove endpoints which could not be derived from the data collected and to update the statistical analysis section; the amended protocol is available in the online supplemental material.

Participants
Eligible participants were hospitalised children aged between 6 weeks and 16 years who met the case definition for encephalitis based on the consensus definition by the International Encephalitis Consortium, 32 where written informed consent was obtained from parents or guardians, and assent was given if appropriate.
Exclusion criteria were a high clinical suspicion of bacterial meningitis; prior receipt of IVIG during the admission or known contraindication to IVIG; traumatic brain injury; history of metabolic encephalopathy; stroke, toxic or hypertensive encephalopathy; pre-existing demyelinating disorder; significant renal impairment; hypercoagulable state; hyperprolinaemia; participation in another research trial involving an immunomodulatory treatment; pregnancy; any significant disease or disorder which may put the participants at risk because of participation in the trial, influence the result of the trial, or the participant's ability to participate in the trial; involvement in another research trial involving an investigational medicinal product (IMP) which has potential immunomodulatory or neuroprotective effects.

Intervention
Two doses of 1 g/kg/dose of either IVIG or a matching volume of placebo were given 24-36 hours apart, with the first dose administered as soon as possible after enrolment and within five working days from the suspicion of an encephalitis diagnosis.
The active treatment (IVIG) used in the study was privigen (100 mg/mL solution), manufactured and provided by CSL Behring.The placebo was a mixture of 0.9% saline and 0.1% human albumin solution, manufactured at the Royal Broadgreen and Liverpool Aseptic Production Unit, Liverpool, UK under cGMP conditions and its Manufacturer's Importer's Authorisation (IMP) licence.

Randomisation and blinding
Participants were randomised 1:1 to IVIG or placebo treatment after consent was obtained.Randomisation was stratified by age group (< 1 year, 1-4 years, 5-9 years, 10-14 years and ≥15 years) and steroid treatment at the time of randomisation, using stratified block randomisation with randomly varying block sizes.Randomisation was performed using a secure web-based randomisation system (Sortition) which was developed by the Clinical Trials Unit in the Nuffield Department of Primary Care Health Sciences, University of Oxford.Participants, their parents or guardians, clinical staff and all study staff (including staff involved in recruitment, administration of study treatment, data collection and entry, and laboratory analyses) were blind to the treatment allocation through the entire study period.Study monitors who were independent of the study and all site pharmacists were unblinded to ensure dispensing of the correct allocation and robust IMP management at each study site.The placebo and IVIG were visually identical, due to the additional of 0.1% human albumin solution to 0.9% in the placebo.

Primary outcome
The primary outcome was good recovery, which was defined as a score of 2 or less on the paediatric version of the Glasgow Outcome Score Extended (GOS-E Peds) at 12 months after randomisation.
The GOS-E Peds is based on the GOS-E, a gold standard for measuring outcomes in adults with traumatic brain injury.It is a validated tool for use in children, and provides a developmentally appropriate structured interview necessary to evaluate children across different age groups. 33Participants were assigned a GOS-E Peds score: 1-Upper Good Recovery, 2-Lower Good Recovery, 3-Upper Moderate Disability, 4-Lower Moderate Disability, 5-Upper Severe Disability, 6-Lower Severe Disability, 7-Vegetative State, and 8-Death.'Good recovery' was defined as a GOS-E Peds score of ≤2, and a score of >2 indicated 'poor recovery'.

Secondary outcomes
Secondary clinical outcomes included admission to intensive care unit, requirement for invasive ventilation, length of acute hospital stay, new diagnoses of epilepsy and need for antiepileptic treatment in the 12 months after randomisation.
Secondary neurological and functional outcomes comprised GOS-E Peds assessment at 6 months after randomisation, and Liverpool Outcome Score (LOS) assessment, Pediatric Quality of Life Score (PedsQL) assessment, Gross Motor Function and Classification System (GMFCS) assessment, Strengths and Difficulty Questionnaire (SDQ) assessment and Adaptive Behavior Assessment System-second edition (ABAS-II) assessment at 4-8 weeks after discharge from acute care and at 12 months after randomisation.
Secondary neuropsychological outcomes were cognitive assessment at 12 months after randomisation using the age-appropriate scales: The secondary neuroimmunology outcome was identification of autoantibodies.The antibodies tested for were for antibodies against live neurons, aquaporin 4, N-methyl-D-aspartate receptor, myelin oligodendrocyte glycoprotein (MOG), leucine-rich, glioma inactivated 1 (LGI1), and contactin-associated protein-like 2.
Secondary neuroimaging outcomes comprised assessment of CT or MRI brain scans performed as part of routine care during the acute illness, and follow-up scans performed at 6 months after randomisation in a subset of participants, where consent was provided.
Secondary safety outcomes included safety data obtained throughout the study, and a full blood count performed for all participants 24-48 hours following the second dose of the study treatment to monitor for haemolysis which has previously been described with high concentrations of IVIG treatment. 34Safety data comprised adverse events (AEs) and adverse events of special interest occurring in the first 5 days following receipt of each dose of the study drug, serious adverse events (SAEs) occurring up until 6 months after randomisation and serious adverse reactions occurring throughout the study period.Information on any deaths occurring up to 12 months after randomisation was also collected.
Further information regarding to the secondary outcomes is provided in the online supplemental material.

Protocol amendments
The IgNiTE study was halted in October 2017 after the withdrawal of funding due to slower than anticipated recruitment.This was despite the proposal of alternative strategies to deliver on the study objectives, including revision of the recruitment timeline to ensure that the objectives of this important clinical study could be met.Where possible, follow-up activities were completed for all participants who were already enrolled into the trial, as per the protocol.The protocol was amended to remove endpoints which could not be derived from the data collected and to update the statistical analysis section.

Statistical analysis
A sample size of 308 participants recruited over a 24-month period (154 per group, with approximate 10% attrition rate) was planned to achieve 90% power (at 5% level of significance) to detect at least a 20% clinically significant treatment difference from 43% in the 'good recovery' rate (defined as a GOS-E Peds score of ≤2) by 12 months after randomisation.This was based on the results of a large observational study on autoimmune encephalitis. 26t the time the trial was halted, only 18 participants had been recruited.The trial was therefore underpowered to perform hypothesis testing of outcomes, subgroup comparisons or sensitivity analyses.Therefore, all analyses performed were descriptive.The analyses were performed on the intention-to-treat population; this included all 18 participants who were randomised.In the analysis of the AEs, the population analysed were the 16 participants who received study treatment.

Patient and public involvement (PPI)
The Encephalitis Society was involved in the planning of this study, and the training of research nurses and study Table 1 summarises the baseline characteristics of participants by treatment arm.The mean age of the participants was 4.09 years (IQR 2.0-11.8),44% were male, and 89% were of white ethnicity.

Adaptive Behaviour Assessment System-Second Edition (ABAS-II)
Eight participants had an ABAS-II assessment at 4-8 weeks after discharge from acute care, and seven participants had an ABAS-II assessment at 12 months after randomisation (see table 4).At 4-8 weeks after discharge, five participants (28%; IVIG n=4/10 (40%), placebo n=1/8 (13%)) had an ABAS-II score that was either similar or higher than the average score of the normative population, and three participants (17%; IVIG n=2/10 (20%), placebo n=1/8 (13%)) had a score that was lower than the average score.At 12 months after randomisation, the same number of participants had a score that was below the average at 12 months after randomisation, but four participants (22%; IVIG n=3/10 (30%), placebo n=1/8 (13%)) had a score that was either similar or higher than the average score at this timepoint.

Autoantibody testing
Twelve participants (67%; IVIG n=7/10 (70%), placebo n=5/8 (63%)) had autoantibody testing.One participant (placebo n=1) was positive for LGI1 antibodies, and one participant (placebo n=1) was positive for MOG antibodies.Two additional participants (IVIG n=2) were positive for IgG binding to the surface of live neurons, indicating the presence of IgG antibodies binding to neurons, but negative for antibodies to the specific antigens tested, indicating the presence of undefined IgG antibodies that could be pathogenic.

Safety data
Ten serious AEs occurred in three participants in the placebo group and none in the IVIG group.None of the SAEs were judged to be related to the study treatment.One participant in the IVIG group reported an AE of special interest; the participant developed a fever during the IVIG infusion; however, this was judged to be unrelated to the study treatment.None of the participants experienced haemolysis following receipt of two doses of study treatment.No deaths occurred during the study period.

DISCUSSION
The IgNiTE study was terminated early due to slower than expected recruitment and was therefore unable to provide conclusive evidence regarding the efficacy of Open access IVIG in the treatment of childhood encephalitis.Thus, it remains unknown whether early administration of IVIG in children with all-cause encephalitis offers clinical benefit.While the IgNITE study was unable to address the primary study objective, the results do provide evidence of the poor outcomes experiences by many children with encephalitis.Almost a third of participants made a poor recovery based on GOS-E Peds assessment at 12 months after randomisation.Other measures of neurological outcomes consistently demonstrated a heavy burden of disability; 44% of patients had minor to severe sequalae at 12 months according to the LOS assessment, and the same proportion of patients experienced mild or severe impairment of gross motor function at the same timepoint.The proportion of children with functional impairments on the SDQ and ABAS-II assessments at 12 months after randomisation was lower, but this was likely due to fewer participants completing these assessments.
The results also demonstrate the impact of childhood encephalitis on healthcare systems.Over half of participants required admission to intensive care during the acute illness, and 90% of these children were intubated.The overall median length of acute hospital care for participants was 11 days, compared with a mean length of hospital stay of 1.64 days for children and young people following an emergency admission in the UK. 35urthermore, given the high proportion of participants with lasting disability, many children with encephalitis are likely require ongoing non-acute hospital care for neurorehabilitation.
These data are consistent with previous studies of childhood encephalitis in high-income settings.In a prospective Australian study involving 287 children with encephalitis, 49% of children required admission to intensive care, median length of hospitalisation was 11 days and 27% of children had moderate to severe neurodisability at hospital discharge. 4Of note, they used the adult Glasgow Outcome Score tool for assessment of outcomes and did not capture children with mild-to-moderate neurodisability, which may explain the lower proportion of children with reported neurodisability compared with the IgNiTE study.A meta-analysis evaluating long-term outcomes of childhood encephalitis reported 47% of children to have long-term sequalae in studies in highincome countries, although there was no standardised definition of sequalae used across these studies. 17

Limitations of the study
The main limitation of the IgNiTE study is that the predefined sample size was not met, and the primary study objective was therefore not achieved.The study initially planned to recruit 308 participants over a 24-month period.The sample size calculation was based on the anticipated number of annual encephalitis hospital admissions in the UK and the anticipated treatment effect of IVIG, based on a large observational study on autoimmune encephalitis. 26 36However, recruitment to the study was slower than expected.Of the 884 children assessed for eligibility, 63% (561) were excluded because they did not meet the case definition for encephalitis, suggesting that the use of strict diagnostic criteria may have precluded the inclusion of some children with clinically suspected encephalitis.A further 12.5% were excluded due to insufficient clinical results being available to satisfy the eligibility criteria within the time frame for participant enrolment.The initial screening form used did not capture the reason for exclusion; hence, this was not recorded for the first 10% of children assessed for eligibility.
Overall, 13% (115) of children were assessed to meet to inclusion criteria, but 55% (63) of these children fulfilled exclusion criteria and were thus ineligible.The main reasons for exclusion were prior or planned IVIG treatment as part of routine care (32%), and study timeline restrictions (24%).The use of IVIG as part of routine care demonstrates that some clinicians were already convinced of the benefit of IVIG in childhood encephalitis despite the lack of high-quality evidence and the fact that at the time the trial was undertaken, IVIG was not commissioned for routine use in acute childhood encephalitis.This highlights the importance of ensuring that there is equipoise among treating clinicians when conducting randomised controlled trials.
Recruitment to the trial was also impacted by a lower than anticipated consent rate.Of the 52 children who were eligible for enrolment, participation was declined in 65% of cases.This is not unexpected given the requirement for parents or guardians to provide informed consent at an exquisitely sensitive time for the family.Other factors which may have contributed to the low consent rate include the limited time frame for enrolment and the trial duration. 37inally, recruitment was impacted by delays in the participating NHS hospitals opening as recruitment sites, due primarily to shortages of research personnel and delays in local approval processes.Nine of the 21 participating hospitals did not recruit any particitpants during the study; 5 of these hospitals were open to recruitment for 6 months or less.

Lessons learned and future research
Further research is required to establish whether early IVIG is of therapeutic benefit in the treatment of childhood encephalitis, irrespective of the underlying aetiology.The IgNiTE study demonstrated the feasibility of conducting a randomised controlled trial to investigate this important question.Future studies should anticipate the recruitment challenges discussed above and consider strategies such as incorporating a pilot phase, using less strict entry criteria, allowing a wider time frame in which participants can be enrolled, and adopting approaches to optimise consent rates in eligible patients.

Conclusion
The IgNiTE study was terminated prematurely due to slow recruitment and therefore did not reach the Open access predetermined sample size required to evaluate the effect of IVIG compared with placebo in childhood encephalitis.However, the study results support existing evidence of poor neurological outcomes in many children with encephalitis.This provides further compelling evidence of the need for better treatments in childhood encephalitis.Future studies are required to establish if treatment with IVIG is of benefit in children with encephalitis of all causes.Such studies should take into account the challenges encountered and lessons learnt from the IgNiTE study.
December 2014.The trial was assigned an International Standard Randomised Controlled Trial Number on 24 June 2015 (ISRCTN 15791925), and a European Clinical Trials Database number (2014-002997-35).A Trial Steering Committee (TSC) was established to oversee the trial, and an independent Data Monitoring and Ethics Committee was set up to monitor the safety, efficacy and overall conduct of the study.

Table 1
Baseline characteristics of enrolled participants

Table 3
Secondary clinical outcomes

Table 5
Neuropsychology outcomes at 12 months after randomisation : green = normal neurodevelopmental score, yellow = mild impairment, red = severe impairment.*Young person unable to complete full battery due to attention or behavioural needs FSIQ, full-scale IQ; PRI, perceptual reasoning index; VCI, verbal comprehension index; VSI, visual spatial index; WMI, working memory index.