A New Disease With Unknown Sequelae: Six-Month Multidisciplinary Follow-Up and Outcomes of Paediatric Inflammatory Multisystem Syndrome (PIMS-TS) Patients at a UK Tertiary Paediatric Centre

Background: Paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS), a new, rare post-infectious complication of SARS-CoV-2, was first defined by the Royal College of Paediatrics and Child Health in April 2020. The natural history of PIMS-TS is unknown.  Methods: Children (<18 years old) meeting diagnostic criteria for PIMS-TS were followed up by a multidisciplinary team of specialists at regular intervals over 6 months after their acute admission.  Findings: 46 children were identified. Median age at presentation was 10·2 years (IQR 8·8-13·3), 65·2% were male and 80·4% from ethnic minority groups. Systemic inflammation resolved in all. 90·5% (38/42) whom had positive SARS-CoV-2 IgG within six weeks of admission remained seropositive at six months. Echocardiograms were normal in 96% at six months. Gastrointestinal symptoms, although present in 95·7% at onset were minimal in follow-up (6·5%). Objective renal, haematology, and otolaryngology findings largely resolved by six months. Whilst minor abnormalities on neurological exam were identified in 52·2% and 39·1% at six weeks and six months respectively, we found no functional impairment by Expanded Disability Status Scale (six-month median score 0, IQR 0-1). Physiotherapy assessment revealed persisting poor exercise tolerance. Despite improvement in median manual muscle test-8 scores from 53/80 (IQR 43-64) during hospitalisation to 80/80 (IQR 68-80), 45% demonstrated six-minute walk test results <3 rd centile for age/sex at six months. Parental (19%) and self-report (22%) revealed severe emotional difficulties at six months. 31·1% of parents reported anxiety about possible PIMS-TS relapse in their child with 20% taking additional  isolation precautions and 22·2% were concerned about ongoing medical vulnerability. 97·8% patients were back in full-time education by six months.  Interpretation: Despite initial severe illness, by six months few organ-specific sequelae were observed. Ongoing concerns requiring physical re-conditioning and mental health support remained. Longer-term follow-up will help define the extended natural history of PIMS-TS. Funding Statement: None to declare. Declaration of Interests: AB declares consultancy work for Gilead Inc. within the past three years of which the role did not impact on the writing of this manuscript. The remainder of authors have no declarations of interest to declare. Ethics Approval Statement: As the data analysis was retrospective and no additional data were collected beyond those required for standard medical care, a full ethics review under the terms of the Governance Arrangements of Research Ethics Committees in the UK was not required. A clinical audit was registered with GOSH NHS Foundation Trust Audit Committee (#2857).