Multisystem inflammatory syndrome in children (MIS-C): A nationwide collaborative study in the Greek population

Multisystem inflammatory syndrome in children (MIS-C) is a rare but severe hyperinflammatory condition that may occur following SARS-CoV-2 infection. This retrospective, descriptive study of children hospitalized with multisystem inflammatory syndrome in children (MIS-C) in 12 tertiary care centers from 3/11/2020 to 12/31/2021. Demographics, clinical and laboratory characteristics, treatment and outcomes are described. Among 145 patients (95 males, median age 8.2 years) included, 123 met the WHO criteria for MIS-C, while 112 (77%) had serological evidence of SARS-CoV-2 infection. Fever was present in 99%, gastrointestinal symptoms in 77%, mucocutaneous involvement in 68% and respiratory symptoms in 28%. Fifty-five patients (38%) developed myocarditis, 29 (20%) pericarditis and 19 (13%) coronary aneurysms. Among the above cases 11/55 (20%), 1/29 (3.4%) and 5/19 (26.3%), respectively, cardiac complications had not fully resolved at discharge. Underlying comorbidities were reported in 18%. Median CRP value was 155 mg/l, ferritin 535 ng/ml, PCT 1.6 ng/ml and WBC 14.2 × 109/mm3. Most patients had elevated troponin (41.3%) and/or NT-pro-BNP (49.6%). Intravenous immunoglobulin plus corticosteroids were used in 117/145 (80.6%), monotherapy with IVIG alone in 13/145 (8.9%) and with corticosteroids alone in 2/145 (1.3%). Anti-IL1 treatment was added in 15 patients (10.3%). Thirty-three patients (23%) were admitted to the PICU, 14% developed shock and 1 required ECMO. Mortality rate was 0.68%. The incidence of MIS-C was estimated at 0.69/1000 SARS-CoV-2 infections. Patients who presented with shock had higher levels of NT-pro-BNP compared to those who did not (p < 0.001). Acute kidney injury and/or myocarditis were associated with higher risk of developing shock.

CONCLUSION

MIS-C is a novel, infrequent but serious disease entity. Cardiac manifestations included myocarditis and pericarditis, which resolved in most patients before discharge. Timely initiation of immunomodulatory therapy was shown to be effective. NT-pro-BNP levels may provide a better prediction and monitoring of the disease course. Further research is required to elucidate the pathogenesis, risk factors and optimal management, and long-term outcomes of this clinical entity.

WHAT IS KNOWN

• MIS-C is an infrequent but serious disease entity. • Patients with MIS-C present with multi-organ dysfunction, primarily involving the gastrointestinal and cardiovascular systems.

WHAT IS NEW

• NT-pro-BNP levels may provide a better prediction and monitoring of the disease course. • Acute kidney injury and/or myocarditis were associated with higher risk of developing shock.

Clinical phenotypes and outcomes in children with multisystem inflammatory syndrome across SARS-CoV-2 variant eras: a multinational study from the 4CE consortium

Background

Multisystem inflammatory syndrome in children (MIS-C) is a severe complication of SARS-CoV-2 infection. It remains unclear how MIS-C phenotypes vary across SARS-CoV-2 variants. We aimed to investigate clinical characteristics and outcomes of MIS-C across SARS-CoV-2 eras.

Methods

We performed a multicentre observational retrospective study including seven paediatric hospitals in four countries (France, Spain, U.K., and U.S.). All consecutive confirmed patients with MIS-C hospitalised between February 1st, 2020, and May 31st, 2022, were included. Electronic Health Records (EHR) data were used to calculate pooled risk differences (RD) and effect sizes (ES) at site level, using Alpha as reference. Meta-analysis was used to pool data across sites.

Findings

Of 598 patients with MIS-C (61% male, 39% female; mean age 9.7 years [SD 4.5]), 383 (64%) were admitted in the Alpha era, 111 (19%) in the Delta era, and 104 (17%) in the Omicron era. Compared with patients admitted in the Alpha era, those admitted in the Delta era were younger (ES -1.18 years [95% CI -2.05, -0.32]), had fewer respiratory symptoms (RD -0.15 [95% CI -0.33, -0.04]), less frequent non-cardiogenic shock or systemic inflammatory response syndrome (SIRS) (RD -0.35 [95% CI -0.64, -0.07]), lower lymphocyte count (ES -0.16 × 109/uL [95% CI -0.30, -0.01]), lower C-reactive protein (ES -28.5 mg/L [95% CI -46.3, -10.7]), and lower troponin (ES -0.14 ng/mL [95% CI -0.26, -0.03]). Patients admitted in the Omicron versus Alpha eras were younger (ES -1.6 years [95% CI -2.5, -0.8]), had less frequent SIRS (RD -0.18 [95% CI -0.30, -0.05]), lower lymphocyte count (ES -0.39 × 109/uL [95% CI -0.52, -0.25]), lower troponin (ES -0.16 ng/mL [95% CI -0.30, -0.01]) and less frequently received anticoagulation therapy (RD -0.19 [95% CI -0.37, -0.04]). Length of hospitalization was shorter in the Delta versus Alpha eras (-1.3 days [95% CI -2.3, -0.4]).

Interpretation

Our study suggested that MIS-C clinical phenotypes varied across SARS-CoV-2 eras, with patients in Delta and Omicron eras being younger and less sick. EHR data can be effectively leveraged to identify rare complications of pandemic diseases and their variation over time.

Funding

None.