Abstract

Objective

To characterize the clinical-epidemiological profile of multisystem inflammatory syndrome in children temporally associated with COVID-19 (MIS-C), and to identify factors associated with MIS-C deaths in Brazil, 2020.

Methods

This was a cross-sectional study, using national MIS-C monitoring data. Logistical regression was performed to estimate crude and adjusted odds ratios (OR).

Results

Median case (n=652) age was 5 years, 57.1% were male, 52.0% were of brown race/skin color and 6.4% died. Likelihood of death was greater among those who presented O2 saturation <95% (ORa=4.35 – 95%CI 1.69;11.20) and altered urea results (ORa=5.18 – 95%CI 1.91;14.04); likelihood of death was lower when red skin blotches were not present (ORa=0.23 – 95%CI 0.09;0.62), when anticoagulants were used (ORa=0.32 – 95%CI 0.12;0.89) and when immunoglobulins were used (ORa=0.38 – 95%CI 0.15;1.01).

Conclusion

Fatality ratios were higher among cases that presented O2 saturation <95% and altered urea results. Fatality ratios were lower among those with red skin blotches, and those who used immunoglobulins and anticoagulants.

Coronavirus Infections; Pediatrics; Systemic Inflammatory Response Syndrome; Death; Epidemiological Monitoring; Cross-Sectional Studies

Introduction

At the beginning of the COVID-19 pandemic, caused by the SARS-CoV-2 coronavirus, it was consensus that children had mild symptoms and that most of them were asymptomatic and not included in the conditions and risk factors for COVID-19 complications.¹1. She J, Liu L, Liu W. COVID-19 epidemic: disease characteristics in children. J Med Virol. 2020 Jul;92(7):747-54. doi: https://doi.org/10.1002/jmv.25807.
https://doi.org/10.1002/jmv.25807... Early studies on COVID-19 also reported low incidence and low fatality ratios among children and adolescents.¹1. She J, Liu L, Liu W. COVID-19 epidemic: disease characteristics in children. J Med Virol. 2020 Jul;92(7):747-54. doi: https://doi.org/10.1002/jmv.25807.
https://doi.org/10.1002/jmv.25807...

In April 2020, during the peak of the pandemic in Europe, an increase in the hospitalization of children/adolescents with severe multisystemic inflammation similar to Kawasaki syndrome, possibly associated with prior SARS-CoV-2 infection, was identified.³3. Riphagen S, Gomez X, Gonzalez-Martinez C, Wilkinson N, Theocharis P. Hyperinflammatory shock in children during COVID-19 pandemic. Lancet. 2020 May 23;395(10237):1607-8. doi: https://doi.org/10.1016/S0140-6736(20)31094-1.
https://doi.org/10.1016/S0140-6736(20)31... Following an alert issued by the United Kingdom, several countries recorded an increase in similar cases,²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749... later called multisystem inflammatory syndrome in children (MIS-C).⁶6. World Health Organization. Case Report Form for suspected cases of multisystem inflammatory syndrome (MIS) in children and adolescents temporally related to COVID-19 [Internet]. Geneva: WHO. 2020 Jun 01 [acesso 23 ago. 2021]. Disponível em: https://www.who.int/publications/i/item/WHO-2019-nCoV-MIS_Children_CRF-2020.2
https://www.who.int/publications/i/item/...

Although rare, the syndrome has drawn attention worldwide. It is a condition characterized by high and persistent fever, with a spectrum of signs and symptoms affecting several systems (gastrointestinal, dermatocutaneous, and circulatory manifestations, among others).²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749... Respiratory symptoms are not always present, but there is a significant increase in inflammatory markers and the clinical picture can evolve to shock and coagulopathy.²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749...

In Brazil, systematic monitoring of MIS-C was implemented on July 24, 2020 by the Health Surveillance Secretariat of the Ministry of Health, throughout the national territory, allowing retroactive notification of cases identified prior to its implementation.⁷7. Ministério da Saúde (BR). Nota técnica n. 16/2020 CGPNI/ DEIDT/SVS/MS: orientações sobre a notificação da síndrome inflamatória multissistêmica (SIM-P) temporalmente associada à COVID-19. [Brasília, DF: MS]; 2020 [acesso 23 ago. 2021]. Disponível em https://portaldeboaspraticas.iff.fiocruz.br/biblioteca/nota-tecnica-no-16-2020-cgpni-deidt-svs-ms.
https://portaldeboaspraticas.iff.fiocruz... The objectives of this study were to characterize the clinical-epidemiological profile of MIS-C cases and to identify factors associated with deaths caused by MIS-C in Brazil in 2020.

Methods

A cross-sectional study was conducted, based on notified suspected cases of MIS-C in Brazil, taking the date of symptom onset between February 26, 2020 (date of confirmation of the first COVID-19 case in the country) and December 31, 2020.

Duplicate notifications were excluded by the deterministic method, comparing name and date of birth, mother's name, and Federative Unit of residence. The records were then classified according to the definition adopted by the Ministry of Health,⁷7. Ministério da Saúde (BR). Nota técnica n. 16/2020 CGPNI/ DEIDT/SVS/MS: orientações sobre a notificação da síndrome inflamatória multissistêmica (SIM-P) temporalmente associada à COVID-19. [Brasília, DF: MS]; 2020 [acesso 23 ago. 2021]. Disponível em https://portaldeboaspraticas.iff.fiocruz.br/biblioteca/nota-tecnica-no-16-2020-cgpni-deidt-svs-ms.
https://portaldeboaspraticas.iff.fiocruz... taking a ‘confirmed case’ to be an individual under 20 years old, hospitalized, and with presence of:

1. a) High (minimum: 38ºC) and persistent fever (for 3 or more days).

2. b) Evidence of COVID-19 (molecular biology, positive antigenic test or serology) or history of contact with people with COVID-19.

3. c) Elevated inflammatory markers, such as altered laboratory results for erythrocyte sedimentation rate (ESR), C-reactive protein or procalcitonin, among others.

4. d) At least two of the following signs/symptoms:

5. – Non-purulent conjunctivitis or bilateral skin rash or signs of mucocutaneous inflammation (oral, on hands or feet).

6. – Arterial hypotension or shock.

7. – Manifestations of myocardial dysfunction, pericarditis, valvulitis, or coronary artery abnormalities, including echocardiogram findings or troponin elevation or N-terminal pro-B-type natriuretic peptide (NT-proBNP).

8. – Evidence of coagulopathy by thrombin time (TT), activated partial thromboplastin time (aPTT) or elevated D-dimer levels.

9. – Acute gastrointestinal manifestations (diarrhea, vomiting or abdominal pain).

10. e) After ruling out any other causes of obvious infectious origin of inflammation, including bacterial sepsis, staphylococcal or streptococcal shock syndrome.

The MIS-C case epidemic curve was compared to the COVID-19 curve for individuals under 20 years of age in Brazil, considering the moving average of the last three epidemiological weeks (EW) of symptom onset. Cases of severe acute respiratory syndrome (SARS) and flu-like syndrome confirmed as COVID-19 cases by laboratory, clinical, clinical-epidemiological, or clinical-imaging criteria were included.

MIS-C cases and crude incidence rates were presented according to Federative Unit of residence. Incidence was calculated by dividing the number of confirmed cases by the number of people under 20 years old, multiplied by 100,000. We also calculated the case fatality ratio of SIM-P in Brazil by dividing the number of deaths, by the number of total cases, multiplied by 100.

The MIS-C data were taken from the national monitoring database [online notification on the REDCap^®platform, hosted and under the domain of the Brazilian National Health System Information Technology Department (DATASUS)]. With regard to COVID-19 cases, data on SARS were taken from the Influenza Epidemiological Surveillance Information System, while data on flu-like syndrome were taken from the e-SUS Notifica system, both of which are available on the OpenDATASUS platform.⁹9. Ministério da Saúde (BR), Banco de dados do Sistema Único de Saúde. Notificações de Síndrome Gripal, sistema e-SUS VE notifica. [Rio de Janeiro]: MS; [s.d.; acesso 4 fev. 2021]. Disponível em: https://opendatasus.saude.gov.br/
https://opendatasus.saude.gov.br/... Brazilian Institute of Geography and Statistics (IBGE) population projections for the year 2020 were used to calculate incidence.¹⁰10. Ministério da Saúde (BR), Banco de dados do Sistema Único de Saúde. Projeção da população das unidades da federação por sexo e grupos de idade: 2000-2030: notas técnicas. [Rio de Janeiro]: MS; [s.d.; acesso 4 fev. 2021]. Disponível em: http://tabnet.datasus.gov.br/cgi/Ibge/projpopuf.pdf
http://tabnet.datasus.gov.br/cgi/Ibge/pr... All the data used were retrieved on February 4, 2021, considering notifications as at January 14, 2021.

Characterization of MIS-C cases included simple and relative frequencies, and measures of central tendency of the following independent variables:

1. a) Sociodemographic variables: age (in years: under 1; 1-9; under 20); sex (female; male); race/skin color (white; black; brown; indigenous; yellow).

2. b) Prior presence of comorbidities (yes; no).

3. c) Signs/symptoms presented in large and detailed groups (yes; no):

4. – Gastrointestinal – abdominal pain, nausea or vomiting, diarrhea;

5. – Dermatocutaneous – conjunctivitis, red blotches on body (such as rash and exanthema);

6. – Respiratory – dyspnea, O₂saturation <95%, cough, runny nose, sore throat;

7. – Neurological – headache, lethargy, irritability, mental confusion;

8. – Circulatory and hemodynamic – tachycardia, hypotension/shock, skin color alterations (such as paleness and cyanosis);

9. – Edema – hand or foot edema, lymphadenopathy;

10. – Myalgia;

11. – Oliguria.

12. d) Altered results for inflammation markers, coagulopathy or organ dysfunction (yes; no) – C-reactive protein, D-dimer, erythrocyte sedimentation rate (ESR), ferritin, lactate dehydrogenase, albumin, aspartate transaminase (AST), alanine transaminase (ALT), thrombin time, troponin, activated partial thromboplastin time, urea, creatinine, sodium, potassium.

13. e) Use in treatment (yes; no) – immunoglobulin, corticoid, anticoagulant, antiviral therapy.

14. f) COVID-19 confirmation criterion – laboratory evidence of SARS-CoV-2 infection (serology; molecular) or clinical-epidemiological criterion (temporally associated with a laboratory confirmed COVID-19 case in the last 30 days).

15. g) Occurrence of complications (yes; no).

16. h) Hospitalization in intensive care unit (ICU) (yes; no).

17. i) Time (in days: between symptom onset and hospitalization; length of inpatient stay; time spent in ICU).

18. j) Case progression (death; hospital discharge).

When analyzing factors associated with death, the dependent variable analyzed was case progression: MIS-C cases having 'death' as the outcome were compared to those having 'hospital discharge' as the outcome; records not showing progression were discarded.

A hierarchical theoretical model¹¹11. Victora CG, Huttly SR, Fuchs SC, Olinto MT. The role of conceptual frameworks in epidemiological analysis: a hierarchical approach. Int J Epidemiol. 1997;26(1):224-7. doi: https://doi.org/10.1093/ije/26.1.224.
https://doi.org/10.1093/ije/26.1.224... was built in order to process the independent variables, using the first five blocks of variables described above. First, simple logistic regression models were used to study the relationships between the independent variables and death, using variables that had at least 90% completeness in both comparison groups (death and hospital discharge).

Following this, the hierarchical approach to data modeling was adopted,¹¹11. Victora CG, Huttly SR, Fuchs SC, Olinto MT. The role of conceptual frameworks in epidemiological analysis: a hierarchical approach. Int J Epidemiol. 1997;26(1):224-7. doi: https://doi.org/10.1093/ije/26.1.224.
https://doi.org/10.1093/ije/26.1.224... using a multiple logistic regression model with variables that had a significance level of up to 10% (p-value<0.10) in the simple regression. The distal block was comprised of sociodemographic variables and prior presence of comorbidities (Model 1); on the intermediate levels, Model 2 included presence of signs and symptoms and Model 3, included altered results for markers of inflammatory activity, coagulopathy or organ dysfunction, while the proximal level included treatment (Model 4).

Inclusion of independent variables in the hierarchical multiple regression model was carried out in an ordered and sequential manner, moving in the distal-proximal direction (Models 1 to 4). At each level, variables that had a significance level of up to 5% (p-value<0.05) were kept in the model, so that all levels were adjusted by the variables from the same level and the previous levels. Association between death and the independent variables studied was expressed as crude odds ratios (ORc) and adjusted odds ratios (ORa) and their respective 95% confidence intervals (95%CI).

We opted to include specific sign/symptom variables in the regression models, rather than organizing them into large groups, since high or absolute frequency of the large groups was found among MIS-C cases that progressed to death, so that it was not possible to establish a comparison group. Multicollinearity diagnosis was also performed between specific sign/symptom variables identified in the simple regression, through the correlation matrix; for multiple regression, one specific sign/symptom variable was selected for each pair of variables that demonstrated a correlation coefficient ≥0.4 (moderate to high correlation).

MIS-C case records with missing data in any selected independent variable were considered to be losses for the multiple regression model. Taking the sample of cases included in the model, an odds ratio equal to 2.0, and a 10% difference in the outcome distribution between groups with or without the variable of interest, minimum power was estimated at 64.2%.

R 4.0.0 software was used for duplicate cleaning, data treatment and analysis, while Microsoft/Excel and QGIS3.¹²12. Feldstein LR, Rose EB, Horwitz SM, Collins JP, Newhams MM, Son MBF, et al. Multisystem inflammatory syndrome in U.S. children and adolescents. N Engl J Med. 2020 Jul 23;383(4):334-46. doi: https://doi.org/10.1056/NEJMoa2021680.
https://doi.org/10.1056/NEJMoa2021680... software were employed for data visualization.

The study design was submitted to the National Research Ethics Committee/National Health Council and approved on January 14, 2021 [Certificate of Submission for Ethical Appraisal No. 40867220.5.0000.0008].

Results

Brazil recorded 1,082 notifications of suspected MIS-C cases in 2020. Forty-three (4.0%) were duplicate records and 387 (35.8%) did not meet the case definition criteria, leaving 652 (60.2%) cases classified as confirmed MIS-C cases. Of these, 525 (80.6%) were discharged from hospital and 42 (6.4%) died. There were 85 (13.0%) records with no information on case progression on the notification form ( Figure 1 ).

The behavior of the MIS-C epidemic curve in Brazil was similar to that of the COVID-19 curve in children under 20 years of age; however, the curves showed differences in their temporal distributions. The peak in the moving average of MIS-C cases occurrence occurred five weeks after the COVID-19 peak in the pediatric age group (EW 30). The highest number of MIS-C case deaths (n=5) was recorded in EW 42 ( Figure 2 ).

The Federative Units of São Paulo (n=142; 21.8%), Federal District (n=58; 8.9%), Minas Gerais (n=57; 8.7%), Bahia (n=50; 7.7%) and Pará (n=50; 7.7%) accounted for more than 50% of the country’s MIS-C cases (Supplementary Material 1). MIS-C incidence in Brazil was 1.1 case per 100,000 population under 20 years of age. The states of Alagoas (2.2), Rio Grande do Norte (1.6), Pará (1.6), Ceará (1.2), São Paulo (1.2), Santa Catarina (1.2) and the Federal District (6.7) had incidences rates above the national average (Supplementary Material 1).

Table 1 presents the profile of the MIS-C cases: 64.3% of the children/adolescents were between 1 and 9 years old (median: 5 years), 57.1% were male, 52.0% were of brown race/skin color and approximately 80% had no comorbidities prior to MIS-C. Presence of some signs/symptoms of the gastrointestinal group was recorded in 87.6% of MIS-C cases, followed by dermatocutaneous signs/symptoms in 72.4% and respiratory signs/symptoms in 66.0%. As a mandatory case definition criterion, high and persistent fever was present in all cases.

A high frequency of altered results for markers of inflammation, coagulopathy, and organ dysfunction was found among MIS-C cases, with altered C-reactive protein, D-dimer and ESR standing out in more than 80% of cases (excluding tests not performed/unknown). Use of immunoglobulins and anticoagulants was recorded in 67.9% and 55.7% of MIS-C cases, respectively. Most children/adolescents were laboratory confirmed as having COVID-19 (78.4%), and 61.2% had serology results ( Table 1 ).

Median time elapsed between onset of signs/symptoms and hospitalization was 4 days, and median length of inpatient stay was 9 days. ICU hospitalization occurred in 44.5% of cases, with a median length of stay of six days (excluding cases with unknown information). The 42 cases of MIS-C that died were distributed over 15 Federative Units, among which Pará and São Paulo recorded the highest absolute number: 7 cases each.

Table 2 presents the characteristics of the MIS-C cases analyzed according to progression (death/hospital discharge) in crude regression. The <1 and <20 year-old age groups and presence of comorbidity prior to MIS-C were significantly associated with death. Regarding the clinical characteristics of deaths, we found a higher frequency of dyspnea, O₂saturation <95%, tachycardia, hypotension/shock, skin color alterations (such as paleness and cyanosis) and oliguria, and a lower frequency of conjunctivitis, red blotches on body (such as rash and exanthema), hand or foot edema and lymphadenopathy, in relation to those who were discharged from hospital.

We also found a higher frequency of altered AST, urea and creatinine results among MIS-C cases that died, when compared to those that were discharged from hospital. Use of immunoglobulins and anticoagulants was significantly associated with lower fatality, while the use of corticosteroids and antiviral therapy, was significantly associated with higher fatality. Supplementary Material 2 presents the analysis of P-PSI cases, according to additional characteristics.

Table 3 shows the results of multiple regression in hierarchical modeling, which included 28 MIS-cases that died and 368 cases that were discharged from hospital (70% of the 567 cases with known progression). Losses occurred due to missing data in the variables studied.

No statistically significant association was found between the adjusted variables in Model 1 and the outcome 'death'. In Model 2, we found that the likelihood of O₂saturation<95% was significantly higher (ORa=4.35 - 95%CI 1.69;11.20) and the presence of red blotches on the body (ORa=0.23 - 95%CI 0.09;0.62) was significantly lower among those who died, when compared to those who were discharged from hospital. The 'conjunctivitis', 'dyspnea', 'tachycardia' and 'hypotension/shock' variables were not included in the hierarchical model due to identification of moderate correlation with the 'red blotches on body' variable (for conjunctivitis) and the 'O2 saturation <95%' variable (for the remainder) (Supplementary Material 3).

In Model 3, which was controlled by the variables with association in the previous models, only altered urea test results showed statistically significant association with death (ORa=5.18 - 95%CI 1.91;14.04). In Model 4, after including the treatment-related variables, use of anticoagulants was associated with a significantly lower likelihood of death (ORa=0.32 - 95%CI 0.12;0.89), while the significance effect of immunoglobulin use in reducing the likelihood of death was borderline (ORa=0.38 - 95%CI 0.15;1.01).

Discussion

MIS-C cases in Brazil in 2020 had a median age of 5 years and most occurred in children/adolescents of brown race/skin color and of the male sex, after the COVID-19 peak in the pediatric age group. Clinical manifestations were diverse and were mostly associated with elevated markers of inflammation, coagulopathy or organ dysfunction, and positive serology for SARS-CoV-2. The MIS-C fatality ratio in Brazil was 6.4% in 2020, with O₂saturation <95% and altered urea results being factors associated with death. Fatality was lower among cases with no red blotches on the body and those who used anticoagulants and immunoglobulins.

Occurrence of MIS-C after the COVID-19 peak in the pediatric age group has been seen in other countries, most of which reported a 3- to 5-week difference between the curves.²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749... Also consistent with the literature were the results of the frequency of SARS-CoV-2 serology test positivity and presence of inflammatory markers/coagulopathy (also described in severe COVID-19 cases).⁴4. Godfred-Cato S, Bryant B, Leung J, Oster ME, Conklin L, Abrams J, et al. COVID-19 associated multisystem inflammatory syndrome in children: United States, March-July 2020. MMWR Morb Mortal Wkly Rep. 2020 Aug 14;69(32):1074-80. doi: https://doi.org/10.15585/mmwr.mm6932e2.
https://doi.org/10.15585/mmwr.mm6932e2... These aspects support the hypothesis that MIS-C is a late immune response to SARS-CoV-2 infection in children/adolescents.¹⁵15. Felsenstein S, Willis E, Lythgoe H, McCann L, Cleary A, Mahmood K, et al. Presentation, treatment response and short-term outcomes in paediatric multisystem inflammatory syndrome temporally associated with SARS-CoV-2 (PIMS-TS). J Clin Med. 2020 Oct 14;9(10):3293. doi: https://doi.org/10.3390/jcm9103293.
https://doi.org/10.3390/jcm9103293...

The median age of MIS-C cases in Brazil was lower than that found in most studies,²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749... and was closer to that found for Kawasaki Syndrome or acute pediatric COVID-19.¹⁸18. Feldstein LR, Tenforde MW, Friedman KG, Newhams M, Rose EB, Dapul H, et al. Characteristics and outcomes of US children and adolescents with multisystem inflammatory syndrome in children (MIS-C) compared with severe acute COVID-19. JAMA. 2021 Mar 16;325(11):1074-87. doi: https://doi.org/10.1001/jama.2021.2091.
https://doi.org/10.1001/jama.2021.2091... This result may indicate that health services in Brazil were more sensitive in suspecting MIS-C in younger children/adolescents, or that the study included cases of other inflammatory manifestations similar to MIS-C. The overlap with other multisystemic syndromes has been described in several papers.²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749... The high frequency of children under 1 year of age also drew attention, especially among those who died, this being precisely an age group that presents an even greater challenge for diagnosis.¹⁶16. Guimarães D, Pissarra R, Reis-Melo A, Guimarães H. Multisystem inflammatory syndrome in children (MISC): a systematic review. Int J Clin Pract. 2021 Jun 9:e14450. doi: https://doi.org/10.1111/ijcp.14450.
https://doi.org/10.1111/ijcp.14450...

The frequency rates of MIS-C cases in those of brown race/skin color and of the male sex were consistent with the literature;²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749... however, the contribution of genetic factors remains poorly elucidated and it is believed that the results may be related to environmental factors such as social and racial inequities.¹⁶16. Guimarães D, Pissarra R, Reis-Melo A, Guimarães H. Multisystem inflammatory syndrome in children (MISC): a systematic review. Int J Clin Pract. 2021 Jun 9:e14450. doi: https://doi.org/10.1111/ijcp.14450.
https://doi.org/10.1111/ijcp.14450... It is noteworthy that race/skin color was not recorded in more than 20% of the MIS-C cases, even though including this information is mandatory for health information systems in Brazil.²²22. Ministério da Saúde (BR). Portaria de consolidação n. 1, de 28 de setembro de 2017. Consolidação das normas sobre os direitos e deveres dos usuários da saúde, a organização e o funcionamento do Sistema Único de Saúde. [Brasília, DF]: MS; atualizado 28 set. 2017; acesso 23 ago. 2021]. Disponível em: http://bvsms.saude.gov.br/bvs/saudelegis/gm/2017/prc0001_03_10_2017.html
http://bvsms.saude.gov.br/bvs/saudelegis...

The study found clinical diversity and multiple organ involvement among MIS-C cases, with important differences between those who died and those who were discharged from hospital, corroborating the current understanding of the scientific community about the existence of different phenotypes and levels of severity of the syndrome.²2. Kabeerdoss J, Pilania RK, Karkhele R, Kumar TS, Danda D, Singh S. Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management. Rheumatol Int. 2021;41(1):19-32. doi: https://doi.org/10.1007/s00296-020-04749-4.
https://doi.org/10.1007/s00296-020-04749... High fatality among MIS-C cases in the presence of respiratory signs/symptoms and absence of dermatocutaneous manifestations, for example, has been described previously.⁴4. Godfred-Cato S, Bryant B, Leung J, Oster ME, Conklin L, Abrams J, et al. COVID-19 associated multisystem inflammatory syndrome in children: United States, March-July 2020. MMWR Morb Mortal Wkly Rep. 2020 Aug 14;69(32):1074-80. doi: https://doi.org/10.15585/mmwr.mm6932e2.
https://doi.org/10.15585/mmwr.mm6932e2... Children/adolescents with mucocutaneous lesions, however, may be at increased risk for coronary abnormalities, especially among those manifesting typical or atypical Kawasaki Syndrome characteristics.²³23. Zhu F, Ang JY. 2021 update on the clinical management and diagnosis of kawasaki disease. Curr Infect Dis Rep. 2021;23(3):3. doi: https://doi.org/10.1007/s11908-021-00746-1.
https://doi.org/10.1007/s11908-021-00746...

Altered urea and creatinine tests and elevated presence of oliguria among the MIS-C cases that died indicate that kidney failure seems to play an important role in the clinical course of severe cases. Diagnosis of MIS-C has been previously associated with children/adolescents hospitalized for COVID-19 who presented acute kidney injury.¹⁶16. Guimarães D, Pissarra R, Reis-Melo A, Guimarães H. Multisystem inflammatory syndrome in children (MISC): a systematic review. Int J Clin Pract. 2021 Jun 9:e14450. doi: https://doi.org/10.1111/ijcp.14450.
https://doi.org/10.1111/ijcp.14450... Urea alteration is also predictive of pneumonia severity, especially in the presence of sepsis, and can result from the administration of drugs such as corticosteroids, as well as from multiple organ involvement resulting from multisystem inflammation.²⁵25. Sood M, Sharma S, Sood I, Sharma K, Kaushik A. Emerging evidence on multisystem inflammatory syndrome in children associated with SARS-CoV-2 Infection: a systematic review with meta-analysis. SN Compr Clin Med. 2021 Jan 7:1-10. doi: https://doi.org/10.1007/s42399-020-00690-6. Epub ahead of print.
https://doi.org/10.1007/s42399-020-00690...

The respiratory and renal impairments found in this study may be related to a combination of hypovolemic and hyperinflammatory shock. Although the pathophysiology of MIS-C has not been completely elucidated, multiple organ failure is believed to occur due to the exacerbated delayed immune response, and not necessarily to the direct action of the virus on tissues.⁵5. Tang Y, Li W, Baskota M, Zhou Q, Fu Z, Luo Z, et al. Multisystem inflammatory syndrome in children during the coronavirus disease 2019 (COVID-19) pandemic: a systematic review of published case studies. Transl Pediatr. 2021 Jan;10(1):121-35. doi: https://doi.org/10.21037/tp-20-188.
https://doi.org/10.21037/tp-20-188...

Circulatory/hemodynamic system complications have been shown to be more frequent in MIS-C than in Kawasaki Syndrome and, although there is a risk of sequelae, good prognosis has been observed.¹⁸18. Feldstein LR, Tenforde MW, Friedman KG, Newhams M, Rose EB, Dapul H, et al. Characteristics and outcomes of US children and adolescents with multisystem inflammatory syndrome in children (MIS-C) compared with severe acute COVID-19. JAMA. 2021 Mar 16;325(11):1074-87. doi: https://doi.org/10.1001/jama.2021.2091.
https://doi.org/10.1001/jama.2021.2091... These complications have also been observed in severe and fatal outcomes of COVID-19 in adults, and may be associated with myocardial impairment due to the phenomenon known as 'cytokine storm', as well as progression of acute respiratory failure.¹⁸18. Feldstein LR, Tenforde MW, Friedman KG, Newhams M, Rose EB, Dapul H, et al. Characteristics and outcomes of US children and adolescents with multisystem inflammatory syndrome in children (MIS-C) compared with severe acute COVID-19. JAMA. 2021 Mar 16;325(11):1074-87. doi: https://doi.org/10.1001/jama.2021.2091.
https://doi.org/10.1001/jama.2021.2091... Alterations in biomarkers of cardiac function and hyperinflammatory reaction have been reported as predictors of MIS-C severity, but were not included in the study of association with death due to lack of data.¹⁸18. Feldstein LR, Tenforde MW, Friedman KG, Newhams M, Rose EB, Dapul H, et al. Characteristics and outcomes of US children and adolescents with multisystem inflammatory syndrome in children (MIS-C) compared with severe acute COVID-19. JAMA. 2021 Mar 16;325(11):1074-87. doi: https://doi.org/10.1001/jama.2021.2091.
https://doi.org/10.1001/jama.2021.2091...

In Brazil, the therapy used in cases of MIS-C was varied, which may be related to nonspecific pathophysiological manifestations, the absence of a clear prognosis, and the possibility of putting life at risk.¹⁵15. Felsenstein S, Willis E, Lythgoe H, McCann L, Cleary A, Mahmood K, et al. Presentation, treatment response and short-term outcomes in paediatric multisystem inflammatory syndrome temporally associated with SARS-CoV-2 (PIMS-TS). J Clin Med. 2020 Oct 14;9(10):3293. doi: https://doi.org/10.3390/jcm9103293.
https://doi.org/10.3390/jcm9103293... However, there is no standardized treatment for MIS-C in the literature;⁵5. Tang Y, Li W, Baskota M, Zhou Q, Fu Z, Luo Z, et al. Multisystem inflammatory syndrome in children during the coronavirus disease 2019 (COVID-19) pandemic: a systematic review of published case studies. Transl Pediatr. 2021 Jan;10(1):121-35. doi: https://doi.org/10.21037/tp-20-188.
https://doi.org/10.21037/tp-20-188... treatment protocols have been proposed, based on clinical management guides for other inflammatory syndromes with a similar clinical spectrum.⁵5. Tang Y, Li W, Baskota M, Zhou Q, Fu Z, Luo Z, et al. Multisystem inflammatory syndrome in children during the coronavirus disease 2019 (COVID-19) pandemic: a systematic review of published case studies. Transl Pediatr. 2021 Jan;10(1):121-35. doi: https://doi.org/10.21037/tp-20-188.
https://doi.org/10.21037/tp-20-188... Use of immunoglobulin is usually the first choice of treatment,¹⁷17. Zou H, Lu J, Liu J, Wong JH-W, Cheng S, Li Q, et al. Characteristics of pediatric multi-system inflammatory syndrome (PMIS) associated with COVID-19: a meta-analysis and insights into pathogenesis. Int J Infect Dis. 2021;102:319-26. doi: https://doi.org/10.1016/j.ijid.2020.11.145.
https://doi.org/10.1016/j.ijid.2020.11.1... combined or not with use of corticoids in moderate and severe cases; use of anticoagulants is indicated in cases of thromboembolic events, and plays an important role in preventing shock.⁵5. Tang Y, Li W, Baskota M, Zhou Q, Fu Z, Luo Z, et al. Multisystem inflammatory syndrome in children during the coronavirus disease 2019 (COVID-19) pandemic: a systematic review of published case studies. Transl Pediatr. 2021 Jan;10(1):121-35. doi: https://doi.org/10.21037/tp-20-188.
https://doi.org/10.21037/tp-20-188... The results found suggest that immunoglobulins and anticoagulants may have been protective factors against a fatal outcome; the results, however, should not be viewed as measures of efficacy, given the observational nature of the study.

MIS-C fatality in Brazil was high when compared to case series published by other countries (approximately 1 to 2%),⁴4. Godfred-Cato S, Bryant B, Leung J, Oster ME, Conklin L, Abrams J, et al. COVID-19 associated multisystem inflammatory syndrome in children: United States, March-July 2020. MMWR Morb Mortal Wkly Rep. 2020 Aug 14;69(32):1074-80. doi: https://doi.org/10.15585/mmwr.mm6932e2.
https://doi.org/10.15585/mmwr.mm6932e2... and this may reflect differences in the dynamics of transmission, the epidemiological situation, availability of diagnostic resources, care provided by local health services, as well as underreporting of milder cases.

This study has other limitations related to the quality of the records, such as incompleteness and non-standardization. These limitations may have implications for the classification of confirmed cases, based on the variables filled out on the notification form. Regarding this aspect, it is noteworthy that all MIS-C case definition conditions were mandatorily recorded among the cases classified as confirmed; however, it was not always possible to obtain detailed data on subsequent variables, such as differential etiologic diagnoses having been carried out. The clinical-epidemiological profile presented and the selection of variables for the study of association with death may also have been influenced by under-recording or absence of variables in the database, such as race/skin color, inflammatory and cardiac function markers, and other classes of drugs.

It is also noteworthy that the losses in the hierarchical regression model occurred due to under-recording of laboratory results and treatment, which may be a consequence of differentiated access to diagnostic and therapeutic resources. Moreover, the quantitative results of laboratory markers are not available in the notification records, making it impossible to know at what stage of the syndrome the altered qualitative result was obtained. The temporality of the clinical characteristics and drug administration has not been established either. For these reasons, interpretation and comparison of the findings of factors associated with death should be viewed in an exploratory manner, also considering the possibility of residual confounding.

On the other hand, this study presents the largest MIS-C case series described in Brazil and was the first conducted based on the national monitoring database. Future studies on representativeness and data quality can qualify the interpretation of the results presented. Additional investigations that establish the temporal relationship between clinical manifestations, details of laboratory results, and treatment administered are also necessary for better clinical-epidemiological definition and definition of factors associated with death.

This study also contributes to the understanding of the signs of MIS-C severity, in the face of which specialized care is recommended, with the joint participation of multidisciplinary teams, timely treatment, monitoring of renal function and follow-up of children/adolescents to detect possible sequelae, especially in relation to cardiac involvement, whenever possible.²⁴24. Abrams JY, Oster ME, Godfred-Cato SE, Bryant B, Datta SD, Campbell AP, et al. Factors linked to severe outcomes in multisystem inflammatory syndrome in children (MIS-C) in the USA: a retrospective surveillance study. Lancet Child Adolesc Health. 2021;5(5):323-31. doi: https://doi.org/10.1016/S2352-4642(21)00050-X.
https://doi.org/10.1016/S2352-4642(21)00... We also highlight the importance of SUS care and epidemiological surveillance health workers being aware and able to recognize, notify and investigate different spectrums of clinical manifestations of MIS-C, in order to improve the understanding of the syndrome, favoring timely treatment and better prognosis for children and adolescents affected by COVID-19.

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