Modulation format comparison in PMD-Impaired 40Gbps systems

Tese de mestrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Störungsanalyse und -minderung für kosteneffiziente OFDM-basierte Zugangssysteme

The growth in broadband connection speed has been exponential, and this trend will continue in the foreseeable future [1]. An access network is a connection between users and service providers and therefore a key element in support of this growth. While expanding its broadband offer a service provider must ensure seamless migration through compatibility with legacy networks, and also create an offer that is attractive to customers. Access networks are designed to support numerous users at different distances from the service provider. Cost-efficiency is mandatory. It usually relies upon using Passive Optical Networks (PONs) and low complexity electro-optical devices (direct modulation/detection), whose performance can be unlocked by digital signal processing to mitigate components’ limitations. Novel optical modulation formats help to achieve large spectral efficiencies and allow advanced signal distribution. One such modulation format is Orthogonal Frequency Division Multiplexing (OFDM), which offers a compact spectrum, resilience to chromatic dispersion and flexible subcarrier allocation [2]. Legacy PON systems use C-band (1500nm) downlinks and O-band (1330nm) uplinks [3]–[9]. The C-band has low attenuation at the cost of higher chromatic dispersion [10]. The O-band has practically no chromatic dispersion but higher attenuation [10] enabling the use of simpler transmitters, Directly Modulated Lasers (DMLs) for example. The latest PON systems must enable parallel operation with legacy systems. For this reason they operate both in the C-band down- and uplink [11]. A DML has chirp as a by-product of transmission [12], [13]. Chirp interacts with fibre chromatic dispersion (C-band) to create Subcarrier-to-Subcarrier Intermixing Interference (SSII) at the receiver after direct detection [14]. This occurs despite OFDM’s resilience to chromatic dispersion and is one of the main impairments of cost-effective OFDM-based access systems. The main contribution of this work is to predict and analyse the impact of SSII as an impairment and to propose and experimentally verify mitigation techniques. An analytical formulation capable of Signal-to-Noise Ratio (SNR) prediction for OFDM-based DML transmission is derived. This formulation is capable of determining the contribution of each subcarrier to SNR degradation. The DML intensity and frequency responses are included in the formulation by a, also presented, simplified laser model. The predictions of this formulation are experimentally validated under various conditions [15]. A bit-and-power loading algorithm is also proposed. It adapts the power and capacity of each subcarrier to the channel in order to maximize total transmission capacity [16]. Finally, an adaptive equalizer is presented. An optimization procedure is proposed to enable efficient mitigation of SSII [17]. Experimental results show a capacity increase of ≃33% when using the proposed optimized equalizer [18].Der Bedarf an hochbitratigen Telekommunikationsverbindungen zeigt seit jeher ein exponentielles Wachstum, welches auch in näher Zukunft anhält [1]. Die Zugangsnetze bilden die Verbindungen zwischen Endnutzern und Telekommunikationsanbietern und leisten damit einen wesentlichen Beitrag zur Realisierung des Wachstums. Um das Breitbandangebot zu erweitern, müssen Telekommunikationsanbieter die rückwärtskompatible Aufrüstung existierender Netzwerke gewährleisten und dabei ebenso ein attraktives Kundenangebot schaffen. Zugangsnetze werden entworfen, um eine Vielzahl an Kunden in unterschiedlichen Entfernungen vom Telekommunikationsanbieter anzuschließen. Kosteneffizienz ist dabei zwingend nötig, weshalb häufig auf Passive Optische Netzwerke (PONs) und elektro-optische Komponenten (Detektoren, Modulatoren) von geringer Komplexität zurückgegriffen wird. Dessen Leistungsfähigkeit kann mit digitaler Signalverarbeitung verbessert werden. Neuartige optische Modulationsformate können ebenso eingesetzt werden, um eine gute spektrale Effizienz mit Hilfe komplexer Signalverteilung zu realisieren. Ein derartiges Modulationsformat ist Orthogonales Frequenzmultiplexverfahren (OFDM). Es bietet ein kompaktes Spektrum, Robustheit gegenüber chromatischer Dispersion und eine flexible Zuweisung der Signalträger im Spektrum [2]. Herkömmliche PONs nutzen das C-Band (1500nm) zum Downlink von Daten und das O-Band (1330nm) zum Uplink von Daten [3]–[9]. Das C-Band zeichnet sich durch eine geringe Dämpfung bei jedoch hoher chromatischer Dispersion aus [10]. Das O-Band hat fast keine chromatische Dispersion, jedoch eine höhere Dämpfung als das C-Band [10]. Dies ermöglicht den Einsatz einfacher Sender im O-Band wie zum Beispiel direkt-modulierte Laser (DML). Moderne PONs müssen einen parallelen Betrieb mit herkömmlichen Netzen erlauben. Aus diesem Grund werden im C-Band sowohl Uplink als auch Downlink vereint [11]. Ein DML verfügt als Nebeneffekt beim Senden über einen Chirp-Effekt [12], [13]. Dieser Chirp interagiert mit der chromatischen Dispersion (C-Band) der Glasfaser und erzeugt Träger-zu-Träger Mischung Übersprechen (SSII) nach einem direkt-detektierenden Empfänger [14]. Diese Störungen treten trotz der OFDM-typischen Robustheit gegenüber chromatischer Dispersion auf und erschweren den kosteneffizienten Einsatz OFDM-basierter Zugangsnetze. Der wesentliche Beitrag dieser Arbeit besteht in der Voraussage und Analyse der Auswirkungen von SSII auf Beeinträchtigungen der Signalqualität und dem Vorschlag und experimenteller Verifizierung von Kompensationstechniken. Eine analytische Formulierung zur Voraussage des Signal-Rausch-Verhältnises (SNR), bei OFDM basierten DML Übertragungen wird angegeben. Die vorgeschlagene Methode ist in der Lage, den Einfluss einzelner Träger auf die Reduzierung des gesamten SNRs zu ermitteln. Die Intensitäts- und Frequenzantwort typischer DMLs sind ebenso in der Formulierung berücksichtigt. Sie werden in einem vereinfachten Lasermodell präsentiert. Die Voraussagen dieser Formulierung werden mithilfe von Experimenten unter verschiedenen Bedingungen validiert [15]. Des Weiteren wird ein Algorithmus zur Bit-und-Leistungsadaption präsentiert. Dieser kann die Leistung und Übertragunskapazität für jeden Träger auf dem Kanal anpassen, so dass ein maximaler Durchsatz erzielt wird [16]. Abschließend wird ein adaptiver Equalizer präsentiert. Das gezeigte Optimierungsverfahren erlaubt eine effiziente Kompensation von SSII [17]. Durch den Einsatz dieses optimierten Equalizers konnte in Experimenten eine Kapazitätssteigerung von ≃33% erreicht werden [18].O crescimento das ligações de banda larga tem sido exponencial, e esta tendência manter-se-á no futuro previsível [1]. Uma rede de acesso é a ligação entre utilizadores e fornecedores de serviço, sendo um elemento chave no suporte do referido crescimento. Ao expandir a sua oferta de banda larga, um fornecedor de serviço tem, por um lado, de assegurar a sua migração através da compatibilidade com redes já existentes, e por outro lado, criar uma oferta atractiva para os consumidores. As redes de acesso são projectadas para suportar um grande número de utilizadores a diferentes distâncias do fornecedor de serviço, a viabilidade económica é obrigatória e é geralmente baseada no uso de Redes Ópticas Passivas (PONs) e componentes electro-ópticos de baixa complexidade (modulação/detecção directa), cujo desempenho pode ser melhorado através do uso de processamento digital de sinal com o intuito de mitigar limitações dos mesmos. Os mais recentes formatos de modulação também ajudam na obtenção de grande eficiência espectral assim como na distribuição avançada de sinal. Um destes formatos de modulação é Multiplexação por Divisão de Frequências Ortogonais (OFDM), que oferece um espectro compacto, é resiliente à dispersão cromática e possibilita a alocação flexível de subportadoras [2]. As redes já existentes usam a banda-C (1500nm) na ligação descendente e a banda-O (1330nm) na ligação ascendente [3]–[9]. A banda-C tem baixa atenuação apesar de ter elevada dispersão cromática [10]. A banda-O não tem practicamente dispersão cromática apesar da sua elevada atenuação [10], o que permite o uso de transmissores mais simples, tal como o Laser Directamente Modulado (DML). Os mais recentes sistemas PON devem permitir operação conjunta com redes já existentes. Por esta razão podem operar na banda-C tanto na ligação descendente como na ascendente [11]. Um DML tem chirp (variação da frequência de transmissão dependente da intensidade de emissão) como sub-producto da transmissão [12], [13]. O chirp interage com a dispersão cromática da fibra óptica (banda-C) criando Interferências de Mistura entre Subportadoras (SSII) num receptor de detecção directa [14]. Estas interferências podem ocorrer apesar da resiliência do OFDM à dispersão cromática e são uma das mais importantes limitações em sistemas de acesso economicamente viáveis baseados em OFDM. A principal contribuição deste trabalho é prever e analisar o impacto de SSII como limitação, propondo e verificando experimentalmente técnicas de mitigação. Um modelo analítico capaz de prever a Relação Sinal-Ruído (SNR) para transmissão com DML baseada em OFDM é derivada. Este modelo tem a capacidade de determinar a contribuição de cada subportadora para a degradação da SNR. As respostas em intensidade e frequência do DML são incluídas na formulação através de um modelo simplificado de laser. As previsões desta formulação são validadas experimentalmente sob várias condições [15]. Um algoritmo de adaptação de bit-e-potência também é proposto, este algoritmo adapta a potência e capacidade de cada subportadora ao canal, maximizando assim a capacidade total de transmissão [16]. Finalmente um equalizador adaptativo é apresentado. Um processo de optimização capaz de conseguir mitigação eficiente de SSII é proposto [17]. Resultados experimentais demonstram um aumento de capacidade de ≃33% ao usar o equalizador optimizado proposto [18].BMBF, 16BP1136, Neue Simulationsmodelle und Technologien zur Signalentzerrung und -überwachung für kosteneffiziente Zugangsnetz

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research

Respiratory support in patients with severe COVID-19 in the International Severe Acute Respiratory and Emerging Infection (ISARIC) COVID-19 study: a prospective, multinational, observational study

Background: Up to 30% of hospitalised patients with COVID-19 require advanced respiratory support, including high-flow nasal cannulas (HFNC), non-invasive mechanical ventilation (NIV), or invasive mechanical ventilation (IMV). We aimed to describe the clinical characteristics, outcomes and risk factors for failing non-invasive respiratory support in patients treated with severe COVID-19 during the first two years of the pandemic in high-income countries (HICs) and low middle-income countries (LMICs). Methods: This is a multinational, multicentre, prospective cohort study embedded in the ISARIC-WHO COVID-19 Clinical Characterisation Protocol. Patients with laboratory-confirmed SARS-CoV-2 infection who required hospital admission were recruited prospectively. Patients treated with HFNC, NIV, or IMV within the first 24 h of hospital admission were included in this study. Descriptive statistics, random forest, and logistic regression analyses were used to describe clinical characteristics and compare clinical outcomes among patients treated with the different types of advanced respiratory support. Results: A total of 66,565 patients were included in this study. Overall, 82.6% of patients were treated in HIC, and 40.6% were admitted to the hospital during the first pandemic wave. During the first 24 h after hospital admission, patients in HICs were more frequently treated with HFNC (48.0%), followed by NIV (38.6%) and IMV (13.4%). In contrast, patients admitted in lower- and middle-income countries (LMICs) were less frequently treated with HFNC (16.1%) and the majority received IMV (59.1%). The failure rate of non-invasive respiratory support (i.e. HFNC or NIV) was 15.5%, of which 71.2% were from HIC and 28.8% from LMIC. The variables most strongly associated with non-invasive ventilation failure, defined as progression to IMV, were high leukocyte counts at hospital admission (OR [95%CI]; 5.86 [4.83-7.10]), treatment in an LMIC (OR [95%CI]; 2.04 [1.97-2.11]), and tachypnoea at hospital admission (OR [95%CI]; 1.16 [1.14-1.18]). Patients who failed HFNC/NIV had a higher 28-day fatality ratio (OR [95%CI]; 1.27 [1.25-1.30]). Conclusions: In the present international cohort, the most frequently used advanced respiratory support was the HFNC. However, IMV was used more often in LMIC. Higher leucocyte count, tachypnoea, and treatment in LMIC were risk factors for HFNC/NIV failure. HFNC/NIV failure was related to worse clinical outcomes, such as 28-day mortality. Trial registration This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable

Thrombotic and hemorrhagic complications of COVID-19 in adults hospitalized in high-income countries compared with those in adults hospitalized in low- and middle-income countries in an international registry

Background: COVID-19 has been associated with a broad range of thromboembolic, ischemic, and hemorrhagic complications (coagulopathy complications). Most studies have focused on patients with severe disease from high-income countries (HICs). Objectives: The main aims were to compare the frequency of coagulopathy complications in developing countries (low- and middle-income countries [LMICs]) with those in HICs, delineate the frequency across a range of treatment levels, and determine associations with in-hospital mortality. Methods: Adult patients enrolled in an observational, multinational registry, the International Severe Acute Respiratory and Emerging Infections COVID-19 study, between January 1, 2020, and September 15, 2021, met inclusion criteria, including admission to a hospital for laboratory-confirmed, acute COVID-19 and data on complications and survival. The advanced-treatment cohort received care, such as admission to the intensive care unit, mechanical ventilation, or inotropes or vasopressors; the basic-treatment cohort did not receive any of these interventions. Results: The study population included 495,682 patients from 52 countries, with 63% from LMICs and 85% in the basic treatment cohort. The frequency of coagulopathy complications was higher in HICs (0.76%-3.4%) than in LMICs (0.09%-1.22%). Complications were more frequent in the advanced-treatment cohort than in the basic-treatment cohort. Coagulopathy complications were associated with increased in-hospital mortality (odds ratio, 1.58; 95% CI, 1.52-1.64). The increased mortality associated with these complications was higher in LMICs (58.5%) than in HICs (35.4%). After controlling for coagulopathy complications, treatment intensity, and multiple other factors, the mortality was higher among patients in LMICs than among patients in HICs (odds ratio, 1.45; 95% CI, 1.39-1.51). Conclusion: In a large, international registry of patients hospitalized for COVID-19, coagulopathy complications were more frequent in HICs than in LMICs (developing countries). Increased mortality associated with coagulopathy complications was of a greater magnitude among patients in LMICs. Additional research is needed regarding timely diagnosis of and intervention for coagulation derangements associated with COVID-19, particularly for limited-resource settings

Respiratory support in patients with severe COVID-19 in the International Severe Acute Respiratory and Emerging Infection (ISARIC) COVID-19 study: a prospective, multinational, observational study

Background: Up to 30% of hospitalised patients with COVID-19 require advanced respiratory support, including high-flow nasal cannulas (HFNC), non-invasive mechanical ventilation (NIV), or invasive mechanical ventilation (IMV). We aimed to describe the clinical characteristics, outcomes and risk factors for failing non-invasive respiratory support in patients treated with severe COVID-19 during the first two years of the pandemic in high-income countries (HICs) and low middle-income countries (LMICs). Methods: This is a multinational, multicentre, prospective cohort study embedded in the ISARIC-WHO COVID-19 Clinical Characterisation Protocol. Patients with laboratory-confirmed SARS-CoV-2 infection who required hospital admission were recruited prospectively. Patients treated with HFNC, NIV, or IMV within the first 24 h of hospital admission were included in this study. Descriptive statistics, random forest, and logistic regression analyses were used to describe clinical characteristics and compare clinical outcomes among patients treated with the different types of advanced respiratory support. Results: A total of 66,565 patients were included in this study. Overall, 82.6% of patients were treated in HIC, and 40.6% were admitted to the hospital during the first pandemic wave. During the first 24 h after hospital admission, patients in HICs were more frequently treated with HFNC (48.0%), followed by NIV (38.6%) and IMV (13.4%). In contrast, patients admitted in lower- and middle-income countries (LMICs) were less frequently treated with HFNC (16.1%) and the majority received IMV (59.1%). The failure rate of non-invasive respiratory support (i.e. HFNC or NIV) was 15.5%, of which 71.2% were from HIC and 28.8% from LMIC. The variables most strongly associated with non-invasive ventilation failure, defined as progression to IMV, were high leukocyte counts at hospital admission (OR [95%CI]; 5.86 [4.83–7.10]), treatment in an LMIC (OR [95%CI]; 2.04 [1.97–2.11]), and tachypnoea at hospital admission (OR [95%CI]; 1.16 [1.14–1.18]). Patients who failed HFNC/NIV had a higher 28-day fatality ratio (OR [95%CI]; 1.27 [1.25–1.30]). Conclusions: In the present international cohort, the most frequently used advanced respiratory support was the HFNC. However, IMV was used more often in LMIC. Higher leucocyte count, tachypnoea, and treatment in LMIC were risk factors for HFNC/NIV failure. HFNC/NIV failure was related to worse clinical outcomes, such as 28-day mortality. Trial registration This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable

Characteristics and outcomes of an international cohort of 600 000 hospitalized patients with COVID-19

Background: We describe demographic features, treatments and clinical outcomes in the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) COVID-19 cohort, one of the world's largest international, standardized data sets concerning hospitalized patients. Methods: The data set analysed includes COVID-19 patients hospitalized between January 2020 and January 2022 in 52 countries. We investigated how symptoms on admission, co-morbidities, risk factors and treatments varied by age, sex and other characteristics. We used Cox regression models to investigate associations between demographics, symptoms, co-morbidities and other factors with risk of death, admission to an intensive care unit (ICU) and invasive mechanical ventilation (IMV). Results: Data were available for 689 572 patients with laboratory-confirmed (91.1%) or clinically diagnosed (8.9%) SARS-CoV-2 infection from 52 countries. Age [adjusted hazard ratio per 10 years 1.49 (95% CI 1.48, 1.49)] and male sex [1.23 (1.21, 1.24)] were associated with a higher risk of death. Rates of admission to an ICU and use of IMV increased with age up to age 60&nbsp;years then dropped. Symptoms, co-morbidities and treatments varied by age and had varied associations with clinical outcomes. The case-fatality ratio varied by country partly due to differences in the clinical characteristics of recruited patients and was on average 21.5%. Conclusions: Age was the strongest determinant of risk of death, with a ∼30-fold difference between the oldest and youngest groups; each of the co-morbidities included was associated with up to an almost 2-fold increase in risk. Smoking and obesity were also associated with a higher risk of death.&nbsp;The size of our international database and the standardized data collection method make this study a comprehensive international description of COVID-19 clinical features. Our findings may inform strategies that involve prioritization of patients hospitalized with COVID-19 who have a higher risk of death

Paediatric COVID-19 mortality: a database analysis of the impact of health resource disparity

Background The impact of the COVID-19 pandemic on paediatric populations varied between high-income countries (HICs) versus low-income to middle-income countries (LMICs). We sought to investigate differences in paediatric clinical outcomes and identify factors contributing to disparity between countries.Methods The International Severe Acute Respiratory and Emerging Infections Consortium (ISARIC) COVID-19 database was queried to include children under 19 years of age admitted to hospital from January 2020 to April 2021 with suspected or confirmed COVID-19 diagnosis. Univariate and multivariable analysis of contributing factors for mortality were assessed by country group (HICs vs LMICs) as defined by the World Bank criteria.Results A total of 12 860 children (3819 from 21 HICs and 9041 from 15 LMICs) participated in this study. Of these, 8961 were laboratory-confirmed and 3899 suspected COVID-19 cases. About 52% of LMICs children were black, and more than 40% were infants and adolescent. Overall in-hospital mortality rate (95% CI) was 3.3% [=(3.0% to 3.6%), higher in LMICs than HICs (4.0% (3.6% to 4.4%) and 1.7% (1.3% to 2.1%), respectively). There were significant differences between country income groups in intervention profile, with higher use of antibiotics, antivirals, corticosteroids, prone positioning, high flow nasal cannula, non-invasive and invasive mechanical ventilation in HICs. Out of the 439 mechanically ventilated children, mortality occurred in 106 (24.1%) subjects, which was higher in LMICs than HICs (89 (43.6%) vs 17 (7.2%) respectively). Pre-existing infectious comorbidities (tuberculosis and HIV) and some complications (bacterial pneumonia, acute respiratory distress syndrome and myocarditis) were significantly higher in LMICs compared with HICs. On multivariable analysis, LMIC as country income group was associated with increased risk of mortality (adjusted HR 4.73 (3.16 to 7.10)).Conclusion Mortality and morbidities were higher in LMICs than HICs, and it may be attributable to differences in patient demographics, complications and access to supportive and treatment modalities