Dinâmica de carga viral em pacientes com SARS-CoV-2
Data
2023-05-26
Autores
Faíco Filho, Klinger Soares 
Orientadores
Bellei, Nancy Cristina Junqueira
Tipo
Tese de doutorado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Objetivo: Avaliar as metodologias disponíveis em pacientes com diferentes condições de risco, fases clínicas e com desfechos clínicos diversos, no cenário dinâmico da evolução viral da pandemia no Brasil e no mundo e a possibilidade do advento de novas técnicas diagnósticas. Métodos: No primeiro estudo incluímos pacientes com diagnóstico de COVID-19 e utilizamos os valores de Cycle threshold (Ct) obtidos através da coleta de swab nasofaríngeo e realização de ensaio de RT-PCR. Os pacientes foram estratificados conforme grupo etário, gravidade da doença e desfecho. Já no segundo estudo foram incluídos pacientes com suspeita de COVID-19 admitidos no departamento de Emergência e utilizado um teste de antígeno imunocromatográfico para diagnóstico e analisado suas características em comparação ao teste padrão-ouro, o RT-PCR. Resultados: No primeiro estudo avaliamos 875 pacientes, 50,1% (439/875) foram classificados como tendo doença leve (pacientes não hospitalizados), 30,4% (266/875) moderada (hospitalizados na enfermaria) e 19, 5% (170/875) doença grave (admitidos em unidade de terapia intensiva). Um valor de Ct < 25 (472/875) indicou uma alta carga viral, que foi independentemente associada à mortalidade (odds ratio [OR]: 2,93; IC 95%: 1,87–4,60; p< 0,0001). No segundo estudo, o teste de antígeno em relação ao RT-PCR usando valores de Ct ≤ 40 como limite superior para positividade, o teste de antígeno mostrou uma sensibilidade geral de 84,3% (95% CI 75‒93,8%) e 98,2% (95% CI 96 ‒98,8%) especificidade geral. Para valores de Ct ≤ 25 (n= 37), o teste de antígeno apresentou 97% de sensibilidade. Conclusão: A carga viral elevada está associada ao pior prognóstico de pacientes durante a internação e é decisiva na sensibilidade de testes de antígenos.
Objective: To evaluate the available methodologies in patients with different risk conditions, clinical phases, and diverse clinical outcomes in the dynamic scenario of the viral evolution of the pandemic in Brazil and the world, and beyond the possibility of the advent of new diagnostic techniques. Methods: In the first study, we included patients diagnosed with COVID19 and used the Cycle threshold (Ct) values obtained through nasopharyngeal swab collection and RTPCR assay. Patients were stratified according to age group, disease severity, and outcome. In the second study, patients with suspected COVID19 admitted to the Emergency department were included, and an immunochromatographic antigen test was used for diagnosis, and their characteristics were analyzed compared to the gold standard test, RTPCR. Results: In the first study, we evaluated 875 patients, 50.1% (439/875) were classified as having mild disease (nonhospitalized patients), 30.4% (266/875) moderate (hospitalized in the ward), and 19.5% (170/875) severe disease (admitted to the intensive care unit). A Ct value < 25 (472/875) indicated a high viral load, which was independently associated with mortality (odds ratio [OR]: 2.93; 95% CI: 1.874.60; P < 0.0001). In the second study, compared to RTPCR using Ct values ≤ 40 as the upper limit for positivity, the antigen test showed an overall sensitivity of 84.3% (95% CI 7593.8%) and overall specificity of 98.2% (95% CI 9698.8%). For Ct values ≤ 25 (n = 37), the antigen test showed 97% sensitivity. Conclusion: High viral load is associated with worse prognosis in hospitalized patients and is decisive in the sensitivity of antigen tests.
Objective: To evaluate the available methodologies in patients with different risk conditions, clinical phases, and diverse clinical outcomes in the dynamic scenario of the viral evolution of the pandemic in Brazil and the world, and beyond the possibility of the advent of new diagnostic techniques. Methods: In the first study, we included patients diagnosed with COVID19 and used the Cycle threshold (Ct) values obtained through nasopharyngeal swab collection and RTPCR assay. Patients were stratified according to age group, disease severity, and outcome. In the second study, patients with suspected COVID19 admitted to the Emergency department were included, and an immunochromatographic antigen test was used for diagnosis, and their characteristics were analyzed compared to the gold standard test, RTPCR. Results: In the first study, we evaluated 875 patients, 50.1% (439/875) were classified as having mild disease (nonhospitalized patients), 30.4% (266/875) moderate (hospitalized in the ward), and 19.5% (170/875) severe disease (admitted to the intensive care unit). A Ct value < 25 (472/875) indicated a high viral load, which was independently associated with mortality (odds ratio [OR]: 2.93; 95% CI: 1.874.60; P < 0.0001). In the second study, compared to RTPCR using Ct values ≤ 40 as the upper limit for positivity, the antigen test showed an overall sensitivity of 84.3% (95% CI 7593.8%) and overall specificity of 98.2% (95% CI 9698.8%). For Ct values ≤ 25 (n = 37), the antigen test showed 97% sensitivity. Conclusion: High viral load is associated with worse prognosis in hospitalized patients and is decisive in the sensitivity of antigen tests.