Hypothyroidism does not lead to worse prognosis in COVID-19: findings from the Brazilian COVID-19 registry
Authors: Pereira Daniella Nunes , Gontijo Silveira Leticia Ferreira , Moreira Guimarães Milena Maria , Polanczyk Carísi Anne , Sousa Nunes Aline Gabrielle , de Moura Costa André Soares , Farace Barbara Lopes , Rodrigues Cimini Christiane Corrêa , de Carvalho Cíntia Alcantara , Ponce Daniela , Roesch Eliane Würdig , Fernandes Manenti Euler Roberto , Lucas Fernanda Barbosa , Rodrigues Fernanda d’Athayde , Anschau Fernando , Aranha Fernando Graça , Bartolazzi Frederico , Vietta Giovanna Grunewald , Nascimento Guilherme Fagundes , Duani Helena , Vianna Heloisa Reniers , Guimarães Henrique Cerqueira , Martins Costa Jamille Hemétrio Salles , Lyra Batista Joanna d’Arc , de Alvarenga Joice Coutinho , Chatkin José Miguel , de Morais Júlia Drumond Parreiras , Machado-Rugolo Juliana , Ruschel Karen Brasil , Pinheiro Lílian Santos , Monteiro Menezes Luanna Silva , Ferreira Couto Luciana Siuves , Kopittke Luciane , de Castro Luís César , Nasi Luiz Antônio , de Souza Cabral Máderson Alvares , Floriani Maiara Anschau , Souza Maíra Dias , Carneiro Marcelo , Camargos Bicalho Maria Aparecida , de Godoy Mariana Frizzo , Alves Nogueira Matheus Carvalho , Guimarães Júnior Milton Henriques , Severino Sampaio Natália da Cunha , de Oliveira Neimy Ramos , Assaf Pedro Ledic , Finger Renan Goulart , Campos Roberta Xavier , Menezes Rochele Mosmann , Francisco Saionara Cristina , Alvarenga Samuel Penchel , Mereilles Guimarães Silvana Mangeon , Araújo Silvia Ferreira , Oliveira Talita Fischer , Oliveira Diniz Thulio Henrique , Ramires Yuri Carlotto , de Almeida Cenci Evelin Paola , de Oliveira Thainara Conceição , Schwarzbold Alexandre Vargas , Ziegelmann Patricia Klarmann , Pozza Roberta , Pires Magda Carvalho , Marcolino Milena Soriano 
Published: November 2021

Background

It is not clear whether previous thyroid diseases influence the course and outcomes of COVID-19. The study aims to compare clinical characteristics and outcomes of COVID-19 patients with and without hypothyroidism.

Methods

The study is a part of a multicentric cohort of patients with confirmed COVID-19 diagnosis, including data collected from 37 hospitals. Matching for age, sex, number of comorbidities and hospital was performed to select the patients without hypothyroidism for the paired analysis.

Results

From 7,762 COVID-19 patients, 526 had previously diagnosed hypothyroidism (50%) and 526 were selected as matched controls. The median age was 70 (interquartile range 59.0-80.0) years-old and 68.3% were females. The prevalence of underlying comorbidities were similar between groups, except for coronary and chronic kidney diseases, that had a higher prevalence in the hypothyroidism group (9.7% vs. 5.7%, p=0.015 and 9.9% vs. 4.8%, p=0.001, respectively). At hospital presentation, patients with hypothyroidism had a lower frequency of respiratory rate > 24 breaths per minute (36.1% vs 42.0%; p=0.050) and need of mechanical ventilation (4.0% vs 7.4%; p=0.016). D-dimer levels were slightly lower in hypothyroid patients (2.3 times higher than the reference value vs 2.9 times higher; p=0.037). In-hospital management was similar between groups, but hospital length-of-stay (8 vs 9 days; p=0.029) and mechanical ventilation requirement (25.4% vs. 33.1%; p=0.006) were lower for patients with hypothyroidism. There was a trend of lower in-hospital mortality in patients with hypothyroidism (22.1% vs. 27.0%; p=0.062).

Conclusion

In this large Brazilian COVID-19 Registry, patients with hypothyroidism had a lower requirement of mechanical ventilation, and showed a trend of lower in-hospital mortality. Therefore, hypothyroidism does not seem to be associated with a worse prognosis, and should not be considered among the comorbidities that indicate a risk factor for COVID-19 severity.