Clinical characteristics and outcomes of COVID-19 patients with preexisting dementia: a large multicenter propensity-matched Brazilian cohort study
Authors: Bicalho Maria Aparecida Camargos , Aliberti Márlon Juliano Romero , Delfino-Pereira Polianna , Chagas Victor Schulthais , Rosa Patryk Marques da Silva , Pires Magda Carvalho , Ramos Lucas Emanuel Ferreira , Bezerra Adriana Falangola Benjamin , de Castro Feres Ana Beatriz , dos Reis Gomes Angélica Gomides , Bhering Angelinda Rezende , Pessoa Bruno Porto , Silva Carla Thais Cândida Alves da , Cimini Christiane Corrêa Rodrigues , Suemoto Claudia Kimie , Dias Cristiana Andrade Coelho , Carazai Daniela dos Reis , Ponce Daniela , Rios Danyelle Romana Alves , Manenti Euler , Anschau Fernando , Batista Joanna d‘Arc Lyra , Alvarenga Joice Coutinho de , Viguini Julia Avancini , Zanellato Julia Mariot , Rugolo Juliana Machado , Ruschel Karen Brasil , do Nascimento Leticia , Menezes Luanna Silva Monteiro , Oliveira Lucas Moyses Carvalho de , Castro Luís César de , Nasi Luiz Antônio , Carneiro Marcelo , Ferreira Maria Angélica Pires , Godoy Mariana Frizzo de , Guimarães-Júnior Milton Henriques , Oliveira Neimy Ramos de , Ziegelmann Patricia Klarmann , Porto Paula Fonseca , Mendes Paulo Mascarenhas , Paraíso Pedro Gibson , Reis Priscilla Pereira dos , Francisco Saionara Cristina , Araújo Silvia Ferreira , Avelino-Silva Thiago Junqueira , Marcolino Milena Soriano 
Published: January 2024

Abstract
Background
Although dementia has emerged as an important risk factor for severe SARS-CoV-2 infection, results on COVID-19-related complications and mortality are not consistent. We examined the clinical presentations and outcomes of COVID-19 in a multicentre cohort of in-hospital patients, comparing those with and without dementia.

Methods
This retrospective observational study comprises COVID-19 laboratory-confirmed patients aged ≥ 60 years admitted to 38 hospitals from 19 cities in Brazil. Data were obtained from electronic hospital records. A propensity score analysis was used to match patients with and without dementia (up to 3:1) according to age, sex, comorbidities, year, and hospital of admission. Our primary outcome was in-hospital mortality. We also assessed admission to the intensive care unit (ICU), invasive mechanical ventilation (IMV), kidney replacement therapy (KRT), sepsis, nosocomial infection, and thromboembolic events.

Results
Among 1,556 patients included in the study, 405 (4.5%) had a diagnosis of dementia and 1,151 were matched controls. When compared to matched controls, patients with dementia had a lower frequency of dyspnoea, cough, myalgia, headache, ageusia, and anosmia; and higher frequency of fever and delirium. They also had a lower frequency of ICU admission (32.7% vs. 47.1%, p < 0.001) and shorter ICU length of stay (7 vs. 9 days, p < 0.026), and a lower frequency of sepsis (17% vs. 24%, p = 0.005), KRT (6.4% vs. 13%, p < 0.001), and IVM (4.6% vs. 9.8%, p = 0.002). There were no differences in hospital mortality between groups.

Conclusion
Clinical manifestations of COVID-19 differ between older inpatients with and without dementia. We observed that dementia alone could not explain the higher short-term mortality following severe COVID-19. Therefore, clinicians should consider other risk factors such as acute morbidity severity and baseline frailty when evaluating the prognosis of older adults with dementia hospitalised with COVID-19.