In a recent study posted to The research site* preprint server, researchers performed symptom assessment, cognitive tests and physical measurements after an infection with coronavirus disease 2019 (COVID-19).
Various studies have reported acute symptoms manifested in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, extensive research is needed to establish post-Symptoms of covid-19 in non-hospitalized patients.
About the study
The researchers in this study examined the disease outcomes after SARS-CoV-2 infection in individuals with and without prior infection in a large population in Iceland.
The study included 3,602 people aged 18 and over who had a reported history of COVID-19 infection. Participants were tested positive for SARS-CoV-2 at least five months before September 2020 or February 2021. The team also included individuals who had participated in the dHS study prior to the pandemic, allowing the team to make comparisons in individual characteristics before and after after infection.
Individuals with a previous infection were confirmed by the presence of antibodies, while positive patients were identified by either performing quantitative polymerase chain reaction (qPCR) tests on high-risk cohorts or population screening. The control group consisted of individuals who had previously participated in the modified deCODE health study (dHS) before the June 2016 to March 2020 pandemic, called the historical controls, as well as participants in the dHS study from September 2021 to September 2021 who had no history of COVID-19 infection, called the modern controls.
The study included questionnaires regarding the individual’s health and lifestyle along with several blood tests, physiological and cognitive tests. The team also examined possible symptoms of depression, anxiety, stress, fatigue, and health anxiety by adding questionnaires, including generalized anxiety disorder-7 (GAD-7), perceived stress scale (PSS), patient health questionnaire-9 (PHQ-9), symptom impact questionnaire ( SIQR) and short health anxiety inventory (SHAI). Health-related quality of life was also assessed using a 36-element short-form survey (36-SF) and satisfaction with the life scale (SWLS).
The team reported the association between the history of previous COVID-19 infection and the results of (1) questionnaires C19Q, GAD-7, PHQ-9, PSS, SHAI, SIQR, SWLS, and 36-SF; (2) measurements of weight, height, body mass index (BMI), heart rate, blood pressure, body composition, and oxygen saturation; (3) cognitive tests and; (4) blood tests.
The study results showed that dHS included 3,602 eligible Icelanders infected with SARS-CoV-2. Infected cases had a mean age of 46 years, with 51% of cases being women. In addition, almost 33% of participants had obesity, 18% had asthma, and 11% were immunocompromised.
The study also included a total of 14,388 controls, including 546 contemporary and 13,842 historical participants. The control cohort had a mean age of 56 years, with 57% of the group being women.
Approximately 40% of participants reported mild to severe COVID-19 symptoms, while 5% of cases required hospitalization due to the severity of COVID-19. The team noted that women and older participants had a greater chance of reporting a more serious acute COVID-19 infection along with people with obesity, asthma, and other comorbidities.
The participants themselves reported that up to five to six months after the infection, 33% of the total cases had not fully recovered from the disease, with 5% still showing severe symptoms. But 13 months after infection, 21% had not yet recovered and 1% had severe symptoms. Furthermore, the evaluation of quality of life and mental health showed fewer symptoms of stress in the case patients than in the control cohort.
The physiological tests performed showed that symptoms associated with altered taste and smell, including hyposmia, partial anosmia, and partial ageusia, were more commonly reported by the case patients than the controls. In addition, tests evaluating odor showed higher results over time after acute infection.
A total of 30% of cases and 15% of the control group had prolonged COVID symptoms. Case patients were 2.5 times more likely to show prolonged COVID symptoms than controls. In addition, individuals with comorbidities were 3.2 times more likely to experience long-term COVID. In particular, women and individuals with more severe infections and high-risk disease states, including compromised immunity, heart failure, and coronary artery disease, had a greater chance of suffering from long-term COVID.
The results of the study showed that several different symptoms were more prevalent in COVID-19 infected patients than among control participants. The researchers believe that the differences between symptoms and goals indicate a degree of response bias in self-reported symptoms, while conventional tests present a more complicated response paradigm among infected individuals.
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