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The longitudinal progression of health outcomes in COVID-19 survivors with different initial disease severity

In a recent study published in The Lancet Respiratory Medicine, researchers determined the evolution of health outcomes in individuals hospitalized due to acute severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Wuhan, China. They also tracked the recovery status of these coronavirus disease 2019 (COVID-19) survivors for up to two years.

About the study

In the current longitudinal cohort study, researchers recruited individuals hospitalized due to COVID-19 in the Jin Yin-tan hospital of Wuhan, China, and later discharged between January 7 and May 29, 2020.

The team divided the study participants into three groups based on the infection severity scale. While patients in the scale 3 group did not need supplemental oxygen, those in the scale 4 received supplemental oxygen, and the group of patients in the scale 5 to 6 required high-flow nasal cannula or invasive or non-invasive mechanical ventilation.

The researchers estimated the correlation coefficients between different symptoms in COVID-19 survivors at three-time points, six months, 12 months, and two years after the symptom onset, and presented them as a heatmap.

The control group individuals were age and sex-matched to the test subjects. They had the same underlying comorbidities but no history of COVID-19. The researchers assessed the same parameters, including modified British Medical Research Council (mMRC) dyspnoea scale and HRQoL for the control group.

They performed laboratory tests, a six-minute walking distance (6MWD) test, and a series of questionnaires to assess each individual’s symptoms, including mental health, health-related quality of life (HRQoL), and health-care usage after hospital discharge. The researchers also compared the lung function of COVID-19 survivors in the three study groups and between COVID-19 survivors and their matched controls using a stringent Bonferroni correction. They set the α threshold for the former comparison at 5·56×10-³ and the latter at 0·0167.

For statistical analyses of the association between long COVID symptoms and health outcomes at a two-year follow-up visit, the team used multivariable-adjusted logistic regression models and generalized linear regression models for categorical and continuous outcomes.

Furthermore, the team used the χ² test, Kruskal-Wallis test, or Fisher’s exact or Mann-Whitney U tests to draw comparisons between the clinical and demographic characteristics of three study groups, as deemed necessary.

Study findings

In total, 2469 COVID-19 patients were discharged from Jin Yin-tan Hospital between January 7 and May 29, 2020, of which 1192 COVID-19 survivors completed assessments at the three follow-up visits. However, only 1119 individuals attended the in-person interview two years after the infection. The average age of COVID-19 survivors at the time of hospital discharge was 57 years, and 46% of them were women.

Fatigue and muscle weakness were the most frequent sequelae symptoms in the majority of COVID-19 survivors. The symptom frequency diminished to 68% and 55% at six months and two years, respectively.

The proportion of COVID-19 survivors with an mMRC score of at least one was 26% at six months but reduced to 14% at two years. HRQoL, especially in terms of anxiety or depression, continued to improve across all the study groups. Accordingly, the proportion of COVID-19 survivors with symptoms of anxiety or depression decreased from 23% to 12% from six months to two years.

In the three study groups with varying initial disease severity, the proportion of COVID-19 survivors with a 6MWD less than the lower limit of the normal range declined continuously. Notably, 89% of COVID-19 survivors returned to work after two years.

Survivors with persistent COVID-19 symptoms at two years had lower HRQoL. Additionally, they were not fit to exercise, had mental health issues, and used more health-care support after discharge than survivors without such symptoms. Compared to controls, COVID-19 survivors suffered more from pain, discomfort, as well as anxiety, and depression at two years.

Additionally, 65% of those who had received respiratory support during hospitalization had lung diffusion impairment, while only 36% of controls faced this problem. Likewise, 62% of such patients suffered from reduced residual volume and 39% from total lung capacity issues. Conversely, only 20% and 6% of controls faced reduced residual volume and total lung capacity issues.


The study data demonstrated that the majority of COVID-19 survivors showed significantly improved physical and mental health outcomes, and a staggering 89% of them even returned to work after two years. However, the burden of sequelae symptoms remained high; therefore, they had a lower health status than the general population. Indeed, there is an urgent need to intervene and curb the risk of long COVID among patients hospitalized due to COVID-19.

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