Clinical traits with inflammation characterization of long COVID and correlation with one-year recovery after COVID-19-linked hospitalization

By Shanet Susan AlexApr 26 2022Reviewed by Danielle Ellis, B.Sc.

In a recent study posted in The Lancet Respiratory Medicine journal, researchers presented the clinical traits with inflammation characterization of long coronavirus disease (COVID) and correlation with one-year recovery after coronavirus disease 2019 (COVID-19)-linked hospitalization.

Background

To date, the COVID-19 pandemic has caused over 500 million severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection cases worldwide, with >21 million cases in the United Kingdom (UK), including more than 820,000 related hospitalizations. This population is at significant risk of long-term health problems, including decreased health-related quality of life and physical function, six months following hospital discharge. It is critical to understand both the longer-term trajectory of recovery to recognize ongoing healthcare requirements and the needed reaction by medical systems and policymakers for this already vast and ever-increasing population. 

The National Institute for Health and Care Excellence (NICE) defines long COVID as SARS-CoV-2 infection symptoms lasting longer than four to 12 weeks after COVID-19. Furthermore, the World Health Organization (WHO) defines the post-COVID-19 condition as occurring in people who have had a history of confirmed or probable SARS CoV-2 infection, typically three months after the onset of COVID-19, with symptoms lasting at least two months and cannot attribute to another diagnosis. Of note, there are no efficacious non-pharmacological or pharmacological therapies for long COVID patients. 

About the study

In the current study, the investigators aimed to analyze the recovery one year following hospital discharge for SARS-CoV-2 infection, identify the factors correlated with patient-perceived recovery, and discover potential therapeutic targets by characterizing the underpinning inflammatory statuses of the authors' priorly reported COVID-19 recovery clusters at five months post-hospital discharge.  

The researchers used data from the post-hospitalization COVID-19 study (PHOSP-COVID), a prospective, longitudinal cohort study that recruited individuals aged 18 years or older who were discharged from hospitals with SARS-CoV-2 infection in the UK. Recovery was determined using patient-reported organ function, physical performance, and outcome measures at five months and one year following hospital release. Further, they were categorized by both recovery clusters and patient-perceived recovery. For patient-perceived recovery at one-year, hierarchical logistic regression modeling was used. 

Clinical outcomes at five months were used in a cluster analysis utilizing the clustering large applications k-medoids technique. Plasma was tested for inflammatory protein profiling at the five-month visit. The international standard randomized controlled trial number (ISRCTN) registry number for this study was ISRCTN10980107, and recruitment is still underway.

Results

A total of 2320 subjects were examined five months after release from the hospital following COVID-19, between March 7, 2020, and April 18, 2021, with 807 completing both the five-month and one-year visits. There were 505 males and 279 women among the 807 patients, with a mean age of 58.7 years, and 224 participants required invasive mechanical breathing (WHO class 7–9). Further, the percentage of patients claiming complete recovery remained steady between five months (501 in 1965) and one year (232 of 804).

Obesity, invasive mechanical ventilation, and female sex were all linked to a lower likelihood of reporting full recovery in one year. The previously reported four clusters: mild, moderate with cognitive impairment, severe, and very severe, corresponding to the severity of cognitive impairment, physical health, and mental health at five months, were confirmed by cluster analysis of 1636 patients.

In both the moderate plus cognitive impairment and very severe groups, the investigators discovered elevated inflammatory mediators of tissue damage and repair compared to the mild cluster, including interleukin 6 (IL-6) levels, which were higher in both comparisons of 626 patients. The researchers discovered a significant shortfall in the median health-related quality of life (EQ-5D-5L) utility index via retrospective assessment after five months and one year following COVID-19-related hospital discharge compared to before SARS-CoV-2-linked hospitalization.

The median EQ-5D-5L utility index was 0.88 before COVID-19-related hospital admission, 0.74 at five months, and 0.75 at one year after SARS-CoV-2-associated hospitalization, indicating minimal progress across all outcome measures in the entire cohort and within the four clusters at the one-year post-COVID-19 hospitalization period.

Conclusions

The study findings demonstrated that the long-term effects of COVID-19 hospitalization were evident one year after hospital discharge across a variety of health categories, with only a minute percentage of the present sample reporting a total recovery. Compared to before SARS-CoV-2-linked admission to the hospital, the patient's reported health-related quality of life was worse after a year. The authors then stated that obesity and systemic inflammation were potentially curable conditions that should be investigated further in clinical studies.

Overall, the present data revealed a critical need for medical services to support the large and rapidly growing long COVID patient population. The authors suggested that long COVID might become a significantly prevalent novel long-term illness if appropriate therapies were not found. These findings further support using a precision-medicine strategy to tailor treatments to the adequate phenotype to improve health-related quality of life in people with long COVID.