Coronavirus Pneumonia: Outcomes and Characteristics of Patients in an Inner-City Area after 3 Months of Infection

Pulmonary function 3-6 months after acute COVID-19: A systematic review and multicentre cohort study

Aims

To describe pulmonary function 3-6 months following acute COVID-19, to evaluate potential predictors of decreased pulmonary function and to review literature for the effect of COVID-19 on pulmonary function.

Materials and methods

A systematic review and cohort study were conducted. Within the P4O2 COVID-19 cohort, 95 patients aged 40-65 years were recruited from outpatient post-COVID-19 clinics in five Dutch hospitals between May 2021-September 2022. At 3-6 months post COVID-19, medical records data and biological samples were collected and questionnaires were administered. In addition, pulmonary function tests (PFTs), including spirometry and transfer factor, were performed. To identify factors associated with PFTs, linear regression analyses were conducted, adjusted for covariates.

Results

In PFTs (n = 90), mean ± SD % of predicted was 89.7 ± 18.2 for forced vital capacity (FVC) and 79.8 ± 20.0 for transfer factor for carbon monoxide (DLCO). FVC was

Conclusion

A low DLCO 3-6 months following acute COVID-19 was observed more often than a low FVC, both in the P4O2 COVID-19 study and the literature review.

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Key Words

• Long COVID
• Post COVID-19
• Pulmonary function
• Transfer factor for carbon monoxide

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Affiliation(s)

Merel E.B. Cornelissen Department of Pulmonary Medicine, Amsterdam UMC, University of Amsterdam, 1105, AZ Amsterdam, the Netherlands Amsterdam Institute for Infection and Immunity, Amsterdam, the Netherlands Amsterdam Public Health, Amsterdam, the Netherlands
Asabi Leliveld Department of Pulmonary Medicine, Amsterdam UMC, University of Amsterdam, 1105, AZ Amsterdam, the Netherlands Amsterdam Institute for Infection and Immunity, Amsterdam, the Netherlands Amsterdam Public Health, Amsterdam, the Netherlands
Nadia Baalbaki Department of Pulmonary Medicine, Amsterdam UMC, University of Amsterdam, 1105, AZ Amsterdam, the Netherlands Amsterdam Institute for Infection and Immunity, Amsterdam, the Netherlands Amsterdam Public Health, Amsterdam, the Netherlands
Debbie Gach Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, the Netherlands School of Nutrition and Translational Research in Metabolism, Faculty of Health, Medicine and Life Sciences, Maastricht University, the Netherlands
Ivo van der Lee Department of Pulmonology, Spaarne Hospital, the Netherlands
Esther J. Nossent Department of Pulmonary Medicine, Amsterdam UMC, University of Amsterdam, 1105, AZ Amsterdam, the Netherlands
Lizan D. Bloemsma Department of Pulmonary Medicine, Amsterdam UMC, University of Amsterdam, 1105, AZ Amsterdam, the Netherlands Amsterdam Institute for Infection and Immunity, Amsterdam, the Netherlands Amsterdam Public Health, Amsterdam, the Netherlands
Anke H. Maitland-van der Zee Department of Pulmonary Medicine, Amsterdam UMC, University of Amsterdam, 1105, AZ Amsterdam, the Netherlands Amsterdam Institute for Infection and Immunity, Amsterdam, the Netherlands Amsterdam Public Health, Amsterdam, the Netherlands

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Systematic Review of the Prevalence of Long COVID

Background

Long COVID occurs in those infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) whose symptoms persist or develop beyond the acute phase. We conducted a systematic review to determine the prevalence of persistent symptoms, functional disability, or pathological changes in adults or children at least 12 weeks postinfection.

Methods

We searched key registers and databases from January 1, 2020 to November 2, 2021, limited to publications in English and studies with at least 100 participants. Studies in which all participants were critically ill were excluded. Long COVID was extracted as prevalence of at least 1 symptom or pathology, or prevalence of the most common symptom or pathology, at 12 weeks or later. Heterogeneity was quantified in absolute terms and as a proportion of total variation and explored across predefined subgroups (PROSPERO ID CRD42020218351).

Results

One hundred twenty studies in 130 publications were included. Length of follow-up varied between 12 weeks and 12 months. Few studies had low risk of bias. All complete and subgroup analyses except 1 had I² ≥90%, with prevalence of persistent symptoms range of 0%-93% (pooled estimate [PE], 42.1%; 95% prediction interval [PI], 6.8% to 87.9%). Studies using routine healthcare records tended to report lower prevalence (PE, 13.6%; PI, 1.2% to 68%) of persistent symptoms/pathology than self-report (PE, 43.9%; PI, 8.2% to 87.2%). However, studies systematically investigating pathology in all participants at follow up tended to report the highest estimates of all 3 (PE, 51.7%; PI, 12.3% to 89.1%). Studies of hospitalized cases had generally higher estimates than community-based studies.

Conclusions

The way in which Long COVID is defined and measured affects prevalence estimation. Given the widespread nature of SARS-CoV-2 infection globally, the burden of chronic illness is likely to be substantial even using the most conservative estimates.

Prevalence, risk factors and treatments for post-COVID-19 breathlessness: a systematic review and meta-analysis

Persistent breathlessness >28 days after acute COVID-19 infection has been identified as a highly debilitating post-COVID symptom. However, the prevalence, risk factors, mechanisms and treatments for post-COVID breathlessness remain poorly understood. We systematically searched PubMed and Embase for relevant studies published from 1 January 2020 to 1 November 2021 (PROSPERO registration number: CRD42021285733) and included 119 eligible papers. Random-effects meta-analysis of 42 872 patients with COVID-19 reported in 102 papers found an overall prevalence of post-COVID breathlessness of 26% (95% CI 23-29) when measuring the presence/absence of the symptom, and 41% (95% CI 34-48) when using Medical Research Council (MRC)/modified MRC dyspnoea scale. The pooled prevalence decreased significantly from 1-6 months to 7-12 months post-infection. Post-COVID breathlessness was more common in those with severe/critical acute infection, those who were hospitalised and females, and was less likely to be reported by patients in Asia than those in Europe or North America. Multiple pathophysiological mechanisms have been proposed (including deconditioning, restrictive/obstructive airflow limitation, systemic inflammation, impaired mental health), but the body of evidence remains inconclusive. Seven cohort studies and one randomised controlled trial suggested rehabilitation exercises may reduce post-COVID breathlessness. There is an urgent need for mechanistic research and development of interventions for the prevention and treatment of post-COVID breathlessness.