A recent study published within the journal PLoS ONE reports that patients with severe coronavirus disease 2019 (COVID-19) are at a better risk of experiencing persistent pulmonary impairments, even 12 months after disease onset.

Study: One-fourth of COVID-19 patients have an impaired pulmonary function after 12 months of disease onset. Image Credit: fizkes / Shutterstock.com

Background

The COVID-19 pandemic, attributable to the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused unprecedented damage to the worldwide healthcare system, with greater than 770 million infections and 6.9 million deaths reported worldwide. A major proportion of COVID-19 patients proceed to experience several health complications, including pulmonary impairments, even after complete resolution of the acute infection, collectively known as long-COVID.

Reduced carbon monoxide diffusing capability, along with reduced alveolar volume, is probably the most distinguished pulmonary effect of SARS-CoV-2 infection. This reduction in pulmonary function primarily is determined by the disease severity through the acute infection phase.

Previous longitudinal studies have reported improved pulmonary functions in COVID-19 patients between eight and 12 months after disease onset. Nonetheless, these studies have primarily included severe COVID-19 patients requiring hospitalization.

In the present study, scientists compare pulmonary functions and determinants of pulmonary functions in mild, moderate, and severe COVID-19 patients during a one-year follow-up period after disease onset.

Study design

The present study included each hospitalized and non-hospitalized COVID-19 patients from the RECoVERED cohort study, which is an observational study comprising mild, moderate, and severe COVID-19 patients who’re longitudinally examined at regular intervals for various clinical parameters, including pulmonary functions.

A complete of 301 RECoVERED cohort study patients who underwent not less than one pulmonary test between May 2020 and December 2021 were included within the study. Diffusing capability for carbon monoxide and respiratory patterns were measured to evaluate the dynamics of pulmonary functions of patients over a period of 12 months after disease onset.

Data on sociodemographic features, clinical characteristics, symptoms, and health-related quality of life were collected through patient interviews and medical records. These parameters were analyzed to discover the determinants of impaired pulmonary functions.

Pulmonary function after COVID-19

Amongst 301 patients included within the study, 30%, 44%, and 26% experienced mild, moderate, and severe COVID-19, respectively. About 47% of the study cohort were hospitalized, 13% of whom were admitted to the intensive care unit (ICU).

Pulmonary functions of the patients were measured at one, six, and 12 months after disease onset. On the one-month time point, a reduced diffusion capability was observed in 26%, 23%, and 74% of mild, moderate, and severe COVID-19 patients, respectively.

No significant improvement in diffusion capability was observed in patients with mild infection through the study period. In contrast, moderately and severely infected patients exhibited continuous improvements in diffusion capability until 12 months after disease onset.

The evaluation of pulmonary function determinants revealed that older age, female sex, higher variety of comorbidities, and disease severity during acute infection were significantly related to slower improvement in diffusion capability over time.

A significantly reduced diffusion capability was observed in 11%, 22%, and 48% of mild, moderate, and severe COVID-19 patients after 12 months of disease onset, respectively. After adjusting for age and sex, severe COVID-19 and the presence of any comorbidity were identified as significant risk aspects for persistently reduced diffusion capability.

Health-related quality of life

Health-related quality of life, including functional status, well-being, and overall health evaluation, was measured at one and 12 months. The age- and sex-adjusted findings revealed that patients with reduced diffusion capability after one month of disease onset exhibited significantly lower physical functioning and general health.

After 12 months of disease onset, no significant difference in health-related quality of life was observed between patients with and without impaired pulmonary functions.

Study significance

A significantly higher prevalence of persistently impaired pulmonary function was observed in patients with moderate or severe COVID-19 as in comparison with patients who’ve recovered from mild COVID-19. Nevertheless, a gradual improvement in pulmonary functions over a period of 12 months was observed in severe COVID-19 patients. 

These findings emphasize the importance of constantly monitoring patients’ health who’ve recovered from severe COVID-19 to effectively manage their long COVID symptoms.