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Long-term lung function trajectories in Swedish COVID-19 ICU survivors: a two-year follow-up study
Marta A Kisiel1, Emil Ekbom2, Christer Janson2
1Department of Medical Sciences, Occupational and Environmental Medicine, Uppsala University, Uppsala, Sweden.
Insights
Two years after critical COVID-19, one-third of patients still had impaired diffusing capacity for carbon monoxide (DLco). This highlights the need for pulmonary follow-up to address persistent lung function deficits.
Area of Science:
- Pulmonology
- Critical Care Medicine
- Infectious Diseases
Background:
- Longitudinal studies on COVID-19 lung function post-intensive care unit (ICU) admission are limited.
- Understanding long-term respiratory sequelae is crucial for patient management.
Purpose of the Study:
- To investigate lung function in COVID-19 survivors for two years after ICU discharge.
- To identify factors associated with impaired diffusing capacity for carbon monoxide (DLco).
Main Methods:
- A cohort of COVID-19 patients admitted to Uppsala ICU were followed for two years post-discharge.
- Lung function was assessed using spirometry, diffusing capacity for carbon monoxide (DLco), and body plethysmography at four months, one year, and two years.
- Logistic regression was used to analyze associations between impaired DLco and patient characteristics, adjusted for age, sex, and BMI.
Main Results:
- Impaired DLco was present in 50% at 4 months, 58% at 1 year, and 33% at 2 years.
- DLco% predicted declined from 4 months to 1 year but improved significantly between 1 and 2 years.
- Forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) also showed improvement over time.
- Impaired DLco at 4 months was linked to older age, mechanical ventilation, longer ICU stay, lower lymphocyte count, and reduced FVC/FEV1.
Conclusions:
- Despite recovery, a significant proportion of patients have persistent DLco impairment two years post-critical COVID-19.
- Pulmonary follow-up is essential to manage long-term lung function deficits in these patients.
Introduction:
Longitudinal studies of lung function following COVID-19 remain limited. This study examined lung function in COVID-19 patients for two years after discharge from an intensive care unit (ICU).
Methods:
Patients treated for COVID-19 in Uppsala ICU (mean 11.1 days) were assessed at four months, one year, and two years post-discharge. Lung function tests included spirometry, diffusing capacity for carbon monoxide (DLco), and body plethysmography. Logistic regression adjusted for age, sex, and body mass index (BMI) assessed the association between impaired DLco and patients' characteristics.
Result:
A total of 104 patients (32% female, with a mean age of 60 years) participated in four months follow-up, 40 in one year follow-up, and 21 in two years follow-up after discharge. Impaired DLco was observed in 50%, 58%, and 33% of patients at four months, one year, and two years, respectively. A comparison showed that DLco% predicted declined from four months to one year (mean 79.0, SD 14.7, to 74.3, SD 15.7; p< 0.001), then improved between one and two years (p< 0.001). Forced vital capacity (FVC) % predicted improved between four months and one year (p < 0.001) and between one and two years (p = 0.004). Forced expiratory volume during the first second (FEV1) % predicted improved only between four months and one year (p = 0.002). Total lung capacity improved between the one- and two-year follow-ups (p = 0.006). Impaired DLco at four months was significantly associated with age ≥60 years (adjusted odds ratios, 95% confidence interval: 6.73 (2.64-17.12), mechanical ventilation (4.74 (1.82-12.34), longer ICU stay (5.84 (2.13-16.01), minimum lymphocyte count at ICU (0.19 (0.04-0.83), and FVC % predicted (0.93 (0.89-0.96)) and FEV1 % predicted (0.93 (0.89-0.97)).
Conclusion:
Despite recovery between one and two years, one-third of patients exhibited impaired DLco two years after critical COVID-19, highlighting the need for pulmonary follow-up to address persistent lung function deficits.
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