One-Fourth of COVID-19 Patients Have an Impaired Pulmonary Function after 12 Months of Illness Onset

Background: This longitudinal study evaluates the extent of impaired pulmonary function over time after SARS-CoV-2 infection across the full spectrum of COVID-19 severity.Methods: Pulmonary function was measured by diffusing capacity for carbon monoxide (DLCO) at one, six, and twelve months after illness onset. Additionally, data on sociodemographics, clinical characteristics, symptoms, and health-related quality of life (HRQL) were collected. Pulmonary function and determinants were modelled over time using mixed-effect linear regression. Determinants of pulmonary impairment at 12 months since illness onset were identified using logistic regression.Findings: Between May 2020 and December 2021, 301 of 349 participants underwent at least one pulmonary function test. After one year of follow-up, 25% of the participants had an impaired pulmonary function which translates in 11%, 22%, and 48% of the participants with mild, moderate and severe/critical COVID-19. Improvement in DLCO among the participants continued over the period across one, six and twelve months. Having more than three comorbidities (p<0·001) and initial severe/critical illness (p<0·001) were associated with slower improvement of pulmonary function over time, adjusted for age and sex. HRQL improved over time and was not different to those without impaired pulmonary function.Interpretation: The prevalence of impaired pulmonary function after twelve months of follow-up, was still significant among those with initially moderate or severe/critical COVID-19. However, those who continued to have impaired pulmonary function after one year did not have impaired HRQL.Funding: This work was supported by the Netherlands Organization for Health Research and Development (ZonMw) [10150062010002 to M.D.d.J.] and the Public Health Service of Amsterdam [R&D in 2021 and 2022 to M.P.].Declaration of Interest: All authors declare no competing interests.Ethical Approval: Written informed consent was obtained from each study participant. The study design was approved by the local ethics committee of the Amsterdam UMC (Medisch Ethische Toetsingscommissie [METC]; NL73759.018.20).