Changes in pulmonary function and patient-reported outcomes during COVID-19 recovery: a longitudinal, prospective cohort study

OBJECTIVES: The aim of this study was to compare respiratory and patient-reported outcome measures (PROMs) between 3 and 6 months after symptom onset and to identify features that predict these changes. METHODS: This was a consecutive prospective cohort of 73 patients who were hospitalised with coronavirus disease 2019 (COVID-19). We evaluated the changes in pulmonary function tests and PROMs between 3 and 6 months and then investigated the associations between outcomes (change in diffusing capacity of the lung for carbon monoxide (D(LCO)), dyspnoea and quality of life (QoL)) and clinical and radiological features. RESULTS: There was improvement in forced vital capacity, total lung capacity and D(LCO) between 3 and 6 months by 3.25%, 3.82% and 5.69%, respectively; however, there was no difference in PROMs. Reticulation and total computed tomography (CT) scores were associated with lower D(LCO) % predicted at 6 months (coefficients; −8.7 and −5.3, respectively). The association between radiological scores and D(LCO) were modified by time, with the degree of association between ground glass and D(LCO) having decreased markedly over time. There was no association between other predictors and change in dyspnoea or QoL over time. CONCLUSIONS: There is improvement in pulmonary function measurements between 3 and 6 months after COVID-19 symptom onset; however, PROMs did not improve. A higher reticulation and total CT score are negatively associated with D(LCO), but this association is attenuated over time. Lastly, there is a considerable proportion of patients with unexplained dyspnoea at 6 months, motivating further research to identify the underlying mechanisms.