Pulmonary Function After COVID-19: Preliminary Results of Survivorship Registry at 1 Month, 3 Months, and 6 Months

Abstract

RATIONALE: Survivors of the first SARS epidemic had impaired exercise capacity and lung function remain at six months after illness.1 Due to the novel nature of SARS-CoV-2, practitioners can only extrapolate from prior coronavirus pandemics when anticipating sequelae of COVID-19. This study seeks to help draw conclusions about long-term outcome in survivors of COVID-19. METHODS: Patients over 18 with confirmed COVID-19 are prospectively enrolled to a registry which collects clinical, serologic, functional, and radiographic data at one month, three months, six months, and twelve months post recovery from acute infection, as determined by symptoms (outpatients) or hospital discharge (inpatients). Complete pulmonary function tests (PFT) and 6 minute walk distances (6MWD) are collected at each time point. RESULTS: All currently completed PFT and 6MWD data were included in analysis (PFT: 1 month, n=16;3 months, n=26;6 months, n=25;6MWD: 1 month, n=14;3 months, n= 17;6 months, n=21). Mean 6MWD was 350m at 1 month, 362m at 3 months, and 373m at 6 months. At 1 month, 56% had normal spirometry;38% had restriction and 6% had mixed obstructive/restrictive pattern. At 3 months, 50% had normal spirometry with 42% showing restriction, 4% obstruction, and 4% mixed pattern. By 6 months, 64% had normal spirometry, 24% had restriction, and 12% had obstruction. There was diffusion limitation in 50% at both 1 month and 3 months;by 6 months, this improved to 32%. At one month, subjects older than 65 had significantly lower DLCO when compared those younger than 40 (10.54 vs 24.07 ml/min/mmHg, p<0.001) and when compared those aged 40-64 (10.54 vs 18.58 ml/min/mmHg, p<0.01);this change persisted at six months (13.67 vs 20.7 ml/min/mmHg, p<0.05). When stratified by clinical illness severity, or weight, there was no significant difference seen across PFT variables. 6MWD did not show significant difference when stratified by age, weight, or illness severity. CONCLUSIONS: In survivors of COVID-19, there are persistent functional and clinical sequelae up to six months post-recovery. Functional capacity remains impaired at six months. Predominant spirometric abnormality is restriction, which improves over time. Importantly, DLCO remains low in half of the subjects at both one and three months, with some improvement by 6 months. The diffusion impairment is significantly worse in patients older than 65. More investigation is required to elucidate the etiology of ongoing diffusion limitation and correlate with ventilation/perfusion studies.