Editor:
We appreciated the editorial (1) about our study (2), published in Radiology on February 7, 2023. We thank Dr Vogel-Claussen for his insightful analysis and commentary. He correctly pointed out that abnormal xenon 129 (129Xe) MRI ventilation defect percent (VDP) at 15 months after infection (n = 53; 4.2% ± 6.8 [SD]) may derive from patients with post-acute COVID-19 syndrome who self-identified with prior respiratory disease (n = 22; 7.4% ± 9.1).
Based on his excellent comments, we thought it would be important to dig deeper into the data, so we performed additional analyses on the subgroups with and without prior respiratory disease.
In the subgroup with no self-reported previous lung disease, airways-disease medication at 3 months after COVID-19 infection was associated with a significant and clinically meaningful improvement in the St George Respiratory Questionnaire (SGRQ) score (odds ratio [OR], 3.7; 95% CI: 1.02, 13.14; P = .046) at 15 months compared with 3 months after infection. This was consistent with results in the entire group (OR, 4.0; 95% CI: 1.2, 13.8; P = .03) (2) and the smaller group of participants with prior respiratory illness (OR, 4.5; 95% CI: 0.97, 20.83; P = .05). Therefore, it appears that both subgroups showed an SGRQ improvement, which correlated with airways-disease treatment at 3 months. This finding supports the notion that there is an airways-disease component of post-acute COVID-19 syndrome (3), even in patients with no previous diagnosis of asthma or chronic obstructive pulmonary disease.
In the subgroup without respiratory disease, there was significantly improved forced expiratory volume in 1 second (FEV1; from 89% predicted to 97% predicted; P = .009), ratio of FEV1 to forced vital capacity (from 79% to 84%; P = .008), diffusing capacity of the lungs for carbon monoxide (from 88% predicted to 105% predicted; P = .009), SGRQ score (from 35 to 21; P = .003), and MRI VDP (from 3.2% to 1.5%; P < .001) at 15 months after COVID compared with at 3 months (2). Although trending in a similar versus “the right” direction, there were no significant improvements in participants with self-reported prior respiratory disease (FEV1, from 76% predicted to 82% predicted [P = .6]; diffusing capacity of the lungs for carbon monoxide, from 83% predicted to 92% predicted [P > .99]; SGRQ score, from 37 to 30 [P = .2]; and VDP, from 9.4% to 7.4% [P = .2]).
As Dr Vogel-Claussen (1) appropriately articulated, patients with post-acute COVID-19 syndrome without previous lung disease may be normalizing and improving over time, whereas those with respiratory disease (mainly asthma in this group) may well be improving, but perhaps to a different baseline.
Footnotes
Disclosures of conflicts of interest: H.K.K. No relevant relationships. M.J.M. No relevant relationships. A.M.M. No relevant relationships. S.S. Grants from the Ministry of Health and Long-term Care Ontario, Cyclomedica; consulting fees from Arrowhead Pharma; honoraria for lectures from AstraZeneca, Novartis, Polarean. G.P. Member of Radiology editorial board.
References
- 1. Vogel-Claussen J . Ventilation Defects at 129Xe MRI in Post-acute COVID-19 Syndrome: Back to Normal after 1 year? Radiology 2023. . 10.1148/radiol.230113. Published online February 7, 2023 . [DOI] [PMC free article] [PubMed]
- 2. Kooner HK , McIntosh MJ , Matheson AM , et al . Post-Acute COVID-19 Syndrome: 129Xe MRI Ventilation Defects and Respiratory Outcomes One Year Later . Radiology 2023. . 10.1148/radiol.222557. Published online February 7, 2023 . [DOI] [PMC free article] [PubMed]
- 3. Adeloye D , Elneima O , Daines L , et al . The long-term sequelae of COVID-19: an international consensus on research priorities for patients with pre-existing and new-onset airways disease . Lancet Respir Med 2021. ; 9 ( 12 ): 1467 – 1478 . [DOI] [PMC free article] [PubMed] [Google Scholar]