Small Airway Disease as long-term Sequela of COVID-19: Use of Expiratory CT despite Improvement in Pulmonary Function test

  1. Alpana Garg
  2. Prashant Nagpal
  3. Sachin Goyal
  4. Alejandro P. Comellas

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Abstract

Background

It is important to understand the spectrum of pulmonary diseases that patients are presenting after recovery from initial SARS-CoV-2 infection. We aim to study small airway disease and changes in Computed Tomography (CT)and pulmonary function tests (PFTs) with time.

Methods

This is retrospective observation study including adult patients with confirmed SARS-CoV-2 infection with at-least two CT scans either during acute (defined as <1 month) or subacute (1-3 months) or chronic (>3months) phase after positive test. Radiological features and follow up PFTs were obtained.

Results

22 patients met the inclusion criteria with mean age 57.6 years (range 36-83). Out of these,18 (81.81%) were hospitalized. Mean duration of diagnosis to CT and PFT was 192.68(112-385) days and 161.54(31-259) days respectively. On PFTs, restrictive pulmonary physiology was predominant finding during subacute 56.25% (9/16) and chronic phases 47% (7/15). PFTs improved significantly with time {FEV1((p=0.0361), FVC (p=0.0341), FEF 25%-75% (p=0.0259) and DLCO (p=0.0019)}, but there was persistent air trapping in the expiratory chronic phase CT. There was resolution of ground glass opacity, consolidation, and bronchiectasis however air trapping increased with time in 41.61% (10/21) of subacute CTs compared to 81.25% (13/16) in chronic CTs.

Conclusion

Our study shows evidence of airway as well as parenchymal disease as relatively long-term sequel of SARS-CoV-2 infection. It also highlights the natural course and spontaneous recovery of some radiological and pulmonary function test abnormalities over time with evidence of persistent small airway disease (air trapping) on expiratory CT imaging months after infection.

Highlights

  • Long term pulmonary complication of SARS-CoV-2 infection include small airway disease

  • There is role of inspiratory and expiratory Computed tomography (CT) scan to identify air trapping in patients with persistent respiratory symptoms after SARS-CoV-2 infection

  • Normal spirometry and normal routine CT may not be sufficient to characterize and identify cause of persistent respiratory complains in patients after COVID-19

  • This study highlights persistent parenchymal and physiological airway abnormalities more than six months after recovery from initial SARS-CoV-2 infection

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    1. ScreenIT

      SciScore for 10.1101/2021.10.19.21265028: (What is this?)

      Please note, not all rigor criteria are appropriate for all manuscripts.

      Table 1: Rigor

      EthicsIACUC: The study was approved by Institutional board review (IRB# 2020055421).
      Consent: Written informed consent was obtained from all the patients included in the study.
      Sex as a biological variablenot detected.
      Randomizationnot detected.
      Blindingnot detected.
      Power Analysisnot detected.

      Table 2: Resources

      No key resources detected.

      Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

      Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
      Our study had certain limitations. It is a single center, observational study which included relatively small number of symptomatic patients. However, since COVID-19 is a relatively new disease our aim was to include patients with comparable follow-up. Due to retrospective design, not all the patients were followed at the same regular intervals. Hence, there are some missing data points (not all the patients had imaging or PFT in all phases [acute, subacute, and chronic]). We cannot correlate the findings with underlying co-morbidities and clinical course as the sample size is small. Due to heterogeneous cohort, it will be difficult to determine which patients are more prone to developing small airway disease based on their clinical characteristics and illness course during acute infection. More longitudinal follow up studies including large number of patients can be done in future to delineate the risk factors and prevalence of fSAD in patients after SARS-CoV-2 infection. Also, studies are needed to understand the long-term consequences and treatment modalities in patients presenting with differing clinical and radiological phenotypes.

      Results from TrialIdentifier: No clinical trial numbers were referenced.

      Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

      Results from JetFighter: We did not find any issues relating to colormaps.

      Results from rtransparent:
      • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
      • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
      • No protocol registration statement was detected.

      Results from scite Reference Check: We found no unreliable references.

      About SciScore

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    2. Version published to 10.1101/2021.10.19.21265028v1 on medRxiv