To the Editor
The article titled “Evaluation of pulmonary function and exercise capacity after COVID-19 pneumonia” by S Okan et al.1 was thoroughly enjoyed, and the author's diligent work is commendable. Nonetheless, we are obliged to provide some comments on this study's plethora of informative findings to avoid bias in the results.
To ensure valid results, it is crucial to consider whether all participants were treated in the same hospital or recruited from different hospitals and explicitly mention the hospital units, such as ICU or IMD, from which the participants were recruited to assess their varying magnitude of disease severity.2 Moreover, given that the 6-MWT is a more powerful determinant of physical well-being than exercise capacity, using other dependent variables to study the relationship between them and patients' exercise capacity would be more appropriate.3
In addition, measurements other than 6-MWT and pulmonary function should be assessed because they reveal exercise limitations that cannot be evaluated by dyspnea or 6-MWT, as suggested by a similar study.3 The extent of muscle development in patients should be equally monitored to ensure accurate findings, as below 6-MWT results occur due to diminished skeletal muscle strength and muscle atrophy.3
To make the study more comprehensive and inclusive, inflammatory markers that influence individuals' exercise capacity could be used, as shown by a corresponding increase in inflammatory markers with a reduced exercise capacity and vice versa.3 , 4 Additionally, following the convalescence period of covid-19 pneumonia, evaluating parenchymal lung damage in patients using a chest X-ray is essential. The relationship between lung parenchymal damage, tissue consolidations, and covid-19 pneumonia should be further investigated for a more comprehensive and generalized study.5
Lastly, the follow-up results of patients' susceptibility to acute respiratory syndrome coupled with dyspnea following their recovery from covid-19 should be documented, as people with significantly diminished lung function did not suffer from the usual clinical symptoms of dyspnea. However, their quantitative results of essential determinants of lung health were of concern. Thus, relying solely on the common symptoms of dyspnea and 6-MWT values can be deceiving, as these factors significantly impact an individual's exercise capacity.5
Acknowledgment
None.
Declaration of Competing Interest
None.
References
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