Discussion
Previously, many symptoms such as fatigue, respiratory dysfunction,
exercise intolerance, psychiatric disturbances, and weakness had been
experienced by studied patients after the severe acute respiratory
syndrome (SARS) attack in 2003.[ 6,7] A meta‐analysis of 28
longitudinal studies reported that 25% of SARS and Middle East
respiratory syndrome coronavirus infected patients had reduced lung
function and exercise capacity at 6 months following discharge from the
hospital.[8]
A review of available evidence on patients with COVID-19 infection
suggested that post-acute COVID-19 recovery may be not complete. This
evidence indicates that even those classified as mild infection continue
to have persistent symptoms that overlap considerably with those
recovering from more severe infection. However, the natural history,
prevalence, causes, and predictors of these symptoms remain
obscure.[3]
Descriptive clinical follow-up study of 150 patients showed that two
thirds of adults with noncritical COVID-19 had complaints, in particular
smell disturbances, shortness of breath or asthenia, up to 60 day after
symptoms onset.[2]Aa recent study from Italy has found that about
87% patients who were discharged from the hospital after recovery from
COVID-19 showed persistent symptoms , particularly shortness of breath
and fatigue.[9] Persistent shortness of breath and cough may be
attributed to pulmonary cellular damage and increased cough reflex
sensitivity. Whether there is cardiac contribution to post-acute
persistent symptoms requires further interrogation. [10]
The association of high Hb at presentation with persistent fatigue and
high PMV with complete recovery in our study deserve appropriate
consideration. The nucleic acid of coronavirus might be closely related
to abnormal hemoglobin metabolism in humans. The coronavirus attacked
the beta chain of hemoglobin leading to toxic and inflammatory state in
the tissues. Heme linked sites of coronavirus protein may be relevant to
the high infectivity related to the virus replication Thus, the higher
the hemoglobin level, the higher the risk of covid-19 disease infection
and burden.[11]
In patients with chronic fatigue syndrome, it has been reported that RBC
are larger and less deformable than those of healthy control leading to
impaired microvascular perfusion and tissue oxygenation. [12].
Of note, MVP, as a marker of variation in platelet size and age, is
reported to be a potential indicator of platelet function and
activation.[13] increased MPV may suggest that these platelets may
present in hyperactive state. Higher platelet turnover is associated
with considerable change in platelets size and release of young
platelets, which are functionally more active and have higher volumes
than older platelets. Given this association high PMV with increased
production of young and active platelets, It can speculated that PMV may
represent a marker of the capacity of the bone marrow to compensate for
platelet turnover during acute phase of viral infection.
Conclusion, mild lung injury and high PMV were predictors for complete
recovery. Low Hb at presentation, length of ICU stay, extensive lung
injury, shortness of breath at presentation, and old age were predictors
for persistent shortness of breath, while high Hb, extensive lung
injury, and productive cough at presentation were predictors for
persistent fatigue. A long-term follow up study is required for better
understanding of the progression of post‐acute COVID‐19 persistent
symptoms.
Funding: There were no external funding sources for this study.
Conflict of Interest: The authors declare that they have no
conflict of interest.