4 DISCUSSION
In this study, the comparison of CSD and cancer examined as
comorbidities in patients with COVID-19 was investigated for the first
time in the literature to the best of our knowledge. It was observed
that patients with CSD and/or cancer were at higher risk in terms of
intensive care admission, intubation, rate of complications and survival
compared to patients without comorbidities. In addition, there was no
significant difference in clinical parameters and survival between those
with cancer and those with CSD, except that Hb and ferritin levels were
significantly different in those with cancer.
In a large COVID-19 clinical study conducted in China, the mean age of
participants was 47 years, and 58% of the participants were
male.8 However, in our study, the mean age was lower,
and the proportion of males was almost similar. The absence of patients
under the age of 18 years may be the main reason for the mean age
difference in our participants. In addition, the mean age of patients
with CSD and cancer was higher than that of patients without
comorbidities. This situation can be explained by the higher prevalence
of CSD in older patients.9 The most common symptoms in
the patients in our study were cough, fever and myalgia, which was
similar to the results reported in the literature.10In a meta-analysis examining the prevalence of comorbidities, the most
frequently reported ones were hypertension and
diabetes.11 Similarly, the most common CSDs in the
patients in our study were diseases related to the cardiovascular and
endocrinological systems. Evaluation of hypertension under the title of
cardiovascular system diseases and diabetes under the title of
endocrinological system diseases could have had an effect on this
result.
CRP is an acute phase reactant induced by interleukin (IL)-6 produced by
the liver and is a sensitive biomarker in various inflammatory
conditions such as infection and tissue damage.12 An
increase in serum CRP levels has been observed in many studies as a
reliable indicator of the presence and severity of SARS-CoV-2
infection.13,14 Damage to any of the multiple cell
types containing LDH results in increased serum LDH levels. Therefore,
elevated LDH is common in critically ill patients with COVID-19 and is
believed to indicate poor prognosis.12 D-dimer is
another important biomarker investigated as a potential prognostic
factor of disease severity in COVID-19. It was found that compared to
patients with D-dimer levels of <2.0 μg/mL, those with higher
D-dimer levels had a higher incidence of comorbidities such as diabetes,
hypertension, coronary artery disease and stroke.15 In
our study, CRP, LDH and D-dimer levels were significantly higher in and
patients with CSD and cancer compared to those without comorbidities.
NLR has been used as a prognostic indicator for conditions such as
acute-on-chronic hepatitis B liver failure16 and as a
mortality risk factor for malignancy, acute coronary syndrome and
cerebral haemorrhage.17,18,19 Recent studies suggest
that NLR is an early predictor of critical illness in SARS-CoV-2
infection.20 It is reported that patients with severe
COVID-19 have higher neutrophil count and lower lymphocyte count
compared to nonsevere patients, and therefore, NLR tends to be higher in
patients with severe infection.21 This explains why
NLR was significantly higher in patients with cancer and CSD along with
COVID-19 compared to patients with COVID-19 without comorbidities in our
study.
Patients with CSD who are also infected with SARS-CoV-2 require more
medical attention, such as intensive care admission and mechanical
ventilation therapy.22 Similarly, patients with cancer
have a higher incidence of intensive care admission, mechanical
ventilation and complications.23,24 In our study, the
rate of referral to the intensive care unit exceeded 20% in patients
with cancer and CSD, whereas this rate was 5% in patients without
comorbidities. Whereas 25% of the patients admitted to the intensive
care unit without comorbidities required intubation, this rate exceeded
50% in those with CSD and cancer. Similar to the literature, in our
study, intensive care admission and need for mechanical ventilation in
patients with CSD and cancer were clinically significantly higher.
However, there was no significant difference between patients with CSD
and those with cancer. It is observed that the benignity or malignancy
of the comorbid chronic processes does not have a significant effect on
the COVID-19 clinical picture; this information is contributed to the
literature for the first time in this study.
The survival rates of those with CSD and cancer were significantly lower
than those without comorbidities. It was not surprising that the
mortality rates were high (33.3%) in the group with both cancer and CSD
(Group 4). Similar to the results reported in many studies, the presence
of CSD and cancer was associated with mortality in our
study.25,26
In a meta-analysis, it was demonstrated that patients with severe
COVID-19 had lower Hb levels than those with moderately severe COVID-19.
This suggests that the severity and prognosis of the disease in patients
with COVID-19 may be associated with lower Hb
levels.27 Patients with anaemia have a higher
prevalence of comorbidities such as hypertension, cardiovascular disease
or chronic kidney disease, all of which are known risk factors for
COVID-19-related death.2 Ferritin not only has a role
in iron storage, but also is a well-known acute phase
reactant.28 Ferritin H chain may be important in
activating macrophages to increase the secretion of inflammatory
cytokines observed in patients with COVID-19. The clinical picture in
critical patients with COVID-19 resembles that of those with macrophage
activating syndrome, which is often associated with high levels of
ferritin and cytokine storms.29 In our study, unlike
other parameters, there was a clinically significant difference only in
high ferritin and low Hb levels between patients with CSD and those with
cancer. Patients with cancer were significantly different from patients
of other groups in this regard. One of the most important factors for
this difference may be that the release of inflammatory cytokines is
higher in patients with cancer than in those with other CSDs. In
addition, the grouping of haematological cancers under the title of
cancer and higher frequency of anaemia in these patients may be another
factor.
This study has some limitations. The number of samples was not
homogeneously distributed among the groups. As the study was
retrospective, the severity of comorbidities and compliance of patients
with medical prescriptions could not be evaluated. It is known that some
metabolic variables can reach pathological values in COVID-19 as well as
some chronic inflammatory processes. Since there are no subjects without
COVID-19 among our participants, it cannot be demonstrated to what
extent COVID-19 affects the current values of these measurements.