DISCUSSION
Our study included 271 patients aged 18–65 years with positive RT-PCR
tests for COVID-19 who had symptoms for longer than 5 days at the time
of admission. Smoking and the presence of HT were found to be
statistically significant in the group that developed pneumonia.
Hospitalisation, the need for additional antibiotics, desaturation and
bilateral involvement of the lung parenchyma were more common in the
pneumonia group. Of the laboratory parameters, initial D-dimer,
troponin, neutrophil, NLR, CRP, LDH and ferritin levels were higher in
the pneumonia group, and lymphocyte, albumin and haemoglobin values were
lower. Older age, presence of HT, dyspnea at hospital admission, low
albumin and high troponin were found to be risk factors for the
development of pneumonia. Studies have shown that the need for
mechanical ventilators, intensive care hospitalisation and death rates
are significantly higher in COVID-19 patients over 65 years of age
compared to younger patients (6, 7). However, no specific data for the
clinical features and treatment of young adult COVID-19 patients
admitted to hospitals have been published. As far as we know, although
studies on COVID-19 patients under the age of 65 have been published, no
comparative studies between young adult patients with and without
pneumonia have been published. In a study of patients under the age of
50 with a diagnosis of COVID-19, 56% of the patients were male, their
mean age was 44.44 years, and 92.1% had CT lung involvement (3). Our
study found that pneumonia developed at a rate of 67.9%, with a mean
age of 46.48 ± 11.99 years. In another study, where a median age of 50
years (IQR; 40–68) was found in a pneumonia group, it was stated that
older age was a significant risk factor for the development of pneumonia
(8). In Jung et al.’s (9) study, the mean age of a group of patients who
initially developed pneumonia or during a follow-up was significantly
higher (51.5 and 54.9 years, respectively) compared to a group without
pneumonia (38.5 years). In our study, in accordance with the literature,
the median age was 51 years (IQR; 41.5–58) in the group that developed
pneumonia, and older age was statistically significant for the
development of pneumonia. In the literature, it has been stated that HT,
CVD, DM and smoking are associated with poor clinical outcomes of
COVID-19 cases (10, 11). In our study, the most common comorbidities
detected in the pneumonia group were HT, DM and CVD, and there was a
significant relationship between smoking and the development of
pneumonia. The most commonly reported symptoms observed in COVID-19
patients are fever, cough and myalgia (12, 13). In our study, these
symptoms were common in the pneumonia group, but only dyspnea was
statistically significantly associated with COVID-19 pneumonia. Fever,
the most common COVID-19, was not found to be significant in our study,
suggesting that it was not a predictor for pneumonia. In another study,
approximately 63% of hospitalised COVID-19 patients under the age of 65
had desaturation, and the hospital stay was longer in this group (14).
In our study, desaturation and hospitalisation were statistically more
significant in the pneumonia group. To date, most studies on prognostic
markers have shown an increase in D-dimer and LDH values and a decrease
in lymphocyte levels (15, 16), and Zhang et al. (17) emphasised that
D-dimer levels are an important marker for determining mortality in
cases with COVID-19 pneumonia. Itelman et al. (18) emphasised that
patients with severe COVID-19 have higher leukocyte and neutrophil
counts and LDH levels. In our study, increased D-dimer and LDH and
decreased lymphocyte levels were found to be statistically significantly
higher in the pneumonia group. NLR, high CRP and low albumin have high
sensitivity and specificity for demonstrating inflammation. Studies have
shown that the NLR and the CRP/lymphocyte ratio are independent
prognostic markers for many diseases (19, 20). In our study, while the
NLR and initial CRP values were high in patients with pneumonia, albumin
and lymphocyte values were lower. In a retrospective cohort study
involving 191 patients with COVID-19 from Wuhan, China, high LDH and
ferritin levels were associated with mortality (21), and Wang et al.
(22) reported that 40% of patients with COVID-19 had high LDH values at
the time of admission. In a systematic review conducted by Taneri (23),
including 189 studies and 57,563 patients, compared to patients with
intermediate or low risk of disease, high ferritin and low haemoglobin
levels were found in patients with high risk for severe disease (23).
Cobre et al. (24) also found that high ferritin and low haemoglobin
levels were observed in both COVID-19 patient groups and patients with
severe disease (24). In our study, while haemoglobin levels were lower
in the group that developed pneumonia, ferritin and LDH levels were
higher. In a systematic review of four studies, including 374 patients,
troponin levels were observed to be significantly higher in patients
with severe COVID-19 infection compared to non-serious patients (25).
Zhu et al.’s (15) study also found that troponin values were a
prognostic marker for severe disease. In our study, troponin values were
higher in the group with pneumonia, and they were found to be a
statistically significant risk factor for the development of pneumonia.
In various studies, increased liver function markers, particularly ALT,
AST, gamma-glutamyl transferase and total bilirubin levels, have been
described in COVID-19 patients (26, 27). However, no statistical
difference was found in these values in our study. In one study, at the
time of diagnosis, 203 patients had bilateral pneumonia, 39 patients had
unilateral pneumonia, 6 patients had normal thorax CT scan results and
163 (65.7%) had radiological progression of symptoms on the 7th day in
repeated radiological imaging (28). In another study, patients with or
without pneumonia at the time of diagnosis had negative or positive CT
findings according to the duration of symptoms; it was stated that the
presence of pneumonia varied depending on the time after symptom onset,
and the non-pneumonia group was characterised by younger patients,
normal laboratory findings, and less comorbidity (9). In another study,
it was stated that positive CT findings were associated with symptom
duration, and 56% of patients showed normal CT findings in the early
phase (0–2 days) after symptom onset (29). Patients with symptoms for
more than 5 days were included in our study, and in accordance with the
literature (30), bilateral involvement was more common in the group with
pneumonia, and older age was considered a risk factor for the
development of pneumonia.