4. DISCUSSION
As a result of this study, we found that 31.2% (n=54) of the patients
who underwent thoracic and abdominal CT scans due to acute fever of
unknown focus were positive for the source of infection. There were
significant differences in age, presence or absence of chronic disease,
and PCT level between the patients with and without an infection source
on CT. We determined that the most important risk factors affecting the
presence of infection on CT were age ≥ 65 years, presence of
comorbidity, and PCT positivity.
Acute fever may be due to the source of infection, as well as various
other causes, including pulmonary embolism, intracranial hemorrhage,
drugs, and malignancy.2 Every person experiences fever
many times in their lives. Most causes of acute fever are related to
viral infections but patients may sometimes unexpectedly face serious
conditions, such as sepsis and septic shock.6 The
detection of the fever focus quickly and accurately with CT scans is
very important for the initiation of appropriate treatment and
survival;4 therefore, the use of CT in ED has
increased in recent years.7 However, CT has certain
disadvantages, such as deterioration in kidney function due to contrast
agent use, exposure to radiation, and additional
costs.8 Therefore, CT imaging should be performed
after careful benefit/risk assessment of the advantages and
disadvantages of this method. In our study, a source of infection was
detected in CT scans in patients with comorbidities, those aged ≥ 65
years, and those with PCT positivity. If clinical benefit is presumed to
be high in these patients, thoracic and abdominal CT scans can be
performed to detect the focus of fever.
Advances in CT technology have allowed this imaging modality to be used
both as a diagnostic and triage method.9 However, this
can raise concerns in terms of the appropriate use of resources. The
reasons for using CT to detect the source of infection in acute febrile
patients without clinical clues in ED are blood parameters, such as WBC,
CRP, and PCT being significantly higher than
normal.10,11 and the need to determine whether there
is an occult focus of infection and decide on hospitalization or
outpatient treatment.12 In a previous study, PCT was
found to be useful in the diagnosis of infection and had a higher
diagnostic value than CRP in patients admitted to ED due to
fever.13 PCT appears to be an earlier and better
marker than inflammatory response parameters, such as CRP and leukocyte
count in sepsis and serious infections.14 From these
data, it can be concluded that clinicians often consider CT scans for
possible infectious disease due to increased inflammatory markers. In
the current study, we found that positive PCT was an effective parameter
in detecting possible sources of infection in CT.
Diseases seen in the geriatric population may show a different course
compared to other age groups and have more dramatic results. In the
elderly, one of the most common causes of hospitalization is infections.
The main reasons for this are the weakening of cellular and humoral
immunity with aging, deterioration of physiological functions, such as
the cough reflex, and comorbidities creating predisposition to
infectious diseases. It may not always be possible to identify
infections without delay in the elderly since they mostly progress with
atypical findings in this population.15 The presence
of fever in the elderly is a more serious indicator of disease compared
to the younger age group. Delayed diagnosis and treatment and more
severe infections increase morbidity and mortality
rates.16 The results of our study indicate that
thoracic and abdominal CT scans should be used more aggressively in
elderly patients with high fever without clinical clues.