METHODS
This is a prospective and single-center observational study. The study was conducted in an urban training and research hospital’s emergency department with approximately 150000 patient visits per year. Patients were screened and were included in the study if they were over the age of 18, underwent chemotherapy within the last 7 days due to malignancy and were febrile at the time of presentation. According to Infection Disease Society Of America guidelines, fever is defined as a single oral temperature measurement of >38.3°C or a temperature of >38.0°C sustained over a 1 hour period. Patients were than excluded if they did not have neutropenia. The cases with an Absolute Neutrophil Count (ANC) of 500 cells/mm3 or an ANC that is expected to decrease to 500 cells/mm3 during the next 48 hours have been included in the category of febrile neutropenia [18]. The patients who had another condition that may change oxidative stress parameters(degenerative disease, diabetes mellitus, cardiovascular disease, acute renal failure, cerebrovascular disease, and chronic liver disease apart from the malignancy) were also excluded from the study. Control group included the healthy volunteers.
Written informed consents of both patients and subjects in control group were obtained before their inclusion in the study.
The researchers recorded demographic features (age, gender) chief complaints, medical history of disease and drugs, and signs and symptoms at the time of admission to the emergency department the standardized study forms.
Blood samples were drawn from all patients at the time of admission in order to analyze the blood culture, complete blood count, biochemical markers, thiol/disulphide homeostasis parameters (thiol, disulphide, native thiol, disulphide/native thiol, disulphide/total thiol, native thiol/total thiol), CRP and PCT levels.
After we collected venous blood samples for the measurement of thiol/disulphide homeostasis parameters, centrifuged them at 1500 rpm for ten minutes, and we separated the serum. We stored the serum samples at -80°C until the collection of all samples.Then we sent the serum samples to the biochemistry laboratory at Ataturk Training and Research Hospital, Ankara, Turkey subsequent to the completion of the sample collection process.
The laboratory staff measured the native thiol and total thiol by means of a new and fully automatic system, and they calculated the disulphide and ratios of disulphide/native thiol, disulphide/total thiol and native thiol/total thiol [10]. PCT (Roche Cobas 6000 Japan) and CRP (Siemens BNII, Germany) were also measured in the same laboratory.
MASCC risk scores (Table 1) of the patients were calculated at the time of admission. Patients whose MASCC score was ≥ 21 points were classified as a low-risk group while the patients that have MASCC score < 21 points were categorized as a high-risk group [18,19]. The patient group was compared with the control group in terms of thiol, disulphide, disulphide/native thiol, disulphide/ total thiol, native thiol/total thiol, CRP and PCT values. Moreover, the patient group was divided sub-groups: patients who had mortality within 28 days and patients who survived over 28 days, high-risk patients and low-risk patients according to MASCC scores and the patients who had a positive or a negative blood culture. These groups were compared to each other in terms of thiol, disulphide, disulphide/native thiol, disulphide/total thiol, native thiol/total thiol, CRP and PCT values.
The results were presented as mean ± SD. Univariate statistical analyses were performed by using a chi-square test for categorical variables and Student-t-test for continuous variables. P <0.05 was accepted to be statistically significant.