Jun 12, 2015 - Hemorrhagic manifestations vary from petechia to ecchymosis, epistaxis, melena etc. which are detected in severe cases 3-6 days after the ...
Advance Publication by J-STAGE Japanese Journal of Infectious Diseases
Prognostic factors in Crimean-Congo hemorrhagic fever and the effect of leukocyte counts on mortality
Aliye Bastug, Bircan Kayaaslan, Sumeyye Kazancioglu, Halide Aslaner, Ayse But, Esragul Akinci, Meltem Arzu Yetkin, Selim Eren, and Hurrem Bodur
Received: December 10, 2014. Accepted: April 6, 2015 Published online: June 12, 2015 DOI: 10.7883/yoken.JJID.2014.566
Advance Publication articles have been accepted by JJID but have not been copyedited or formatted for publication.
Prognostic factors in Crimean-Congo hemorrhagic fever and the effect of leukocyte counts on mortality
Aliye Bastug, MD, Bircan Kayaaslan, MD, Sumeyye Kazancioglu, MD, Halide Aslaner, MD,
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Ayse But, MD, Esragul Akinci, Prof., Meltem Arzu Yetkin, Associated Prof., Selim Eren,
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MD, Hurrem Bodur, Prof.
Ankara Numune Training and Research Hospital Department of Infectious Diseases and Clinical Microbiology
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Running Headline: The effect of leukocyte counts on mortality in CCHF
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Corresponding author: Aliye Bastug
Adress: Ankara Numune Training and Research Hospital Department of Infectious Diseases and Clinical Microbiology
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Anafartalar Mh., Talatpaşa Bulvarı No:5, post code: 06030 Altındağ/Ankara
E mail: dr.aliye@ yahoo.com Telephone Number: +9 05056814223 Fax number: +9 0312 5084838 Keywords: Crimean-Congo hemorrhagic fever: CCHF, vector-borne, mortality risk factors
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Summary Crimean-Congo hemorrhagic fever is a life threatening illness. We aimed to detect the effect of the leukocyte counts on survival. This is the first study analyzing the relationship between
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mortality and leukocyte counts. A total of 220 patients were evaluated retrospectively. The
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mortality rate was found 16.4%. The analysis of relationship between leukocyte counts and mortality rates showed us some important clues for pathogenesis. ROC curve analysis revealed that if the leukocyte counts on admission were ≥ 2950/mm3, mortality rate could be predicted with 62.1% sensitivity. In consideration of the mean hospitalization length in fatal
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cases (4.3 days), third-admission day leukocyte counts were compared. Increase of the neutrophils and decrease of the lymphocytes and monocytes were found as significant risk factors for mortality (p = 0.01, p = 0.037, p = 0.001). The mortality risk was found 8-12 folds higher in patients with upper levels of cut- off for leukocytes (2950 µl), LDH (967 U/L) and
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aPTT (42.4 s), ALT (>119.5 u /l) which were determined as an independent predictors of mortality. The depletion of monocytes, lymphocytes and the increase of neutrophil counts were correlated with poor outcome. These results suggest the importance of mononuclear
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immune response for survival in CCHF.
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Introduction
Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic viral disease caused by CCHF virus (CCHFV) which belongs to Nairovirus genus in the Bunyaviridae family (1). Hyalomma ticks are the main vectors of the disease. CCHFV can also be transmitted by blood or body secretions of viremic patients and livestock. The disease is widespread throughout Africa, Central Asia, Southeast Europe and the Middle East (2 –5). CCHF has been reported in Turkey since 2002 and it has been an important public health threat due to the high mortality
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rate especially in rural areas (3, 6, 7). Mortality rate is different, ranging between 5 to 30% depending upon the geographic regions and transmission routes (8, 9). Incubation period ranges from 3 to 7 days according to the titer of virus and routes of transmission (8, 10). Fever, chills, myalgia, severe headache, dizziness, nausea, vomiting, diarrhea and abdominal pain are nonspecific symptoms of CCHF. Hemorrhagic manifestations vary from petechia to
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ecchymosis, epistaxis, melena etc. which are detected in severe cases 3-6 days after the onset of the disease (10). There was no specific antiviral treatment which has a proven effect for CCHF. Supportive treatment was suggested in the literature (11, 12). Epidemiologic features, pathogenesis, clinical characteristics and severity criteria were reported in different studies (2, 8, 13, 14). In this study we aimed to detect the effect of leukocyte, neutrophil, lymphocyte
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and monocyte levels on survival. To our knowledge this is the first study analyzing the relationship between leukocyte types and mortality. Materials and Methods
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Study design, setting and patients
This retrospective case control study was carried out at Ankara Numune Education and Research tertiary care Hospital (ANERH) in Turkey. The medical records of patients who had
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been followed with the CCHF diagnosis in the hospital between 2002 -2013 were investigated.
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Patients with a decisive diagnosis of CCHF via clinical manifestations and the positive results of viral RNA by reverse transcriptase - polymerase chain reaction (RT-PCR) and/or specific IgM antibody were enrolled to the study. Demographical, clinical and laboratory characteristics and outcomes of the patients were recorded. First and third admission-days leukocyte, lymphocyte, neutrophil and monocyte levels of the patients were compared between fatal and nonfatal cases to determine the impact on mortality. Beckman Coulter LH 750 Hematology Analyzer was used in laboratory. Our study doesn't require informed consent
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from patients and an approval from the Ethics Committee which was not necessary since it is a retrospective trial. Statistical analysis Statistical analysis was performed by SPSS 20.0 for Windows program. Descriptive statistics
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were represented as mean, standard deviation, median, minimum and maximum for
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quantitative variables; as number and percentage for categorical variables. In numerical comparisons, when normal distribution was provided T-Test was used for paired independent groups; when normal distribution was not provided Mann Whitney U test was used for paired independent groups. In numerical comparisons, when normal distribution was provided Paired
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T-Test was used for paired dependent groups; when normal distribution was not provided Wilcoxon Signed Rank test was used. In categorical comparisons, Chi-square test and Fisher’s exact test were used for paired groups’ comparisons. ROC Analysis was used to determine cut-off-values. Logistic regression analysis was used in the determination of risk
Results
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factors for categorical variables. Statistical level of significance was set at p < 0.05.
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The mean age of total 220 patients was 50.21 ± 17.07 years (range, 15-85) and 55.9% (n =123) were male. The mortality rate was 16.4% (n = 36). One hundred seventy one patients
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(77%) were living in a rural area and 165 patients (75%) were dealing with livestock. May, June and July were the most frequent months in which 85.9% (n = 189) of the patients were admitted to the hospital. A tick bite history was defined in 140 (63.6%) patients. The mean incubation period after tick bite history was found as 3.8 ± 3.0 days. The most frequent symptoms of the patients were fever (88.2%), lack of appetite (79.1%) and myalgia (75%). Sixty five (29.5%) patients had hemorrhage and twenty five (11.4%) had somnolence. Age, gender, co morbidities (diabetes mellitus, hypertension and chronic obstructive pulmonary
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disease), incubation period and length of the symptoms before admission were not statistically different between fatal and non-fatal groups (Table 1). Ribavirin treatment was not given to any of the patients. Only supportive treatment was applied to all of the patients. The mean length of hospitalization was 6.42 ± 3.06 days which was significantly shorter in fatal cases (p < 0.001). When fatal and non fatal cases were compared with univariate analysis;
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leukocytosis (11.1%), hemorrhage (66.7 %), somnolence (47.2%), melena (41.7%), ecchymosis (38.9%), petechia (36.1%), gum bleeding (30.6%), hematuria (22.2%),
haematemesis (19.4%), hemoptysis (11.1%), hematoma (8.3%) and infusions requirements (i.e. fresh frozen plasma, platelets and erythrocyte infusions) were significantly on higher rates in fatal cases (p < 0.001) (Table 1 and Table 2). Fatal patients had significantly higher
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rates of elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine phosphokinase (CPK), and thrombocytopenia on the firstadmission day (p < 0.001). Median values of laboratory parameters were summarized in
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Table 2.
In the comparison of the first admission-day laboratory values between fatal and non-fatal cases; white blood cells (WBC) and neutrophil levels were found significantly higher in fatal
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cases by univariate analysis (p = 0.006, p = 0.001, respectively). When the third admission day leukocyte counts were evaluated; higher neutrophil levels (p = 0.01) and lower
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lymphocyte and monocyte levels were statistically significant in fatal cases by univariate analysis (p = 0.037, p = 0.001 respectively) (Table 3). As compared with the first and third admission-day laboratory values by univariate analysis, increase of leukocyte, lymphocyte and monocyte levels were statistically significant in non-fatal cases (p < 0.001 for all of them). However, there was no significant difference in fatal cases (Table 4). Cut off levels of the first admission-day laboratory parameters as a prognostic factor for predicting mortality were determined and summarized in Table 5.
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ROC curve analysis revealed that if the WBC count was ≥ 2950/mm3 on admission day, mortality rate could be predicted with 62.1% sensitivity and 33.1% specificity (Table 5). When the first admission-day laboratory parameters were evaluated in multivariate analysis, higher than cut- off levels of leukocyte (> 2950 µl), ALT (>119.5 u /l), LDH (> 967 u /l) and APTT (> 42.4 s) were found as an independent factors for mortality (OR: 8.03, OR: 7.26, OR:
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8.71 and OR: 12.1, respectively) (Table 6). Discussion
CCHF has been a public health concern in Turkey since 2002 because of the severity and widespread geographic distribution of disease. Case fatality rates were reported as the range
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of 5 - 30% (7, 9, 15). Geographic regions and transmission types are the main factor which seems to have an important impact on mortality rate (2, 8). Higher mortality rates were reported from China (80%) and United Arab Emirates (73%) (15). Geographical differences of the fatality rates were thought to be due to the affect of the transmission routes and
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enhanced supportive care facilities (7). Nosocomially transmitted CCHF had higher mortality rates due to the higher viral load. In the present study, case fatality rate was found as 16.4%. As severe patients were referred to our hospital for intensive supportive therapy, our fatality
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rate was higher than average rate of Turkey (9, 13). In the current study we aimed to
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determine the impact of the leukocyte, neutrophil, lymphocyte and monocyte levels on survival in addition to known predictors of mortality. Living in rural area has been defined as a risk factor for CCHF. Most of the patients with CCHF are observed between March and July in Turkey due to the increased activity in agriculture and animal husbandry. The peak is usually seen in June and July (16). In our study population, 85.9% of the patients were admitted to the hospital between May- June in line with the literature (2). Strong correlation was determined between CCHF and the season,
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dealing with livestock/ farming (75%) and living in the rural areas (77.7%) which are the known risk factors for CCHF. Male / female ratio was similar (55.9% vs. 44.1%) as it was reported previously (16). Tick bite history was 63.6% in the present study which was reported approximately 60% by the Turkish Ministry of Health (17). The mean time for the occurrence of clinical manifestations was 3.8 ± 3.0 days after the tick bite. The most frequent symptoms
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of the patients were fever (88.2%), lack of appetite (79.1 %) and myalgia (75 %) as it was reported in the literature. Additionally, all defined severity criteria were found significantly higher in our fatal cases such as thrombocytopenia, prolonged APTT, PT, INR and decreased level of fibrinogen, elevated level of ALT, AST, LDH and CK in laboratory findings. Also somnolence, diarrhea, all types of hemorrhages and skin lesions were found significantly
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higher in fatal cases (8, 13). The frequencies of hemorrhagic findings were reported on average 25% for the CCHF patients in Turkey (9). However, 66.7% of our patients had hemorrhages. That’s why the higher fatality rate than average of Turkey was determined in
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the present study.
The analysis of relationship between leukocyte counts and mortality rates showed us some important clues for pathogenesis of CCHF. When the first admission-day leukocyte counts
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were compared between fatal and non-fatal cases, WBC and neutrophil levels were found significantly higher in fatal cases. In comparison of the third admission-day laboratory values,
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higher levels of neutrophils and lower levels of lymphocytes and monocytes were determined in fatal cases which were statistically significant. A suggestion can be made that in fatal cases, the increase in neutrophils lead to excessive release of cytokines and the decrease in lymphocytes and monocytes cause depletion in humoral immunity and antibody response. When we compared the first and third admission-day laboratory values, increases of leukocytes, lymphocytes and monocytes were statistically significant in non-fatal cases. However, there was no significant difference in fatal cases. This finding reveals that while
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leukocyte, lymphocyte and monocyte counts turning to the normal levels in nonfatal cases, no improvement was seen in fatal cases. The cut- off levels of some laboratory parameters (leukocyte > 2950 µl, ALT > 119.5 u /l, LDH > 967 u /l, APTT (> 42.4 s) can also help us to predict the prognosis of the disease. The mortality risk may be 7-12 folds higher in patients
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independent predictors of mortality in the present study.
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with these laboratory parameters upper than the cut-off levels which were determined as an
In conclusion, our study revealed that in addition to previously reported severity risk factors, the decrease of monocyte and lymphocyte counts and the increase of neutrophil counts have a correlation with poor outcome in CCHF patients. These results suggest the importance of
Conflict of Interest
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mononuclear immune response for survival in CCHF.
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We don’t have financial relationship with any organization for sponsoring this research.
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Table 1. Demographical, epidemiological and clinical characteristics of patients with CCHF Total cases (%) Non-fatal cases (%) Fatal case p-value Characteristics n=184 s (%) n=220 n=36 50.2 ± 17.0 49.4 ± 17.2 54.0 ±16.0 0.172 Age ( years, mean) ± SD 123 (55.9) 104 (56.5) 19 (52.8) 0.679 Male 32 (14.5) 24 (13.0) 8 (22.2) 0.174 Comorbidities 171 (77.7) 144 (78.3) 27 (75.0) 0.667 Living in rural area 138 (75.0) 27 (75.0) 1.000 Handling livestock/farmi 165 (75.0) ng 119 (64.7) 21 (51.5) 0.470 Bite / contact history wit 140 (63.6) h tick 3.8 ± 2.9 4.0 ± 3.9 0.765 Time from tick bite to on 3.8 ± 3.0 set of symptoms (days) 5.0 ± 3.4 4.8 ± 2.4 0.949 Duration of symptoms be 5.0 ± 3.3 fore hospitalization (day s) 7.3 ± 3.3 4.3 ± 3.0 Length of hospital stay (d 6.8 ± 3.5
