Inflammation ( # 2014) DOI: 10.1007/s10753-014-9978-y
The Relationship Between Inflammatory Marker Levels and Pulmonary Tuberculosis Severity Ozlem Abakay,1,2 Abdurrahman Abakay,1 Hadice Selimoglu Sen,1 and Abdullah C. Tanrikulu1
Abstract—We aimed to investigate the correlation between red cell distribution width (RDW), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and other inflammatory markers with pulmonary tuberculosis (PTB) severity. Seventy patients with active pulmonary tuberculosis were compared with 50 age-matched and gender-matched healthy controls. The mean age of PTB patients was 50.4±21.8 years. There were no differences in terms of age, gender, and smoking history between PTB patients and controls. Patients with advanced PTB had a significantly higher white blood cell count, neutrophil count, RDW, NLR, and C-reactive protein when compared to patients with mild to moderate PTB. RDW (17.7 versus 15.7 %, p=0.002) and NLR (4.7 versus 3.1, p=0.009) values were higher in patients with advanced PTB as opposed to patients with mild to moderate PTB. NLR and RDW levels may be used as markers of inflammation to help clinically manage patients with TB and to determine disease severity. KEY WORDS: inflammatory markers; neutrophil to lymphocyte ratio; pulmonary tuberculosis; radiological extent; red blood cell distribution width.
INTRODUCTION Tuberculosis (TB) infections occur by inhaling Mycobacterium tuberculosis bacilli (MTB). Roughly, 10 % of tuberculosis diagnoses are made during the first and second decades of life, and this disease affects three times as many men as women [1]. The progression to active disease results from changes in bacterial virulence and/or an impaired host immune system. The most significant risk factor that promotes the progression of latent to active disease is contracting HIV while infected with TB [2]. The current understanding of the immunology of mycobacterial infections has provided insight into how PTB causes self-limited hematological abnormalities. Developing point-of-care diagnostic testing will greatly benefit public health by decreasing morbidity and mortality and reducing TB transmission rates. Yet in order to develop such a test, it is necessary to determine biomarkers that are both highly specific and sensitive in detecting active TB. Recently, several studies suggested 1
Department of Chest Diseases, Medical Faculty, Dicle University, Diyarbakir, Turkey 2 To whom correspondence should be addressed at Department of Chest Diseases, Medical Faculty, Dicle University, Diyarbakir, Turkey. E-mail: [email protected]
that C-reactive protein (CRP), platelet count, plateletcrit (PCT), and platelet distribution width (PDW) may be potential biomarkers of PTB severity [3–5]. Red blood cell distribution width (RDW) is a measure of the size variability of circulating blood cells and is part of the complete blood count (CBC) panel. It is mainly used as a tool in the differential diagnosis of anemia, but the RDW may be elevated in any condition in which reticulocytes are released into the circulation such as inflammatory diseases and sepsis [6, 7]. In addition to diagnosing anemia, recent studies have demonstrated that RDW also gives information regarding the prognosis of congestive heart failure, acute myocardial infarction, pulmonary embolism, pneumonia, obstructive sleep apnea syndrome, chronic obstructive pulmonary disease, sepsis, and other illnesses [7–11]. It is not completely understood why RDW is elevated in these patients, but it has been suggested that inflammation contributes to higher RDW levels [11]. White blood cell count (WBC) is a well-known indicator of inflammation. In recent years, several studies investigated the potential role of various leukocyte ratios in chronic inflammatory diseases [12–15]. The inflammatory response is central to the pathophysiology of PTB. To the best of our knowledge, an investigation regarding whether the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and RDW are biomarkers of
0360-3997/14/0000-0001/0 # 2014 Springer Science+Business Media New York
Abakay, Abakay, Sen, and Tanrikulu active PTB has not yet been published. As chronic inflammation has been found to be associated with increased inflammatory marker levels in PTB patient serum, we hypothesized that RDW, NLR, and PLR levels are also affected by PTB severity. The objective of this study was to investigate the relationship between the RDW, NLR, and PLR and known acute phase reactants in patients with chest X-ray-confirmed active PTB.
MATERIALS AND METHODS Patients This is a retrospective chart review study. Data were collected by scanning Dicle University Hospital patient records archived from January 2011 to December 2013. In this time frame, there was record of 70 culture-positive pulmonary tuberculosis patients. We then included 50 agematched and gender-matched healthy controls. This study was performed in accordance with the principles of the Declaration of Helsinki and was reviewed and approved by the Dicle University Medical Faculty ethics committee. Patients were excluded from the study if they were taking antibiotics or had conditions that are known to affect WBC counts such as hematologic disorders, chronic inflammatory conditions, severe cardiovascular disease, chronic inflammatory diseases, significant liver disease, autoimmune disorders, neoplasms, and being immunocompromised. Further exclusion criteria were if hemogram data were missing from the chart, if the patient was mistakenly diagnosed with PTB, or if the patient was found to have pulmonary edema during follow-up. Demographics such as age, gender, current smoking status, and smoking history were obtained. Clinical data such as symptoms, duration of symptoms, and history of previous TB infections were gathered. Lastly, laboratory findings including hemogram parameters, serum CRP level, and erythrocyte sedimentation rate (ESR) were archived in the patient files. Symptom duration was defined as the time between symptom onset and diagnosis. Patients were assigned into the pulmonary TB group once MTB was cultured from samples obtained from either sputum or bronchial lavage. A positive diagnosis for active PTB consisted of detecting acid fast bacilli with Ziehl–Neelsen stain from sputum samples and at least one positive culture in Löwenstein–Jensen media using the BACTEC TB 460 system. All patients in this study met these criteria for active PTB. Patients with PTB were classified according to the extent of disease evident on chest radiography: stage 1 was
minimal to mild disease, stage 2 was moderate disease, and stage 3 was advanced disease [5, 16, 17]. Lesions were considered minimal if there was no evidence of cavitation and the lesions were of slight to moderate density located above the second chondrosternal junction. Moreover, the lesions must only involve a segment of one or both lungs, and the combined extent of the lesions must be smaller than the volume of a single lung. Disseminated lesions of slight characterized moderate disease to moderate density in one or both lungs, and the collective lesion volume cannot exceed that of a single lung. In moderate disease, the lesions may also be densely packed so to appear confluent, but areas of high-density lesions cannot take up more than one third of the volume of one lung. Moreover, the total diameter of cavitations cannot exceed 4 cm in patients with moderate disease. If lesions were found to be more extensive than moderate disease, then it was considered advanced disease. After PTB patients were classified according to stage, they were divided into two groups: group 1 consisted of patients with mild–moderate disease, and group 2 patients had advanced disease. Laboratory Analysis All laboratory samples were collected before the patients were started on treatment. Complete blood count analyses were performed with the Beckman Coulter LH750 Hematology Analyzer (Beckman Coulter, Inc., Fullerton, CA, USA). In accordance with hospital laboratory policy, the CBC was performed within 1 h of sample collection. Analyses were performed at room temperature. Total WBC, neutrophil, lymphocyte, and platelet counts in addition to PDW, mean platelet volume (MPV), and RDW were determined by performing CBC analyses. The NLR was defined as the absolute neutrophil count divided by the absolute lymphocyte count. The PLR was defined as the absolute platelet count divided by the absolute lymphocyte count. Serum CRP levels were measured by the immunoturbidometric method (Roche Diagnostics, GmbH, Mannheim, Germany) within 1 h of sample collection, and a normal CRP value was 0.5 mg/dL. Statistical Analysis The Kolmogorov–Smirnov test was used to test whether continuous variables conformed to a normal distribution. Data that followed a normal distribution were expressed as the mean±one standard deviation. The independent Student’s t test and the χ2 test or Fisher’s exact test were utilized to compare data between patient subgroups. Student’s t test, used to evaluate normally distributed data,
Inflammatory Marker Levels and Pulmonary Tuberculosis Severity or the Mann–Whitney U test, used to evaluate data that do not conform to a normal distribution, was used to compare data between two groups. The Spearman test was used to assess the correlation between variables. Statistical analyses were performed with the Statistical Package for Social Sciences version 15 for the Windows® operating system (SPSS® Inc. Chicago, IL, USA). Two-tailed statistical significance testing was performed, and p values less than 0.05 were considered significant.
RESULTS A total of 70 patients diagnosed with PTB and 50 agematched and gender-matched healthy control subjects were included in this study. For the PTB patients, the mean age was 50.4±21.8 years, and ages ranged from 18 to 82 years; the average age for controls was 48.5±14.6 years ranging from 19 to 86 years. In PTB group, 67 % of patients were male, and 66 % of patients were male in the control group. Thirty-seven (52.8 %) of the PTB patients were smokers. During the diagnosis, 66 (94 %) patients had cough, 54 (77 %) had dyspnea, and 40 (57 %) had weight loss. Demographic and clinical characteristics of both patient and control groups are shown in Table 1. There were no differences in age, gender, and smoking history between PTB patients and control subjects (p>0.05). Neutrophil count, platelet count, RDW, PDW, NLR, PLR, ESR, and CRP values were significantly higher in PTB group when compared to the control group (Table 2). Patients with advanced PTB had a significantly higher
Table 2. Comparison of Laboratory Results Between PTB Patients and Controls Parameter
PTB patients (n=70)
Controls (n=50)
p value
WBC count (×109/μL) Neutrophil count (×109/μL) Lymphocyte count (×109/μL) Platelet count (×109/μL) PDW (%) MPV (fL) RDW (%) NLR PLR CRP (mg/dL) ESR (mm/h)
9.5±3.3 6.6±2.8 2.2±1.7 352.3±111.0 17.3±1.2 7.4±1.3 16.6±2.6 3.9±2.6 201.1±111.3 6.1±4.2 39.8±21.2
9.7±1.9 5.7±1.4 3.5±0.9 257.2±99.0 10.9±3.2 7.6±1.2 12.5±1.4 1.6±0.3 78.7±39.2 0.3±0.2 5.8±2.1
NS 0.033
The Relationship Between Inflammatory Marker Levels and Pulmonary Tuberculosis Severity Ozlem Abakay,1,2 Abdurrahman Abakay,1 Hadice Selimoglu Sen,1 and Abdullah C. Tanrikulu1
Abstract—We aimed to investigate the correlation between red cell distribution width (RDW), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and other inflammatory markers with pulmonary tuberculosis (PTB) severity. Seventy patients with active pulmonary tuberculosis were compared with 50 age-matched and gender-matched healthy controls. The mean age of PTB patients was 50.4±21.8 years. There were no differences in terms of age, gender, and smoking history between PTB patients and controls. Patients with advanced PTB had a significantly higher white blood cell count, neutrophil count, RDW, NLR, and C-reactive protein when compared to patients with mild to moderate PTB. RDW (17.7 versus 15.7 %, p=0.002) and NLR (4.7 versus 3.1, p=0.009) values were higher in patients with advanced PTB as opposed to patients with mild to moderate PTB. NLR and RDW levels may be used as markers of inflammation to help clinically manage patients with TB and to determine disease severity. KEY WORDS: inflammatory markers; neutrophil to lymphocyte ratio; pulmonary tuberculosis; radiological extent; red blood cell distribution width.
INTRODUCTION Tuberculosis (TB) infections occur by inhaling Mycobacterium tuberculosis bacilli (MTB). Roughly, 10 % of tuberculosis diagnoses are made during the first and second decades of life, and this disease affects three times as many men as women [1]. The progression to active disease results from changes in bacterial virulence and/or an impaired host immune system. The most significant risk factor that promotes the progression of latent to active disease is contracting HIV while infected with TB [2]. The current understanding of the immunology of mycobacterial infections has provided insight into how PTB causes self-limited hematological abnormalities. Developing point-of-care diagnostic testing will greatly benefit public health by decreasing morbidity and mortality and reducing TB transmission rates. Yet in order to develop such a test, it is necessary to determine biomarkers that are both highly specific and sensitive in detecting active TB. Recently, several studies suggested 1
Department of Chest Diseases, Medical Faculty, Dicle University, Diyarbakir, Turkey 2 To whom correspondence should be addressed at Department of Chest Diseases, Medical Faculty, Dicle University, Diyarbakir, Turkey. E-mail: [email protected]
that C-reactive protein (CRP), platelet count, plateletcrit (PCT), and platelet distribution width (PDW) may be potential biomarkers of PTB severity [3–5]. Red blood cell distribution width (RDW) is a measure of the size variability of circulating blood cells and is part of the complete blood count (CBC) panel. It is mainly used as a tool in the differential diagnosis of anemia, but the RDW may be elevated in any condition in which reticulocytes are released into the circulation such as inflammatory diseases and sepsis [6, 7]. In addition to diagnosing anemia, recent studies have demonstrated that RDW also gives information regarding the prognosis of congestive heart failure, acute myocardial infarction, pulmonary embolism, pneumonia, obstructive sleep apnea syndrome, chronic obstructive pulmonary disease, sepsis, and other illnesses [7–11]. It is not completely understood why RDW is elevated in these patients, but it has been suggested that inflammation contributes to higher RDW levels [11]. White blood cell count (WBC) is a well-known indicator of inflammation. In recent years, several studies investigated the potential role of various leukocyte ratios in chronic inflammatory diseases [12–15]. The inflammatory response is central to the pathophysiology of PTB. To the best of our knowledge, an investigation regarding whether the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and RDW are biomarkers of
0360-3997/14/0000-0001/0 # 2014 Springer Science+Business Media New York
Abakay, Abakay, Sen, and Tanrikulu active PTB has not yet been published. As chronic inflammation has been found to be associated with increased inflammatory marker levels in PTB patient serum, we hypothesized that RDW, NLR, and PLR levels are also affected by PTB severity. The objective of this study was to investigate the relationship between the RDW, NLR, and PLR and known acute phase reactants in patients with chest X-ray-confirmed active PTB.
MATERIALS AND METHODS Patients This is a retrospective chart review study. Data were collected by scanning Dicle University Hospital patient records archived from January 2011 to December 2013. In this time frame, there was record of 70 culture-positive pulmonary tuberculosis patients. We then included 50 agematched and gender-matched healthy controls. This study was performed in accordance with the principles of the Declaration of Helsinki and was reviewed and approved by the Dicle University Medical Faculty ethics committee. Patients were excluded from the study if they were taking antibiotics or had conditions that are known to affect WBC counts such as hematologic disorders, chronic inflammatory conditions, severe cardiovascular disease, chronic inflammatory diseases, significant liver disease, autoimmune disorders, neoplasms, and being immunocompromised. Further exclusion criteria were if hemogram data were missing from the chart, if the patient was mistakenly diagnosed with PTB, or if the patient was found to have pulmonary edema during follow-up. Demographics such as age, gender, current smoking status, and smoking history were obtained. Clinical data such as symptoms, duration of symptoms, and history of previous TB infections were gathered. Lastly, laboratory findings including hemogram parameters, serum CRP level, and erythrocyte sedimentation rate (ESR) were archived in the patient files. Symptom duration was defined as the time between symptom onset and diagnosis. Patients were assigned into the pulmonary TB group once MTB was cultured from samples obtained from either sputum or bronchial lavage. A positive diagnosis for active PTB consisted of detecting acid fast bacilli with Ziehl–Neelsen stain from sputum samples and at least one positive culture in Löwenstein–Jensen media using the BACTEC TB 460 system. All patients in this study met these criteria for active PTB. Patients with PTB were classified according to the extent of disease evident on chest radiography: stage 1 was
minimal to mild disease, stage 2 was moderate disease, and stage 3 was advanced disease [5, 16, 17]. Lesions were considered minimal if there was no evidence of cavitation and the lesions were of slight to moderate density located above the second chondrosternal junction. Moreover, the lesions must only involve a segment of one or both lungs, and the combined extent of the lesions must be smaller than the volume of a single lung. Disseminated lesions of slight characterized moderate disease to moderate density in one or both lungs, and the collective lesion volume cannot exceed that of a single lung. In moderate disease, the lesions may also be densely packed so to appear confluent, but areas of high-density lesions cannot take up more than one third of the volume of one lung. Moreover, the total diameter of cavitations cannot exceed 4 cm in patients with moderate disease. If lesions were found to be more extensive than moderate disease, then it was considered advanced disease. After PTB patients were classified according to stage, they were divided into two groups: group 1 consisted of patients with mild–moderate disease, and group 2 patients had advanced disease. Laboratory Analysis All laboratory samples were collected before the patients were started on treatment. Complete blood count analyses were performed with the Beckman Coulter LH750 Hematology Analyzer (Beckman Coulter, Inc., Fullerton, CA, USA). In accordance with hospital laboratory policy, the CBC was performed within 1 h of sample collection. Analyses were performed at room temperature. Total WBC, neutrophil, lymphocyte, and platelet counts in addition to PDW, mean platelet volume (MPV), and RDW were determined by performing CBC analyses. The NLR was defined as the absolute neutrophil count divided by the absolute lymphocyte count. The PLR was defined as the absolute platelet count divided by the absolute lymphocyte count. Serum CRP levels were measured by the immunoturbidometric method (Roche Diagnostics, GmbH, Mannheim, Germany) within 1 h of sample collection, and a normal CRP value was 0.5 mg/dL. Statistical Analysis The Kolmogorov–Smirnov test was used to test whether continuous variables conformed to a normal distribution. Data that followed a normal distribution were expressed as the mean±one standard deviation. The independent Student’s t test and the χ2 test or Fisher’s exact test were utilized to compare data between patient subgroups. Student’s t test, used to evaluate normally distributed data,
Inflammatory Marker Levels and Pulmonary Tuberculosis Severity or the Mann–Whitney U test, used to evaluate data that do not conform to a normal distribution, was used to compare data between two groups. The Spearman test was used to assess the correlation between variables. Statistical analyses were performed with the Statistical Package for Social Sciences version 15 for the Windows® operating system (SPSS® Inc. Chicago, IL, USA). Two-tailed statistical significance testing was performed, and p values less than 0.05 were considered significant.
RESULTS A total of 70 patients diagnosed with PTB and 50 agematched and gender-matched healthy control subjects were included in this study. For the PTB patients, the mean age was 50.4±21.8 years, and ages ranged from 18 to 82 years; the average age for controls was 48.5±14.6 years ranging from 19 to 86 years. In PTB group, 67 % of patients were male, and 66 % of patients were male in the control group. Thirty-seven (52.8 %) of the PTB patients were smokers. During the diagnosis, 66 (94 %) patients had cough, 54 (77 %) had dyspnea, and 40 (57 %) had weight loss. Demographic and clinical characteristics of both patient and control groups are shown in Table 1. There were no differences in age, gender, and smoking history between PTB patients and control subjects (p>0.05). Neutrophil count, platelet count, RDW, PDW, NLR, PLR, ESR, and CRP values were significantly higher in PTB group when compared to the control group (Table 2). Patients with advanced PTB had a significantly higher
Table 2. Comparison of Laboratory Results Between PTB Patients and Controls Parameter
PTB patients (n=70)
Controls (n=50)
p value
WBC count (×109/μL) Neutrophil count (×109/μL) Lymphocyte count (×109/μL) Platelet count (×109/μL) PDW (%) MPV (fL) RDW (%) NLR PLR CRP (mg/dL) ESR (mm/h)
9.5±3.3 6.6±2.8 2.2±1.7 352.3±111.0 17.3±1.2 7.4±1.3 16.6±2.6 3.9±2.6 201.1±111.3 6.1±4.2 39.8±21.2
9.7±1.9 5.7±1.4 3.5±0.9 257.2±99.0 10.9±3.2 7.6±1.2 12.5±1.4 1.6±0.3 78.7±39.2 0.3±0.2 5.8±2.1
NS 0.033
