Abstract
Aims
Atherosclerosis is an inflammatory process with different cardiovascular risk factors (CVRFs) contributing to its pathogenesis. We aimed to evaluate the specific relationship between circulating blood leukocytes, troponin I and CVRFs.
Methods
We prospectively enrolled 959 patients with evidence of acute coronary syndrome either in form of unstable angina or STEMI or NSTEMI. Details demographic characteristics, CVRF and biochemical parameters such as total white blood cells (WBC), neutrophil, lymphocytes, platelet, neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), and troponin I were collected.
Results
The results indicated that patients having either hypertension, diabetes or smoking habit had significantly higher levels of total WBC (p = 0.013), neutrophil (p = 0.029), NLR (p = 0.029) and PLR (p = 0.009). The level of troponin I was unaffected by these risk factors. Significant association of hypertension was found with total WBC (p = 0.0392), lymphocytes (p = 0.0384) and PLR (p = 0.0027), whereas in diabetes and females all other leukocyte subtypes were significantly altered except for platelet and troponin I. Smokers had higher level of total WBC count (p = 0.0033) and PLR (p = 0.0464). No relationship between CVRFs and leukocytes was observed in males. The age independent effect was observed with PLR, whereas association with total WBC, lymphocytes, NLR, platelet was specific in older population. In younger patients NLR (p = 0.0453) is more likely to be elevated. Mortality was significantly associated with changes in the leukocytes but not with the CVRF presence.
Conclusion
We demonstrate that the neutrophils, lymphocytes and total WBC along with its ratios predict mortality and are more likely to be elevated in presence of CVRFs.
Keywords: Cardiovascular risk factors, Leukocyte subtypes, Diabetes, Hypertension, Smoking
1. Introduction
The enormous burden and early onset of cardiovascular diseases (CVD) is the challenge imposed to South Asians especially Indians due to urbanization, epidemic transition and genetic susceptibility.1,2 South Asian ethnicity itself is considered as one of the risk factor of CVD and the prevalence of various cardiovascular risk factors (CVRFs) predisposes this population to premature vascular ageing.3
Atherosclerosis, formerly known as a disease of lipid storage is actually a complex cardiac condition involving active and chronic inflammatory process. Hypertension, diabetes, addiction, age, gender and hereditary factors all contribute to the progression of atherosclerosis; however inflammatory cells also play a vital role in this process.4–6 In various animal and human model of atherosclerosis, circulating blood components like neutrophil, lymphocyte, platelets, and other inflammatory mediators were found in the lesions.7 Pathophysiology of atherosclerosis involves chemotactic proteins and adhesion molecules mediated recruitment of circulating leucocytes and platelets to the injured endothelium site.8 Damage to the endothelium upsets the balance between vasoconstriction and vasodilation that promotes the endothelial permeability, platelet aggregation, leukocyte adhesion, and generation of cytokines ultimately initiating deleterious events of atherosclerosis.9
All leukocyte subtype are known to contribute in the development of atherosclerotic plaque and hence the presence of elevated neutrophils, platelets and low lymphocyte are associated with a risk of coronary artery disease (CAD) and are shown to be the predictor of mortality.10 Several studies have documented a link between an elevated leukocyte count to increased short- and longer-term risk for ischemic events and death in patients presenting with acute coronary syndromes (ACS).11 Despite this strong association of circulating inflammatory markers with cardiovascular risk, the connection of these markers with conventional risk factors of CVD is highly unexplored.
The current study was undertaken to investigate the specific relationship of circulating blood components with classical and modifiable CVRFs such as hypertension, diabetes and smoking in ACS patients with prognostic value for this simple assessment.
2. Methods
This prospective and observational study was conducted at U. N. Mehta Institute of cardiology and research centre and was approved by institutional ethics committee (UNMICRC/CARDIO/13/43). All clinical investigations were conducted according to the principles expressed in the Declaration of Helsinki.
2.1. Study subjects
All comer adults presenting with acute coronary syndrome (ACS) diagnosed based on ACC/AHA definition were included as study subjects. Total 959 individuals of both the genders (635 males & 324 females) were enrolled for study from January to December 2013. Any patient with evidence of infection like sepsis, fever were excluded from the study. All patients were also evaluated for Chest X-ray and urine routine and microscopic examination along with to exclude any abnormalities.
2.2. Clinical variables and cardiovascular risk factors
Baseline characteristics were recorded during the direct interview with the patient. Hypertension was defined as the active use of antihypertensive drugs or documentation of blood pressure more than 140/90 mmHg, and diabetes mellitus was defined as fasting plasma glucose (FPG) levels over 126 mg/dl or glucose level over 200 mg/dl at any measurement or active use anti-diabetic treatment. Smoking was defined as current smoking status of an individual. Complete blood count and biochemical values were evaluated from blood samples obtained by antecubital vein puncture. Demographic properties included age and gender, and biochemical parameters included complete blood count and quantitative troponin I. Traditional CVRFs were defined as presence of hypertension, diabetes mellitus and current smoking status.
2.3. Laboratory analysis
Blood sample for laboratory assessment were collected upon first point of patient contact to refrain from bias. Total leucocyte count and its subtypes including neutrophil, lymphocyte and platelet count were analysed using an automated blood cell counter. Troponin I and leukocyte were sent from the same sample to evaluate temporal correlation.
2.4. Statistical methods
All statistical studies were carried out using SPSS program vs 20. Neutrophil/lymphocyte (NLR) ratio and platelet/lymphocyte (PLR) were automatically calculated by loading all the data to the statistical program used. Quantitative variables were expressed as the mean ± standard deviation and qualitative variables were expressed as percentage (%). A comparison of parametric values between two groups was performed using the independent sample t test. Categorical variables were compared using the chi-square test. A nominal significance was taken as a two tailed p value<0.05.
3. Results
3.1. Demographic details, cardiovascular risk factors and inflammatory cells
The demographic details of the patients are presented in Table 1. There were 959 patients having an overall mean age of 57.36 ± 12.48 years. The study cohort was further grouped into the patients with and without the presence of CVRFs. The comparison of the circulating leukocytes from both the groups indicated that patients having either hypertension, diabetes or smoking habit had significantly higher levels of total WBC counts (p = 0.013), neutrophil (p = 0.029), NLR (p = 0.029) and PLR (p = 0.009). Whereas the level of lymphocyte was significantly lower (p = 0.05) in patients having any of the risk factors as compared to the patients having no risk factor. The level of troponin I (p = 0.679) and mortality (p = 0.695) were unaffected by the presence of risk factors. The quartiles (25, 50 and 75) for various inflammatory markers were also found to vary in presence of CVRF.
Table 1.
Demographic characteristics of the population.
| Variables | Total (n = 959) | Patient having no risk factor (n = 239) | Patient having risk factor (n = 720) | P value |
|---|---|---|---|---|
| Gender | Male- 635 (66.21) Female- 324 (33.78) | Male- 151 (63.18) Female- 88 (36.8) | Male- 484 (67.22) Female- 236 (32.77) | – |
| Age | 57.36 ± 12.48 | 56.32 ± 13.68 | 57.7 ± 12.05 | 0.139 |
| Total WBC | ||||
| Mean ± SD | 11395.36 ± 7393.9 | 10365.48 ± 3523.21 | 11737.22 ± 8262.22 | 0.013 |
| Quartiles 25 | 8473 | 8330 | 8507 | |
| 50 | 10340 | 9856 | 10600 | |
| 75 | 13300 | 11500 | 13800 | |
| Neutrophil | ||||
| Mean ± SD | 71.74 ± 10.267 | 70.48 ± 10.67 | 72.16 ± 10.10 | 0.029 |
| Quartiles 25 | 65 | 63 | 65 | |
| 50 | 73 | 72 | 74 | |
| 75 | 80 | 79 | 80 | |
| Lymphocyte | ||||
| Mean ± SD | 22.59 ± 13.81 | 24.78 ± 22.77 | 21.86 ± 8.96 | 0.05 |
| Quartiles 25 | 15 | 16 | 15 | |
| 50 | 20 | 21 | 20 | |
| 75 | 28 | 29 | 27 | |
| NLR | ||||
| Mean ± SD | 4 ± 2.115 | 3.74 ± 2.02 | 4.09 ± 2.13 | 0.029 |
| Quartiles 25 | 2.33 | 2.16 | 2.40 | |
| 50 | 3.60 | 3.27 | 3.65 | |
| 75 | 5.33 | 4.93 | 5.33 | |
| Platelet | ||||
| Mean ± SD | 284244.54 ± 111792.2 | 280599.37 ± 104688.36 | 285454.52 ± 114096.61 | 0.561 |
| Quartiles 25 | 211000 | 212000 | 211000 | |
| 50 | 271000 | 262000 | 274000 | |
| 75 | 346000 | 344700 | 346075 | |
| PLR | ||||
| Mean ± SD | 0.15 ± 0.087 | 0.13 ± 0.06 | 0.15 ± 0.09 | 0.009 |
| Quartiles 25 | 0.09 | 0.09 | 0.02 | |
| 50 | 0.13 | 0.12 | 0.16 | |
| 75 | 0.19 | 0.17 | 3.46 | |
| Troponin I | ||||
| Mean ± SD | 6.32 ± 13.97 | 5.94 ± 14.01 | 6.37 ± 13.91 | 0.679 |
| Quartiles 25 | 0.02 | 0.01 | 0.02 | |
| 50 | 0.14 | 0.06 | 0.16 | |
| 75 | 2.94 | 2.35 | 3.46 | |
| Mortality | 96 (10.01) | 26 (10.88) | 70 (9.72) | <0.001 |
WBC: white blood cell, NLR: neutrophil lymphocyte ratio, PLR: platelet lymphocyte ratio, SD: standard deviation.
3.2. Association between cardiovascular risk factors, cardiac troponin I and inflammatory markers
The influence of individual CVRF on blood cells and troponin I is tabulated in Table 2. Effect of hypertension, diabetes, smoking and ageing was most profound and common on total WBC count. The mean WBC count (12020.14 ± 8019.74) of the smokers were highest followed by diabetic (11745.53 ± 9881.11) and hypertensive (11652.50 ± 9173.54) patients. However in comparison to patients having no CVRFs, neutrophil counts were significantly (p = 0.0101) elevated (72.81 ± 9.79 vs 70.48 ± 10.67) in diabetics only. The mean lymphocyte count in patients suffering from hypertension or diabetes were 21.98 ± 9.07 and 21.49 ± 8.76 respectively, which was significantly (p = 0.038 & p = 0.025) lower as compared to patients having no risk factors (24.78 ± 22.77). In case of NLR, elevation was observed in diabetics (4.15 ± 2.10 vs 3.74 ± 2.02) and smokers (4.11 ± 2.18 vs 3.74 ± 2.02), which could not reach to a statistically significant level in hypertensive population (p = 0.081). The PLR was highly influenced by high blood pressure (0.15 ± 0.09; p = 0.003), sugar levels (0.16 ± 0.09; p < 0.0001) and smoking (0.15 ± 0.009; p = 0.004) whereas the levels of troponin were unaltered by any of the CVRF. Mortality incidence were comparable in all four groups.
Table 2.
Association between specific CVRFs, cardiac troponin I and inflammatory markers.
| Variables | Patient having no risk factor (n = 239) | Hypertension (n = 351) | P- value | Diabetes (n = 285) | P- value | Smoker (n = 282) | P- value |
|---|---|---|---|---|---|---|---|
| Total WBC | |||||||
| Mean ± SD | 10365.48 ± 3523.21 | 11652.50 ± 9173.54 | 0.039 | 11745.53 ± 9881.11 | 0.041 | 12020.14 ± 8019.74 | 0.003 |
| Quartiles 25 | 8330 | 8300 | 8374 | 8673 | |||
| 50 | 9856 | 10400 | 10400 | 10800 | |||
| 75 | 11500 | 13600 | 13800 | 14005 | |||
| Neutrophil | |||||||
| Mean ± SD | 70.48 ± 10.67 | 71.96 ± 10.11 | 0.088 | 2.81 ± 9.97 | 0.010 | 72.24 ± 10.30 | 0.057 |
| Quartiles 25 | 63 | 65 | 67 | 65 | |||
| 50 | 72 | 74 | 74 | 74 | |||
| 75 | 79 | 80 | 80 | 80 | |||
| Lymphocyte | |||||||
| Mean ± SD | 24.78 ± 22.77 | 21.98 ± 9.07 | 0.038 | 21.49 ± 8.76 | 0.025 | 21.96 ± 9.21 | 0.057 |
| Quartiles 25 | 16 | 15 | 15 | 15 | |||
| 50 | 21 | 20 | 20 | 20 | |||
| 75 | 29 | 27 | 27 | 27 | |||
| NLR | |||||||
| Mean ± SD | 3.74 ± 2.02 | 4.04 ± 2.06 | 0.081 | 4.15 ± 2.10 | 0.024 | 4.11 ± 2.18 | 0.046 |
| Quartiles 25 | 2.17 | 2.32 | 2.52 | 2.36 | |||
| 50 | 3.27 | 3.7 | 3.70 | 3.70 | |||
| 75 | 4.94 | 5.33 | 5.33 | 5.35 | |||
| Platelet | |||||||
| Mean ± SD | 280599.4 ± 104688.4 | 284854.01 ± 116778.8 | 0.651 | 291689.2 ± 123047.9 | 0.272 | 278164.8 ± 106152.9 | 0.793 |
| Quartiles 25 | 212000 | 209000 | 211000 | 208000 | |||
| 50 | 262000 | 275400 | 271000 | 264000 | |||
| 75 | 344700 | 346100 | 358050 | 338950 | |||
| PLR | |||||||
| Mean ± SD | 0.13 ± 0.06 | 0.15 ± 0.09 | 0.003 | 0.16 ± 0.09 | <0.0001 | 0.15 ± 0.09 | 0.004 |
| Quartiles 25 | 0.09 | 0.09 | 0.09 | 0.09 | |||
| 50 | 0.12 | 0.13 | 0.13 | 0.13 | |||
| 75 | 0.18 | 0.20 | 0.21 | 0.20 | |||
| Troponin I | |||||||
| Mean ± SD | 5.94 ± 14 | 4.96 ± 12.16 | 0.367 | 5.72 ± 13.5 | 0.855 | 8.40 ± 15.6 | 0.061 |
| Quartiles 25 | 0.01 | 0.01 | 0.02 | 0.03 | |||
| 50 | 0.06 | 0.12 | 0.17 | 0.30 | |||
| 75 | 2.346 | 2.080 | 2.354 | 6.682 | |||
| Mortality | 26 (10.88%) | 40 (11.4%) | 0.950 | 36 (12.63%) | 0.639 | 22 (7.8%) | 0.290 |
WBC: white blood cell, NLR: neutrophil lymphocyte ratio, PLR: platelet lymphocyte ratio, SD: standard deviation.
3.3. The impact of gender and age on cardiovascular risk factors, cardiac troponin I and inflammatory cells
Incidences of hypertension (46.6% vs 34.56%) and diabetes (34.56% vs 27.2%) were higher in females as compared to males, however the habit of smoking was more prevalent in males (13.9% vs 37.3%). The relationship of gender with various CVRFs were analysed and are shown in Table 3. There was no association amongst males where none of the CVRF in patients with risk factor was neither significantly elevated nor lowered in comparison to patients having no risk factor. Contrarily, in females a strong association of total WBC count (p = 0.023), neutrophil (p = 0.0005), lymphocyte (p = 0.001), NLR (p = 0.001) and PLR (p = 0.007) with CVRFs was observed. Age-induced changes in the correlation between CVRFs and WBC subtypes are presented in Table 4. In young (≤40 years), the NLR (4.17 ± 2.23 vs 3.2940 ± 1.88; p = 0.045) and PLR (0.159 ± 0.077 vs 0.127 ± 0.063; p = 0.032) were influenced by the presence or absence of the CVRFs. The population > 40 years of age showed changes in WBC (11773.38 ± 8560.12 vs 10361.67 ± 3620.72; p = 0.023), lymphocyte (21.88 ± 8.94 vs 24.68 ± 24.58; p = 0.014), platelets (283976.45 ± 113343.38 vs 27187.25 ± 91602.9; p = 0.032) and PLR (0.1543 ± 0.09 vs 0.139 ± 0.07; p = 0.034) in presence of various CVRFs.
Table 3.
The impact of gender on CVRFs, cardiac troponin I and inflammatory markers.
| Variables | Male (with no risk factor) n = 151 | Male (with risk factor) n = 484 | P value | Female (with no risk factor) n = 88 | Female (with risk factor) n = 236 | P value |
|---|---|---|---|---|---|---|
| Total WBC | 10986.36 ± 3782.55 | 11644.93 ± 6813.88 | 0.257 | 9300.11 ± 2733.51 | 11926.50 ± 10648.02 | 0.023 |
| Neutrophil | 72.32 ± 9.94 | 72.29 ± 10.11 | 0.975 | 67.34 ± 11.21 | 71.89 ± 10.12 | 0.001 |
| Lymphocyte | 21.98 ± 11.15 | 21.80 ± 9.07 | 0.841 | 29.75 ± 34.14 | 22.01 ± 8.76 | 0.001 |
| NLR | 4.074 ± 2.021 | 4.1208 ± 2.16 | 0.814 | 3.18 ± 1.90 | 4.0287 ± 2.11 | 0.001 |
| Platelets | 267493.05 ± 82639.56 | 278569.07 ± 111445.35 | 0.260 | 303088.64 ± 131898.48 | 299575.55 ± 118340.85 | 0.818 |
| PLR | 0.1416 ± 0.07 | 0.1511 ± 0.09 | 0.231 | 0.1306 ± 0.07 | 0.1620 ± 0.1 | 0.007 |
| Troponin I | 8.03 ± 16.27 | 7.2832 ± 14.93 | 0.600 | 2.36 ± 7.74 | 4.50 ± 11.35 | 0.104 |
WBC: white blood cell, NLR: neutrophil lymphocyte ratio, PLR: platelet lymphocyte ratio, SD: standard deviation.
Table 4.
The impact of age on CVRFs, cardiac troponin I and inflammatory markers.
| Variables | Age ≤ 40 (with no risk factor) n = 39 | Age ≤ 40 (with risk factor) n = 60 | P value | Age > 40 (with no risk factor) n = 200 | Age > 40 (with risk factor) n = 660 | P value |
|---|---|---|---|---|---|---|
| Total WBC | 10385.08 ± 3015.23 | 11339.55 ± 3643.13 | 0.177 | 10361.67 ± 3620.72 | 11773.38 ± 8560.12 | 0.023 |
| Neutrophil | 68.23 ± 10.23 | 72.32 ± 10.00 | 0.052 | 70.93 ± 10.72 | 72.15 ± 10.12 | 0.141 |
| Lymphocyte | 25.31 ± 9.15 | 21.73 ± 9.27 | 0.062 | 24.68 ± 24.58 | 21.88 ± 8.94 | 0.014 |
| NLR | 3.2940 ± 1.88 | 4.17 ± 2.23 | 0.045 | 3.8329 ± 2.04 | 4.08 ± 2.13 | 0.148 |
| Platelets | 298097.43 ± 155960.56 | 301713.33 ± 121897.14 | 0.898 | 27187.25 ± 91602.90 | 283976.45 ± 113343.38 | <0.0001 |
| PLR | 0.127 ± 0.06 | 0.1592 ± 0.08 | 0.032 | 0.139 ± 0.07 | 0.1543 ± 0.1 | 0.034 |
| Troponin I | 5.01 ± 13.97 | 4.45 ± 11.42 | 0.828 | 6.12 ± 14.04 | 6.54 ± 14.11 | 0.712 |
WBC: white blood cell, NLR: neutrophil lymphocyte ratio, PLR: platelet lymphocyte ratio, SD: standard deviation.
3.4. Association of various inflammatory markers and cardiac troponin I with mortality
Table 5 shows comparison between inflammatory cell types & marker levels of expired and survived patients. Except for PLR (p = 0.903) all other blood cells showed significant association with mortality. Expired patients had raised levels of total WBC (15195.33 ± 16232.93 vs 10972.65 ± 5470.91; p < 0.0001), neutrophil (76.43 ± 9.14 vs 71.22 ± 10.23; p < 0.0001), NLR (5.14 ± 2.28 vs 3.87 ± 2.05; p < 0.0001) and troponin I (12.83 ± 19.9 vs 5.54 ± 1 12.91; p < 0.0001) and lower lymphocyte counts (18.18 ± 8.26 vs 23.09 ± 14.21; p = 0.01) as compared to live patients.
Table 5.
Association of various inflammatory markers and cardiac troponin I with mortality.
| Variables | Expired (n = 96) | Survived (n = 863) | P- value |
|---|---|---|---|
| Total WBC | <0.0001 | ||
| Mean ± SD | 15195.33 ± 16232.93 | 10972.65 ± 5470.91 | |
| Quartiles 25 | 8919.50 | 8400 | |
| 50 | 12200 | 1020 | |
| 75 | 17965 | 129990 | |
| Neutrophil | <0.0001 | ||
| Mean ± SD | 76.43 ± 9.14 | 71.22 ± 10.23 | |
| Quartiles 25 | 72.00 | 65.00 | |
| 50 | 79.50 | 72.00 | |
| 75 | 83.00 | 80.00 | |
| Lymphocyte | 0.01 | ||
| Mean ± SD | 18.18 ± 8.26 | 23.09 ± 14.21 | |
| Quartiles 25 | 12 | 16 | |
| 50 | 15 | 21 | |
| 75 | 22 | 28 | |
| NLR | <0.001 | ||
| Mean ± SD | 5.14 ± 2.28 | 3.87 ± 2.05 | |
| Quartiles 25 | 3.36 | 2.24 | |
| 50 | 5.03 | 3.36 | |
| 75 | 6.92 | 5.00 | |
| Platelet | 0.006 | ||
| Mean ± SD | 254537.81 ± 113740.11 | 28749.11 ± 111150.15 | |
| Quartiles 25 | 177000 | 215000 | |
| 50 | 253450 | 273000 | |
| 75 | 323800 | 348000 | |
| PLR | 0.092 | ||
| Mean ± SD | 0.16 ± 0.09 | 0.14 ± 0.08 | |
| Quartiles 25 | 0.086 | 0.088 | |
| 50 | 0.152 | 0.129 | |
| 75 | 0.213 | 0.193 | |
| Troponin I | <0.001 | ||
| Mean ± SD | 12.83 ± 19.90 | 5.54 ± 12.91 | |
| Quartiles 25 | 0.119 | 0.01 | |
| 50 | 1.072 | 0.11 | |
| 75 | 18.26 | 2.46 |
WBC: white blood cell, NLR: neutrophil lymphocyte ratio, PLR: platelet lymphocyte ratio, SD: standard deviation.
3.5. Correlation between various inflammatory markers, troponin and mortality
Except for PLR, a highly significant association was observed between mortality and total WBC (p < 0.0001), neutrophil (p < 0.0001), lymphocyte (p < 0.0001), platelet (p = 0.009) NLR (p < 0.0001), and troponin I (p < 0.0001) (Table 6). Though comparatively less strong, a significant correlation was found between CVRFs and WBC (p = 0.002), neutrophil (p = 0.047), NLR (p = 0.04) and troponin I (p = 0.046).
Table 6.
Correlation between various inflammatory markers and cardiac troponin I with mortality.
| Risk factors | Mortality | ||
|---|---|---|---|
| Total WBC | Correlation Coefficient | 0.101a | 0.140a |
| Sig. (2-tailed) | 0.002 | 0.000 | |
| Neutrophil | Correlation Coefficient | 0.064b | 0.168a |
| Sig. (2-tailed) | 0.047 | 0.000 | |
| Lymphocyte | Correlation Coefficient | −0.063 | −0.166a |
| Sig. (2-tailed) | 0.052 | 0.000 | |
| NLR | Correlation Coefficient | 0.066b | 0.168a |
| Sig. (2-tailed) | 0.040 | 0.000 | |
| Platelet | Correlation Coefficient | 0.019 | −0.085a |
| Sig. (2-tailed) | 0.557 | 0.009 | |
| PLR | Correlation Coefficient | 0.048 | 0.046 |
| Sig. (2-tailed) | 0.138 | 0.156 | |
| Troponin I | Correlation Coefficient | 0.064b | 0.175a |
| Sig. (2-tailed) | 0.046 | 0.000 |
WBC: white blood cell, NLR: neutrophil lymphocyte ratio, PLR: platelet lymphocyte ratio, SD: standard deviation.
Correlation is significant at the 0.01 level (2-tailed).
Correlation is significant at the 0.05 level (2-tailed).
4. Discussion
In the present study, 959 patients with evidence of unstable angina, STEMI and NSTEMI, showed a strong relationship between circulating leukocyte subtypes with modifiable risk factors of CVD. The association was more specific in female and older population.
Our study findings suggest that effect of WBC, neutrophil, lymphocyte, NLR and PLR share strong relation with different specific CVRFs. In particular, we observed that hypertension has the strong relation with WBC, lymphocytes, and PLR, diabetes has the positive relation with WBC, neutrophil, lymphocytes, NLR and PLR, and smoking had specific association with WBC, NLR and PLR. Male gender with risk factor have no specific relation with circulating blood components and troponin I while the female gender with risk factor have positive effect on WBC, neutrophil, lymphocyte, NLR, and PLR.
Atherosclerosis – a process causing narrowing and hardening of the arteries involves active cellular and passive infiltrative response to endothelial injury and is dominant cause of CAD.12 The inflammatory response involves the activation of leukocytes (white blood cells) and is mediated, in part, by a family of cytokines and chemokines. The participation of immune competent cells producing pro-inflammatory cytokines in atherosclerotic lesion is well documented phenomena.13 Many of the coronary risk factors that predispose a person to the development of atherosclerosis, such as hypercholesterolemia, hypertension, smoking, diabetes, family history of premature CAD and natural ageing are also associated with endothelial dysfunction. These factors cause endothelial injury and contribute to deleterious consequences of atherosclerosis.6,14,15 The crucial role of leukocytes in the inflammatory responses is undebatable. The severity and extent of leukocyte facilitate pathogenicity of inflammation is controllable and repairable in nature. However, in presence of various CVRFs this tightly controlled microenvironment becomes highly susceptible to changes.16
Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with diabetes. Prospective studies have demonstrated that increased levels of pro-inflammatory markers such as CRP or reduced levels of anti-inflammatory markers such as adiponectin predict the development of Type 2 diabetes.17–20 Drugs exerting anti-inflammatory and vascular effects have future potential to be used within an array of interventions aimed at reducing the enormous cardiovascular burden associated with Type 2 diabetes. There is some evidence to suggest that this immune activation may precede insulin resistance in diabetic and pre-diabetic states and ultimately may be the factor that initially increases cardiovascular risk in these disease processes.21 Zaidan et al showed that elevation in leukocyte count especially neutrophils have effect on the development of microalbuminuria – process associated with both diabetes and hypertension.22 In one more study, chung et al disclosed the association of peripheral total WBC, neutrophil counts with the advancement of diabetes nephropathy.23 Increased values of NLR and PLR in diabetics was reported by Akbas et al where possible contributors of this association found were increased inflammation and endothelial dysfunction in this population.24 Moreover, the leucocyte counts were also appeared to be an independent predictor for the severity of CAD in diabetes patients.25
Though, inflammatory processes are important participants in the pathophysiology of hypertension the putative underline mechanism of inflammation in hypertension is indistinct. One of the possibility is the hypertension induced arterial wall damage causing endothelial dysfunction and pro-inflammatory changes.12 Another mechanism could be the contribution of IL-17 to the vascular physiology of hypertension facilitating vascular accumulation of leukocytes.26 We have observed significant association of hypertension with total WBC, lymphocytes and PLR. Tatsukawa et al concluded that elevated WBC and neutrophil are associated with hypertension among Japanese population.27 In accordance to our study an elevated PLR in hypertensive patients was reported earlier also.28
Though interaction between WBC count and smoking status has been examined by few previous studies, their results are inconsistent.29–31 Acute cigarette smoke has a suppressive effect on the number of eosinophils and several inflammatory cytokines, possibly due to the anti-inflammatory effect of carbon monoxide.32 Our study also observed that smoking has strong effect on WBC. Other studies found the association between circulating specific leucocyte and smoking and concluded that smoking is specifically related to neutrophil and total WBC.33 In spite of earlier documentation of a positive correlation between smoking and neutrophil percentage, the effect of smoking on platelets and platelet parameters are contradictory.34 One study from Thailand showed no correlation between platelets levels and smoking,35 another study indicted higher platelet counts in smokers,36 which is concomitant with our study results.
The gender difference in the association between leukocytes and CVRFs could be attributed by many factors. The leukocytes tend to increase in presence of CVRFs, and hence higher prevalence of risk factors denote greater degree of correlation between risk factors and WBC subtypes in females.27 Similar results were reported by Bovill et al, where significant relationship between mean WBC counts and peripheral vascular disease was observed in females only.37 Likewise the age related relationship found in current study could be explained by the fact that as the age advances the prevalence of risk factors also increases.
Earlier reports have disclosed that elevated baseline WBC count is a strong and independent predictor for adverse cardiovascular events.38 Investigators of GRACE study examined the relationship between leukocyte count and hospital events among patients presented with an ACS.39 In the same line, our study group also showed strongly association of mortality with circulating inflammatory markers.
5. Conclusion
In this study authors concluded that WBC count and cell types with its various ratios may aid as important prognostic marker in ACS patients with the CVRF.
-
1.
Hypertensive, diabetics, smokers have significantly higher levels of total WBC counts and PLR irrespective of troponin I elevation.
-
2.
Hypertensive patients having ACS had significantly altered total WBC, lymphocytes and PLR.
-
3.
In diabetes all blood cell types and ratios were significantly altered except platelet count and troponin I.
-
4.
Smokers have higher level of total WBC count and NLR.
-
5.
The association of elevated total WBC, lymphocyte and PLR with CVRFs are found more so in females and older population.
-
6.
PLR ratio rises irrespective of age but elderly patients have lower lymphocyte count and higher total WBC and platelet count.
Conflicts of interest
The authors have none to declare.
Acknowledgments
We thank the departmental staff of research, medical record and pathology laboratory for their help and support.
References
- 1.Reddy K.S., Yusuf S. Emerging epidemic of cardiovascular disease in developing countries. Circulation. 1998;97:596–601. doi: 10.1161/01.cir.97.6.596. [DOI] [PubMed] [Google Scholar]
- 2.North K.E., Howard B.V., Welty T.K. Genetic and environmental contributions to cardiovascular disease risk in American Indians: the strong heart family study. Am J Epidemiol. 2003;157:303–314. doi: 10.1093/aje/kwf208. [DOI] [PubMed] [Google Scholar]
- 3.Sharma K.H., Sahoo S., Shah K.H. Are Gujarati Asian Indians ‘older’ for their ‘vascular age’ as compared to their ‘Chronological age’? QJM. 2014;1 doi: 10.1093/qjmed/hcu158. [DOI] [PubMed] [Google Scholar]
- 4.Mathur R.K. Role of diabetes, hypertension, and cigarette smoking on atherosclerosis. J Cardiovasc Dis Res. 2010;1:64–68. doi: 10.4103/0975-3583.64436. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.McGillicuddy F.C., Roche H.M. Nutritional status, genetic susceptibility, and insulin resistance–important precedents to atherosclerosis. Mol Nutr Food Res. 2012;56:1173–1184. doi: 10.1002/mnfr.201100785. [DOI] [PubMed] [Google Scholar]
- 6.Libby P., Ridker P.M., Maseri A. Inflammation and atherosclerosis. Circulation. 2002;105:1135–1143. doi: 10.1161/hc0902.104353. [DOI] [PubMed] [Google Scholar]
- 7.Vitiello L., Spoletini I., Gorini S. Microvascular inflammation in atherosclerosis. IJC Metabolic Endocr. 2014;3:1–7. [Google Scholar]
- 8.Gawaz M., Langer H., May A.E. Platelets in inflammation and atherogenesis. J Clin Invest. 2005;115:3378–3384. doi: 10.1172/JCI27196. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Davignon J., Ganz P. Role of endothelial dysfunction in atherosclerosis. Circulation. 2004;109(23 Suppl 1):III27–32. doi: 10.1161/01.CIR.0000131515.03336.f8. [DOI] [PubMed] [Google Scholar]
- 10.Horne B.D., Anderson J.L., John J.M. Which white blood cell subtypes predict increased cardiovascular risk? J Am Coll Cardiol. 2005;45:1638–1643. doi: 10.1016/j.jacc.2005.02.054. [DOI] [PubMed] [Google Scholar]
- 11.Madjid M., Fatemi O. Components of the complete blood count as risk predictors for coronary heart disease: in-depth review and update. Tex Heart Inst J. 2013;40:17–29. [PMC free article] [PubMed] [Google Scholar]
- 12.Ross R. Atherosclerosis–an inflammatory disease. N Engl J Med. 1999;340:115–126. doi: 10.1056/NEJM199901143400207. [DOI] [PubMed] [Google Scholar]
- 13.Ait-Oufella H., Taleb S., Mallat Z., Tedgui A. Recent advances on the role of cytokines in atherosclerosis. Arterioscler Thromb Vasc Biol. 2011;31:969–979. doi: 10.1161/ATVBAHA.110.207415. [DOI] [PubMed] [Google Scholar]
- 14.Sorensen K., Celermajer D., Georgakopoulos D., Hatcher G., Betteridge D., Deanfield J. Impairment of endothelium-dependent dilation is an early event in children with familial hypercholesterolemia and is related to the lipoprotein (a) level. J Clin Invest. 1994;93:50. doi: 10.1172/JCI116983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Gokce N., Keaney J.F., Hunter L.M., Watkins M.T., Menzoian J.O., Vita J.A. Risk stratification for postoperative cardiovascular events via noninvasive assessment of endothelial function A prospective study. Circulation. 2002;105:1567–1572. doi: 10.1161/01.cir.0000012543.55874.47. [DOI] [PubMed] [Google Scholar]
- 16.Ingram D.D., Gillum R.F. Leukocyte count and cardiovascular risk factors. J Natl Med Assoc. 1992;84:1041. [PMC free article] [PubMed] [Google Scholar]
- 17.Lindsay R.S., Funahashi T., Hanson R.L. Adiponectin and development of type 2 diabetes in the Pima Indian population. Lancet. 2002;360:57–58. doi: 10.1016/S0140-6736(02)09335-2. [DOI] [PubMed] [Google Scholar]
- 18.Mather K.J., Funahashi T., Matsuzawa Y. Adiponectin, change in adiponectin, and progression to diabetes in the diabetes prevention program. Diabetes. 2008;57:980–986. doi: 10.2337/db07-1419. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Thorand B., Zierer A., Baumert J., Meisinger C., Herder C., Koenig W. Associations between leptin and the leptin/adiponectin ratio and incident Type 2 diabetes in middle-aged men and women: results from the MONICA/KORA Augsburg Study 1984–2002. Diabet Med. 2010;27:1004–1011. doi: 10.1111/j.1464-5491.2010.03043.x. [DOI] [PubMed] [Google Scholar]
- 20.Lindberg S., Jensen J.S., Bjerre M. Adiponectin, type 2 diabetes and cardiovascular risk. Eur J Prev Cardiol. 2013 doi: 10.1177/2047487313514894. [DOI] [PubMed] [Google Scholar]
- 21.Festa A., D'Agostino R., Howard G., Mykkänen L., Tracy R.P., Haffner S.M. Chronic subclinical inflammation as part of the insulin resistance syndrome the Insulin Resistance Atherosclerosis Study (IRAS) Circulation. 2000;102:42–47. doi: 10.1161/01.cir.102.1.42. [DOI] [PubMed] [Google Scholar]
- 22.Woodman R.J., Watts G.F., Puddey I.B. Leukocyte count and vascular function in Type 2 diabetic subjects with treated hypertension. Atherosclerosis. 2002;163:175–181. doi: 10.1016/s0021-9150(01)00770-5. [DOI] [PubMed] [Google Scholar]
- 23.Chung F.M., Tsai J.C., Chang D.M., Shin S.J., Lee Y.J. Peripheral total and differential leukocyte count in diabetic nephropathy: the relationship of plasma leptin to leukocytosis. Diabetes Care. 2005;28:1710–1717. doi: 10.2337/diacare.28.7.1710. [DOI] [PubMed] [Google Scholar]
- 24.Akbas E.M., Demirtas L., Ozcicek A. Association of epicardial adipose tissue, neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio with diabetic nephropathy. Int J Clin Exp Med. 2014;7:1794–1801. [PMC free article] [PubMed] [Google Scholar]
- 25.Piot C., Fontbonne A., Sultan A. Inflammatory parameters are independent predictors of severe epicardial coronary stenosis in asymptomatic diabetic patients with silent myocardial ischemia. Diabetes Care. 2003;26:545–546. doi: 10.2337/diacare.26.2.545-a. [DOI] [PubMed] [Google Scholar]
- 26.Harrison D.G., Guzik T.J., Lob H.E. Inflammation, immunity, and hypertension. Hypertension. 2011;57:132–140. doi: 10.1161/HYPERTENSIONAHA.110.163576. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Tatsukawa Y., Hsu W.-L., Yamada M. White blood cell count, especially neutrophil count, as a predictor of hypertension in a Japanese population. Hypertens Res. 2008;31:1391–1397. doi: 10.1291/hypres.31.1391. [DOI] [PubMed] [Google Scholar]
- 28.Sunbul M., Gerin F., Durmus E. Neutrophil to lymphocyte and platelet to lymphocyte ratio in patients with dipper versus non-dipper hypertension. Clin Exp Hypertens. 2014;36:217–221. doi: 10.3109/10641963.2013.804547. [DOI] [PubMed] [Google Scholar]
- 29.Smith M.R., Kinmonth A.L., Luben R.N. Smoking status and differential white cell count in men and women in the EPIC-Norfolk population. Atherosclerosis. 2003;169:331–337. doi: 10.1016/s0021-9150(03)00200-4. [DOI] [PubMed] [Google Scholar]
- 30.Sunyer J., Munoz A., Peng Y. Longitudinal relation between smoking and white blood cells. Am J Epidemiol. 1996;144:734–741. doi: 10.1093/oxfordjournals.aje.a008997. [DOI] [PubMed] [Google Scholar]
- 31.Ishizaka N., Ishizaka Y., Toda E. Relationship between smoking, white blood cell count and metabolic syndrome in Japanese women. Diabetes Res Clin Pract. 2007;78:72–76. doi: 10.1016/j.diabres.2007.02.009. [DOI] [PubMed] [Google Scholar]
- 32.Van der Vaart H., Postma D., Timens W., Ten Hacken N. Acute effects of cigarette smoke on inflammation and oxidative stress: a review. Thorax. 2004;59:713–721. doi: 10.1136/thx.2003.012468. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Ogawa Y., Imaki M., Yoshida Y., Shibakawa M., Tanada S. An epidemiological study on the association between the total leukocyte and neutrophil counts, and risk factors of ischemic heart disease by smoking status in Japanese factory workers. Appl Human Sci. 1998;17:239–247. doi: 10.2114/jpa.17.239. [DOI] [PubMed] [Google Scholar]
- 34.Jensen E.J., Pedersen B., Frederiksen R., Dahl R. Prospective study on the effect of smoking and nicotine substitution on leucocyte blood counts and relation between blood leucocytes and lung function. Thorax. 1998;53:784–789. doi: 10.1136/thx.53.9.784. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Suwansaksri J., Wiwanitkit V., Soogarun S. Effect of smoking on platelet count and platelet parameters: an observation. Clin Appl Thromb Hemost. 2004;10:287–288. doi: 10.1177/107602960401000314. [DOI] [PubMed] [Google Scholar]
- 36.Hung J., Lam J.Y., Lacoste L., Letchacovski G. Cigarette smoking acutely increases platelet thrombus formation in patients with coronary artery disease taking aspirin. Circulation. 1995;92:2432–2436. doi: 10.1161/01.cir.92.9.2432. [DOI] [PubMed] [Google Scholar]
- 37.Bovill E.G., Bild D.E., Heiss G. White blood cell counts in persons aged 65 years or more from the Cardiovascular Health Study correlations with baseline clinical and demographic characteristics. Am J Epidemiol. 1996;143:1107–1115. doi: 10.1093/oxfordjournals.aje.a008687. [DOI] [PubMed] [Google Scholar]
- 38.Munir T., Afzal M. Baseline leukocyte count and acute coronary syndrome: predictor of adverse cardiac events, long and short-term mortality and association with traditional risk factors, cardiac biomarkers and C-reactive protein. J Ayub Med Coll Abbottabad JAMC. 2008;21:46–50. [PubMed] [Google Scholar]
- 39.Furman M.I., Gore J.M., Anderson F.A. Elevated leukocyte count and adverse hospital events in patients with acute coronary syndromes: findings from the Global Registry of Acute Coronary Events (GRACE) Am Heart J. 2004;147:42–48. doi: 10.1016/j.ahj.2003.07.003. [DOI] [PubMed] [Google Scholar]