Association of red cell distribution width, haematocrit and other RBC indices with coronay artery disease: A case control study

Vitthal Khode; Jayaraj Sindhur; Deepak Kanabur; Komal Ruikar; Shobha Nallulwar

doi:10.4103/0189-7969.142088

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ORIGINAL ARTICLE

Year : 2014 | Volume : 11 | Issue : 2 | Page : 88-91

Association of red cell distribution width, haematocrit and other RBC indices with coronay artery disease: A case control study

Vitthal Khode¹, Jayaraj Sindhur², Deepak Kanabur³, Komal Ruikar¹, Shobha Nallulwar¹
¹ Department of Physiology, Shri Dharmasthala Manjunatheshwara College of Medical Sciences, Sattur, Dharwad, Karnataka, India
² Department of General Medicine, Shri Dharmasthala Manjunatheshwara College of Medical Sciences, Sattur, Dharwad, Karnataka, India
³ Department of Pathology, Shri Dharmasthala Manjunatheshwara College of Medical Sciences, Sattur, Dharwad, Karnataka, India

Date of Web Publication

3-Oct-2014

Correspondence Address:
Vitthal Khode
Department of Physiology, SDM College of Medical Sciences, Sattur, Dharwad, Karnataka - 580 009
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/0189-7969.142088

Abstract

Background: Coronary artery disease (CAD) is mainly caused by atherosclerosis and its complications. Red blood cell distribution width (RDW) is a numerical measure of the variability in size of circulating erythrocytes. Several studies reported a strong, independent relation between higher levels of RDW, hematocrit (Hct), and the risk of death and cardiovascular events in people with prior CAD. We tested the hypothesis that RDW, Hct, and other red blood corpuscle (RBC) indices are associated with CAD. Hence, we measured RDW, Hct, and other RBC indices in AMI and stable CAD (SCAD) and compared them with age- and sex-matched controls.
Objectives: To study the changes in RDW and RBC indices in acute myocardial infarction (AMI) and SCAD and compare them with age- and sex-matched controls.
Materials and Methods: This was a comparative study of 128 subjects (39 patients with AMI, 24 patients with SCAD, and 65 controls). Venous sample were drawn from AMI subjects on admission (within 6 h of chest pain) and collected in standardized ethylenediaminetetraacetic acid (EDTA) sample tubes. RDW and RBC indices were assayed within 30 min of blood collection, using Sysmex KX21-N autoanalyzer. Venous samples were also drawn from stable CAD patients who were admitted for angiography and subject attending routine checkups.
Results: There was no significant difference in RDW in patients with CAD (14.12 ± 1.31%) as compared to controls (15.62 ± 6.51%). There was no significant difference in RWD in patients with AMI (14.36 ± 1.4%) as compared to stable CAD (13.7 ± 1.09%) and controls (15.62 ± 6.51%). There was no significant difference in Hct in patients with CAD (43.16 ± 5%) as compared to controls (41.9 ± 6.9%).
Conclusions: There was no association between RWD, Hct, and other RBC indices with CAD, AMI, and stable CAD.

Keywords: Coronary artery disease, hematocrit, red cell distribution width

How to cite this article:
Khode V, Sindhur J, Kanabur D, Ruikar K, Nallulwar S. Association of red cell distribution width, haematocrit and other RBC indices with coronay artery disease: A case control study. Nig J Cardiol 2014;11:88-91

How to cite this URL:
Khode V, Sindhur J, Kanabur D, Ruikar K, Nallulwar S. Association of red cell distribution width, haematocrit and other RBC indices with coronay artery disease: A case control study. Nig J Cardiol [serial online] 2014 [cited 2023 Jun 9];11:88-91. Available from: https://www.nigjcardiol.org/text.asp?2014/11/2/88/142088

Introduction

Acute coronary syndromes (ACSs) are a set of signs and symptoms due to the rupture of a plaque and are a consequence of coronary thrombus formation. The thrombus leads to partial or complete coronary artery occlusion, which, in turn, leads to myocardial ischemia and various clinical manifestations ranging from unstable angina (UA) to acute myocardial infarction (AMI). Red blood cell distribution width (RDW) is a numerical measure of the variability in size of circulating erythrocytes. ^[1] This parameter and hematocrit (Hct) are routinely reported as part of the complete blood count, but its use is generally restricted to narrowing the differential diagnosis of anemia. ^[2] Several studies reported a strong independent relation between higher levels of RDW and the risk of death and cardiovascular events in people with prior coronary artery disease (CAD). ^[3],[4] Similarly, several studies reported a strong independent relation between higher levels of Hct and the risk of death and cardiovascular events in people with CAD. ^[5],[6] Several reports have established strong relation between anemia and the risk of death and cardiovascular events in people with CAD. ^[7] However, whether RDW and Hct are associated with adverse outcomes in persons without heart failure is unknown. We tested the hypothesis that RDW, Hct, and other RBC indices are associated with CAD. Hence, we measured RDW, Hct, and other red blood corpuscle (RBC) indices in AMI and stable CAD (SCAD) and compared them with age- and sex-matched controls.

Materials and methods

This hospital-based, case-control study was designed to assess whether RWD, Hct, and other RBC indices show variation in the spectrum of CAD. The study protocol was approved by the Institutional Review Board of the hospital and written informed consent was obtained from the patients. Sample size was calculated based on standard error obtained in pilot study. One hundred and twenty-eight subjects were recruited and studied in three groups. Group 1A and 1B consisted patients of CAD and Group 2 consisted healthy controls. Group 1A consisted patients of having AMI on admission. Group 1B of SCAD consisted patients of CAD had AMI at least 5 weeks prior and admitted for angiography without chest pain. Following patients were excluded from the study: Anemia (hemoglobin (Hb) <10 g%), polycythemia, severe hepatic or renal impairment, taking oral anticoagulation medicine (but Group 1B patients were thromolysed and all were on antiplatelet therapy), myeloproliferative disorders, and malignancy. The enrolment period was from September 2010 to April 2011.

In Group 1A patients before administration of anticoagulants and antiplatelet drugs, we collected blood samples within 6 h on arrival at casualty into tubes containing ethylenediaminetetraacetic acid (EDTA) that were subsequently diagnosed having AMI. For measurement of Hb, Hct, mean corpuscular volume (MCV), mean corpuscular Hb (MCH), MCH concentration (MCHC), and platelet width distribution (PWD)-standard deviation (SD) and PWD-coefficient of variation (CV), samples were analyzed within 30 min after collection with Sysmex KX21-N automated flow meter. Blood samples of Group B were collected on the day of admission and were analyzed. Group C subjects came for routine checkup and their blood samples were collected on outpatient department.

AMI was diagnosed based on following criteria. Detection of rise or fall in cardiac biomarker Trop I or CKMB with at least one value above 99 ^th percentile of upper limit together with evidence of myocardial ischemia based on at least one of the following: (1) Symptoms of ischemia, (2) electrocardiogram (ECG) changes indicative of new ischemia, (3) development of pathological Q wave in the ECG, and (4) imaging evidence of new loss of viable myocardium or a new regional wall motion abnormality. Group 1B patients diagnosed based on the following criteria: Evidence of AMI at least 5 weeks prior to admission. Their case reports showed; (1) development of pathological Q wave in the ECG and (2) imaging evidence of new loss of viable myocardium or a new regional wall motion abnormality.

Data analysis

The results were presented as mean ± SD or frequency (percentage) as appropriate Group 1A and Group 1B were included in CAD group (Group 1) and compared with control Group 2 using independent t-test. One-way analysis was used for statistical analysis of categorical variables with comparisons of P < 0.05 between Group 1A, 1B, and 2. P < 0.05 was considered statistically significant. A common statistical package (Statistical Package for Social Sciences (SPSS) 16.0, 2007) was used to perform all statistical tests.

Results

During 8 months of study, 128 individuals were selected for the study (17 females and 111 males). AMI was diagnosed in 39 patients (Group 1A). Twenty-four patients had AMI at least 5 weeks prior getting admitted for angiography were enrolled (Group 1B). Sixty-five individuals were selected from medicine outpatient department who were attending for a routine checkup (Group 2).

There was no significant difference between age and sex among the cases and controls. There was no significant increase in RBC count, Hb, hematocrit, MCV, MCH, and MCHC in Group 1 when compared to controls. There was no significant decrease in RWD-SD and RWD-CV in Group 1 when compared to controls [Table 1]. There was no significant difference in age, sex, RBC count, Hb, hematocrit, MCV, MCH, MCHC, RWD-SD, and RWD-CV in group analysis between Group 1A, 1B, and 2 [Table 2].

Table 1: Comparison of RBC indices in cases and controls

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Table 2: Comparison of RBC indices in AMI, SCAD, and controls

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Discussion

In our study, we found that there was no association between RDW, Hct, and other RBC indices among CAD and controls. There was no association between RDW, Hct, and other RBC indices among AMI, SCAD, and controls.

Several previous studies have shown that increased Hct and other RBC indices have been associated to CAD and mortality. Recently, many articles have established association between RDW and CADs. RDW reflects the variability in circulating RBC size. It is based on the width of RBC volume distribution curve, with larger values indicating greater variability. ^[8],[9] RDW is typically increased in conditions of ineffective red cell production (such as iron deficiency, B12 or folate deficiency, and hemoglobinopathies), increased red cell destruction (such as hemolysis), and with blood transfusion. ^[10],[11] Previous studies on RDW were mainly performed in cohorts or randomized trials of patients with significant CAD. ^{[12],[13],[14]} Although these studies showed that RDW was strongly related to CAD events as well as all-cause mortality, data from the Third National Health and Nutrition Examination Survey (NHANES III) showed that RDW significantly predicted deaths from CAD, cancer, chronic lower respiratory tract disease, and other causes except external ones (e.g. traffic accidents). ^[15],[16] But there are very few case-control studies regarding association of increase in RDW and CAD in India. As RDW is associated with multiple causes of death, it is plausible that RDW is influenced by multiple diseases and is an integrative biomarker of dysfunction and impairment across physiological systems.

The clinical utility of RDW beyond its current use in the diagnosis of certain anemia needs to be evaluated. A few studies have shown that RDW might be a useful screening marker for celiac disease, colon cancer, and ACSs in emergency department settings. ^{[17],[18],[19]} Contrast to these studies, we did not observe association between RDW, Hct, and other RBC indices with CAD. This may be because of relatively low sample size due to the study design, attempting to limit the influence of several covariables. However, whether RDW improves risk stratification for individual conditions, such as myocardial infarction or congestive heart failure, is unknown and should be investigated.

Our strength of study was compared to other retrospective reviews of laboratory data, the time between blood sampling and AMI was specified. To our knowledge, we are the first in the literature to study this issue in Indian population, that is, within 6 h of onset of chest pain. Automated cell counters in modern hospital laboratories have made RWD and other indices measurement routinely available. Thus, this effortless laboratory test can be further utilized to reestablish the association between RDW and CAD.

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