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Review Article | DOI: https://doi.org/10.31579/2768-0487/149
Department of Medical Laboratory Science, Babcock University, Ilishan. Ogun State, Nigeria.
*Corresponding Author: : Opeyemi Olufeyisola Adesina., Department of Medical Laboratory Science, Babcock University, Ilishan. Ogun State, Nigeria.
Citation: Opeyemi O Adesina., Abdulbasit F Yekinni, (2024), Comparative Study of Laboratory Diagnosis of Sickle Cell Anaemia Using Point-of-Care Testing, and Haemoglobin Electrophoresis in A Hospital Setting, Journal of Clinical and Laboratory Research, 7(7); DOI:10.31579/2768-0487/149
Copyright: © 2024, Opeyemi Olufeyisola Adesina. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Received: 29 August 2024 | Accepted: 04 September 2024 | Published: 10 September 2024
Keywords: : sickle cell anaemia; point-of-care testing; haemoglobin electrophoresis; sicklescan; diagnosis; specificity; sensitivity
Background: Sickle cell anaemia (SCA) is a hereditary blood disorder characterized by abnormal haemoglobin. Haemoglobin electrophoresis is the gold standard for diagnosing SCA, while SickleSCAN is a novel point-of-care (POC) test offering rapid results. This study compares the diagnostic accuracy of SickleSCAN with haemoglobin electrophoresis in detecting SCA.
Objectives: To evaluate and compare the effectiveness of SickleSCAN and haemoglobin electrophoresis in diagnosing sickle cell anaemia among patients at Babcock University Teaching Hospital (BUTH), Ilishan-Remo, Ogun State, Nigeria.
Materials and Methods: A comparative study was conducted between February and March 2024, involving 45 participants diagnosed with different haemoglobin phenotypes. Blood samples were analyzed using both SickleSCAN and haemoglobin electrophoresis. The results were statistically analyzed using SPSS software, employing descriptive statistics, ANOVA, and Pearson correlation to determine the sensitivity and specificity of both methods.
Results: The study included 45 participants: 21 with normal haemoglobin (HbAA, HbAS, HbAC), 19 with HbSS, and 5 with HbSC. SickleSCAN demonstrated high specificity (>99%) and sensitivity (>99%), closely matching the results obtained through haemoglobin electrophoresis. No false positives or negatives were observed, indicating the reliability of SickleSCAN in diagnosing SCA.
Conclusion: SickleSCAN is a reliable and efficient POC test for the diagnosis of SCA, with comparable sensitivity and specificity to haemoglobin electrophoresis. It holds potential as a valuable tool for rapid diagnosis in resource-limited settings.
Sickle cell anaemia (SCA) is a hereditary haemoglobin disorder characterized by the presence of haemoglobin S (HbS) in red blood cells [1]. This mutation leads to the formation of sickle-shaped erythrocytes under low oxygen conditions, causing various clinical complications such as hemolytic anaemia, vaso-occlusive crises, and organ damage. The global burden of SCA is significant, with the highest prevalence observed in Sub-Saharan Africa, India, the Middle East, and the Mediterranean regions. According to the World Health Organization (WHO), approximately 300,000 infants are born with sickle cell disease (SCD) annually, and about 50% of these births occur in Africa [2].
Early diagnosis and management of SCA are crucial for improving the quality of life and reducing mortality rates among affected individuals. Haemoglobin electrophoresis has long been considered the gold standard for diagnosing haemoglobin opathies, including SCA. This technique involves separating different types of haemoglobin based on their electrical charge and molecular size, enabling the identification of abnormal haemoglobin variants such as HbS, HbC, and others [3]. Despite its accuracy, haemoglobin electrophoresis requires specialized laboratory equipment, skilled personnel, and time, limiting its accessibility in resource-constrained settings.
Point-of-care testing (POCT) has emerged as a promising alternative for diagnosing SCA, particularly in low-resource settings. POCT for SCA typically involves rapid diagnostic tests (RDTs) that can be performed at or near the patient’s location, providing immediate results. These tests are designed to be simple, cost-effective, and require minimal training, making them ideal for use in remote areas where access to conventional laboratory facilities is limited [4]. Recent advances in POCT technologies have led to the development of highly sensitive and specific tests for SCA diagnosis, such as the Sickle SCAN® and HemoTypeSC™ [5]. However, the accuracy and reliability of these tests compared to the gold standard haemoglobin electrophoresis remain areas of active research.
The introduction of POCT for SCA diagnosis has the potential to transform the landscape of SCD management, particularly in regions with high disease burden and limited healthcare infrastructure. The ability to rapidly and accurately diagnose SCA at the point of care can facilitate early intervention, reduce the time to treatment initiation, and improve patient outcomes. However, the clinical adoption of POCT requires thorough validation against established diagnostic methods to ensure its efficacy and reliability in diverse healthcare settings.
This comparative study aims to evaluate the diagnostic performance of POCT for SCA in comparison with haemoglobin electrophoresis in a hospital setting. By analyzing the sensitivity, specificity, and overall diagnostic accuracy of both methods, this research seeks to provide evidence-based recommendations for the integration of POCT into routine clinical practice. The findings of this study could have significant implications for SCA screening programs, particularly in resource-limited settings, and contribute to the broader effort to reduce the global burden of sickle cell disease.
Study Design
A comparative study design in research methodology compares two or more groups to identify differences and similarities between the groups. It involves examining the characteristics, outcomes, conditions, or variables. In this project, I compared the standard laboratory diagnosis of Sickle cell anaemia which is haemoglobin electrophoresis against the new point-of-care rapid test kit which is SickleSCAN. The duration of this study was between February and March 2024.
Study Population
Subjects with Sickle cell anaemia HbS at Babcock University Teaching Hospital (BUTH), Ilishan-Remo, Ogun State Nigeria, participated in this study. Informed consent was obtained from each participant, blood samples were collected and questionnaires were administered to gather the basic demographic data and other relevant medical information. There are no risks associated with participating in this study.
Study Area
The study was carried out on individuals with Sickle Cell Anaemia HbS in Babcock University Teaching Hospital (BUTH), Ilishan-Remo, located in the Southern-Western region of Nigeria, coordinates: (Latitude 6.8 0N and Longitude 3.7 0E).
Sample Size Determination
The sample size was determined using the Cochran formula for estimating proportions in a population outlined by Uduma et al. [6]:
According to Uche et al., [7], the existing prevalence of Sickle cell anaemia is 3%.
A total number of 45 participants were selected for the study.
Selection Criteria
For participants to be qualified for selection, several factors were considered in the course of this study
Inclusion Criteria
Exclusion Criterium
Participants who do not consent to the study
Ethical Approval
Ethical approval was obtained from the Babcock University Health Research Ethics Committee (BUHREC) before the commencement of this research work. Consent forms were carefully designed to seek the approval of each subject before the study. Informed consent was obtained from participants before recruiting them for the study. The study's aim, purpose, objectives, nature, and benefit were properly explained to each participant. They were assured of confidentiality, protection, free will to participate, and freedom to withdraw from the study at any time. The participants were requested to complete a consent form which was endorsed by a signature indicating their willingness to partake without any form of pressure.
Sample Collection
Five millilitres (5 ml) of the venous blood sample were collected from each participant into EDTA sample bottles.
Safety Precautions
Laboratory Analysis
Haemoglobin Electrophoresis and SickleSCAN were used to diagnose Sickle cell anaemia HbS.
Diagnosis of Sickle Cell Anaemia HbS Using Haemoglobin Electrophoresis
Haemoglobin electrophoresis being the laboratory standard was used to diagnose Sickle cell anaemia.
Principle
Haemoglobin electrophoresis relies on the principle of separating haemoglobin molecules in an electric field. In this process, a blood sample is placed onto a gel or other support medium and subjected to an electric current. Haemoglobin molecules move through the gel at different rates based on their electrical charge and size, leading to distinct migration patterns. This separation allows for the identification and quantification of various haemoglobin variants present in the sample.
Procedure
The patient’s sample was collected in an EDTA sample bottle. The EDTA sample bottle was mixed gently. The cellulose acetate paper was soaked in an appropriate buffer solution to facilitate migration. The patient's blood sample was applied onto the cellulose acetate paper using a micropipette or capillary tubes. The sample was applied as a narrow line in the center of the paper and the sample was allowed to dry thoroughly. The prepared cellulose acetate paper was carefully placed into the electrophoresis chamber and an electric current was applied to the chamber, initiating the migration of haemoglobin bands across the paper. After the electrophoresis ran, the paper was removed from the chamber to observe and interpret the migration pattern of haemoglobin bands on the cellulose acetate paper.
Diagnosis of Sickle Cell Anaemia Using SickleSCAN
SickleSCAN was used to diagnose Sickle cell anaemia HbS, following the manufacturer’s (BioMedomics, Inc.) procedure.
Principle
SickleSCAN operates based on lateral flow immunoassay principles, utilizing monoclonal antibodies targeting Haemoglobin S (HbS), the hallmark of Sickle Cell Anaemia (McGann et al., 2013). When a blood sample is applied to the test strip, any HbS present binds to these antibodies immobilized on the strip's surface. As the sample migrates across the strip, HbS-antibody complexes move to a specific region where another set of antibodies, specific to HbS, are immobilized. The presence of HbS in the sample leads to a visible line or spot formation on the strip due to the accumulation of the complex at the test line, correlating with the HbS quantity, providing a semi-quantitative measure [4]. SickleSCAN's lateral flow immunoassay provides rapid results within about 5 minutes, making it an efficient tool for immediate identification of abnormal haemoglobin associated with Sickle Cell Anaemia [2].
Procedure
The patient’s sample was collected in an EDTA sample bottle. The EDTA sample bottle was mixed gently. The blood sample was mixed with a buffer solution provided by the manufacturer. 5 drops of the blood buffer solution were placed on the test strip. After 5 minutes, the test strip result was read.
Data was analyzed using the statistical package for the Social Sciences (SPSS) version 18 soft pack. The methods included descriptive statistics (frequencies, means, and standard deviation), ANOVA, and correlation using the Pearson correlation coefficient. The significant threshold will be fixed at P <0>
A total of 45 Subjects were included in this study: 21 normal healthy participants (6 with HbAA, 11 with HbAS, 4 with HbAC), 19 with HbSS, and 5 with HbSC among which 30 were males and 15 were females. The participants were aged 18 to 55 years with a mean age of 36.5 ± 18.5 years. SickleSCAN results were compared to haemoglobin electrophoresis which is the gold standard following the standard procedure at the institution where the samples were collected (Table 1).
Comparison of the SickleSCAN test with electrophoresis (Table 2) shows similar performance in detecting different haemoglobin phenotypes. The majority of samples were correctly identified for each haemoglobin phenotype. The SickleSCAN test demonstrated high specificity and sensitivity, with no false positives or false negatives observed. Both methods achieved high sensitivity and positive predictive value (PPV), indicating their effectiveness in accurately identifying individuals with Sickle Cell Anaemia.
The high specificity (>99%) and sensitivity (>99%) of the SickleSCAN test demonstrate its reliability in distinguishing between different haemoglobin phenotypes associated with Sickle Cell Anaemia. These findings suggest that the SickleSCAN test has the potential to serve as a valuable tool for rapid and accurate diagnosis of Sickle Cell Anaemia, particularly in resource-limited settings where access to laboratory facilities may be limited (Table 2). The results of the SickleSCAN test indicate its effectiveness in accurately identifying haemoglobin phenotypes associated with Sickle Cell Anaemia. The high specificity and sensitivity of the test highlight its potential as a valuable diagnostic tool, particularly in settings where access to traditional laboratory methods may be limited. Further research is warranted to validate these findings and explore the utility of the SickleSCAN test in various clinical settings.
| AA | AS | SC | AC | SS | Total | |
| HbAA | 6 | 0 | 0 | 0 | 0 | 6 |
| HbAS | 0 | 11 | 0 | 0 | 0 | 11 |
| HbSC | 0 | 0 | 5 | 0 | 0 | 5 |
| HbAC | 0 | 0 | 0 | 4 | 0 | 4 |
| HbSS | 0 | 0 | 0 | 0 | 19 | 19 |
| Total | 6 | 11 | 5 | 4 | 19 | 45 |
| Specificity | >99% | >99% | >99% | >99% | >99% | >99% |
| Sensitivity | >99% | >99% | >99% | >99% | >99% | >99% |
Table 1: SickleSCAN Performance Compared to Genotypes Identified by Haemoglobin Electrophoresis Which is the Gold Standard Diagnostic Test of Sickle Cell Anaemia.
| Phenotype | Method | TP | FP | TN | FN | Sensitivity | PPV |
| AA | Electrophoresis | 6 | 0 | 0 | 0 | 1 | 1 |
| SickleSCAN | 6 | 0 | 0 | 0 | 1 | 1 | |
| AS | Electrophoresis | 11 | 0 | 0 | 0 | 1 | 1 |
| SickleSCAN | 11 | 0 | 0 | 0 | 1 | 1 | |
| SC | Electrophoresis | 5 | 0 | 0 | 0 | 1 | 1 |
| AC | Electrophoresis | 4 | 0 | 0 | 0 | 1 | 1 |
| SickleSCAN | 4 | 0 | 0 | 0 | 1 | 1 | |
| SS | Electrophoresis | 19 | 0 | 0 | 0 | 1 | 1 |
| SickleSCAN | 19 | 0 | 0 | 0 | 1 | 1 |
Table 2: The Sensitivity Analysis of Haemoglobin Electrophoresis versus SickleSCAN in the Diagnosis of Sickle Cell Anaemia.
Legends:
True Positive (TP) - Number of true positive event
True Negative (TN) - Number of false negative event
False Positive (FP) - Number of false positive event
False Negative (FN) - Number of false negative event
Sensitivity – TP/ (TP + FN)
Predictive Positive Value (PPV) – TN/ (TN + FN)
The study aimed to evaluate the performance of SickleSCAN, a point-of-care (POC) testing device, against the gold standard diagnostic method, haemoglobin electrophoresis, for the detection of various haemoglobin genotypes in a hospital setting. The results demonstrated a high level of accuracy for SickleSCAN in identifying different haemoglobin genotypes (AA, AS, SC, AC, and SS), with specificity and sensitivity consistently exceeding 99% for all genotypes.
The findings revealed that SickleSCAN accurately identified all genotypes without any false positives or false negatives. This is particularly significant because previous studies have reported varying levels of sensitivity and specificity for different POC tests. For instance, a study by Inusa et al. [8] noted that POC tests for sickle cell disease (SCD) could exhibit lower sensitivity in detecting certain haemoglobin variants like HbSC, which could lead to underdiagnosis in some cases. However, the present study found no such discrepancies, which may indicate improvements in the technology or the specific conditions under which the test was administered.
The excellent performance of SickleSCAN, as indicated by its ability to correctly classify all haemoglobin variants, aligns with other recent studies. McGann et al. [9] also reported high sensitivity and specificity (>99%) for SickleSCAN when compared with haemoglobin electrophoresis in a multi-centre study, suggesting that the test is reliable across various settings. The consistency of these results across different studies reinforces the potential of SickleSCAN as a robust tool for the early diagnosis of SCD, especially in
resource-limited settings where traditional electrophoresis may not be readily available.
The ability of SickleSCAN to perform on par with haemoglobin electrophoresis has significant implications for clinical practice, particularly in regions where access to advanced laboratory facilities is limited. The POC test offers a rapid, cost-effective alternative that can be utilized in primary healthcare settings, potentially increasing the rate of early diagnosis and improving patient outcomes. This is particularly important in areas with high prevalence rates of SCD, such as sub-Saharan Africa, where delays in diagnosis can lead to severe complications or even mortality [2].
Moreover, the accuracy of SickleSCAN in detecting the HbSS genotype, which is associated with the most severe form of SCD, is crucial. Early and accurate diagnosis of HbSS can lead to timely interventions, such as the initiation of prophylactic penicillin and hydroxyurea therapy, which are essential for reducing morbidity and mortality in affected individuals [10].
The results of this study are consistent with those of previous research that has evaluated the accuracy of POC tests for haemoglobin genotype determination. A study by Nnodu et al. [11] in Nigeria reported similar findings, with SickleSCAN demonstrating high sensitivity and specificity for detecting HbSS, HbSC, and HbAS genotypes. This reinforces the utility of POC tests in regions with high SCD burden and limited access to comprehensive laboratory services.
However, some studies have reported challenges with POC tests, particularly regarding their performance in detecting less common genotypes such as HbSC and HbAC. For example, a study by Tshilolo et al. [12] found that certain POC devices had lower sensitivity for these variants, leading to potential diagnostic errors. In contrast, the current study did not encounter these issues, which may be due to advancements in the technology or differences in the study populations.
The sensitivity and PPV for Haemoglobin Electrophoresis and SickleSCAN were both found to be 100
The findings of this study demonstrate that SickleSCAN is as effective as Haemoglobin Electrophoresis in diagnosing Sickle Cell Anaemia and other haemoglobin opathies. Given its high sensitivity, PPV, and operational advantages, SickleSCAN represents a valuable diagnostic tool that can enhance the detection and management of SCA, especially in resource-limited settings. These results support the broader adoption of POC testing in clinical practice, potentially improving access to timely and accurate diagnosis for individuals affected by haemoglobin opathies.
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