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10.1371/journal.pone.0296766
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Diagnostic role of Sysmex hematology analyzer in the detection of malaria: A systematic review and meta-analysis
Diagnostic role of Sysmex hematology analyzer in the detection of malaria
https://orcid.org/0009-0006-9702-6689
Mulatie Zewudu Conceptualization Data curation Formal analysis Funding acquisition Investigation Methodology Project administration Resources Software Supervision Validation Visualization Writing – original draft Writing – review & editing 1 *
Kelem Amanuel Conceptualization Formal analysis Methodology Project administration Software Supervision Writing – original draft Writing – review & editing 2
Chane Elias Conceptualization Formal analysis Resources Visualization Writing – original draft Writing – review & editing 3
Tarekegn Amare Mekuanint Data curation Investigation Software Validation Writing – original draft Writing – review & editing 3
Teketelew Bisrat Birke Data curation Formal analysis Methodology Software Writing – original draft Writing – review & editing 4
Yenesew Abebe Formal analysis Investigation Software Supervision Writing – original draft Writing – review & editing 5
Melkamu Abateneh Formal analysis Investigation Methodology Software Validation Visualization Writing – review & editing 5
Muche Yalew Data curation Formal analysis Methodology Software Validation Writing – review & editing 5
Addisu Bedasa Formal analysis Funding acquisition Software Visualization Writing – original draft Writing – review & editing 2
Berta Dereje Mengesha Conceptualization Formal analysis Project administration Software Supervision Writing – original draft Writing – review & editing 4
1 Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
2 Department of Medical Laboratory Sciences, Asrat Woldeyes Health Science Campus, Debre Berhan University, Debre Berhan, Ethiopia
3 Department of Clinical Chemistry, School of Biomedical and Laboratory Science, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
4 Department Hematology and Immunohematology, School of Biomedical and Laboratory Science, College of Medicine and Health Science, University of Gondar, Gondar, Ethiopia
5 Department of Medical Laboratory Science, College of Medicine and Health Sciences Debre Markos University, Debre Markos, Ethiopia
Agaba Bosco Bekiita Editor
Makerere University Medical School and the National Malaria Control Division, UGANDA
Competing Interests: The authors have declared that no competing interests exist.

* E-mail: zewudumulatie@gmail.com
6 9 2024
2024
19 9 e029676616 10 2023
18 12 2023
© 2024 Mulatie et al
2024
Mulatie et al
https://creativecommons.org/licenses/by/4.0/ 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.

Background

Malaria control depends primarily on rapid and accurate diagnosis followed by successful treatment. Light microscopy is still used as a gold standard method for the diagnosis of malaria. The Sysmex hematology analyzer is a novel method for malaria detection. Therefore, the aim of this review was to investigate the diagnostic accuracy of the Sysmex hematology analyzer for malaria diagnosis.

Methods

Electronic databases like PubMed, PubMed Central, Science Direct databases, Google Scholar, and Scopus were used to find relevant articles from April to June 14, 2023. The studies’ methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Using Review Manager 5.4.1, the estimates of sensitivity and specificity, as well as their 95% confidence intervals, were shown in forest plots. Midas software in Stata 14.0 was utilized to calculate the summary estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio. Heterogeneity was assessed by using I2 statistics. In addition, publication bias was assessed using a funnel plot and Deeks’ test. Sub-group and meta- regression analysis were also performed.

Results

A total of 15 studies were assessed for diagnostic accuracy. The sensitivity and specificity of Sysmex hematology analyzer for studies ranged from 46% to 100% and 81% to 100%, respectively. The summary estimate of sensitivity and specificity of Sysmex hematology analyzer were 95% (95% CI: 85%-99%) and 99% (95% CI: 97%-100%), respectively. It had excellent diagnostic accuracy. There were significant heterogeneity among the studies included in this meta-analysis. The summary estimate of sensitivity and specificity of Sysmex hematology analyzer using polymerase chain reaction as the gold standard was 97.6% (95% CI: 83.2, 99.7) and 99.4% (98.5, 99.8), respectively.

Conclusion

In this review, Sysmex hematology analyzer had excellent diagnostic accuracy. Therefore, it could be used as an alternate diagnostic tool for malaria diagnosis in the hospital and health center.

Trial registration

Systematic review registration PROSPERO (2023: CRD42023427713). https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023427713.

The author(s) received no specific funding for this work. Data AvailabilityAll relevant data are within the paper.
Data Availability

All relevant data are within the paper.
==== Body
pmcIntroduction

Malaria continues to pose a significant global public health challenge, with a significant impact on morbidity and mortality. In 2021, it was estimated that there were approximately 247 million cases of malaria infection and 619,000 reported deaths. The majority of these cases and deaths were concentrated in 29 out of the 84 countries where malaria is endemic, accounting for about 96% of global malaria cases and mortality. Particularly, Africa experienced a large proportion of the burden, with nearly 95% of cases and 96% of deaths occurring in the continent. Among these deaths, approximately 78.9% were children under the age of five. The countries who had the highest number of malaria cases were Nigeria (26.6%), the Democratic Republic of the Congo (12.3%), Uganda (5.1%), and Mozambique (4.1%), collectively contributing to almost half of all cases. Furthermore, four countries—Nigeria (31.3%), the Democratic Republic of the Congo (12.6%), the United Republic of Tanzania (4.1%), and Niger (3.9%)—accounted for slightly over half of all malaria-related deaths worldwide [1]. Early and precise diagnosis is a crucial aspect of malaria elimination efforts.

The World Health Organization (WHO) emphasizes the importance of confirming the diagnosis of suspected malaria cases through either microscopy or a rapid diagnostic test (RDT) before initiating treatment [2]. Malaria diagnosis is typically conducted by visually identifying the parasite under a microscope, which is considered the most applicable diagnostic method in clinical settings [3]. This approach is cost-effective, allows for the quantification of parasitemia, facilitates follow-up during parasitemia clearance, and offers the potential for detecting other diseases. However, microscopic diagnosis is time-consuming, requires skilled personnel, and has limitations associated with the expertise of the observer and its low limit of detection [3].

Conversely, rapid diagnostic tests (RDTs) require less training, offer convenience, and provide results within a short timeframe of approximately fifteen minutes. As a result, RDTs have effectively replaced microscopy in routine diagnosis within health institutions, as well as for active case identification by community health workers, particularly in rural areas [4]. However, RDTs do have limitations in that they are not quantitative and cannot distinguish between different stages of parasite development. Consequently, RDTs have limited utility in assessing treatment efficacy, monitoring progression, and assessing their impact on transmission [5]. In addition, recent reports stated that the RDT cause false negatives in Plasmodium falciparum due to deletions of the gene encoding target histidine rich protein 2/3 (HRP2/3) [6–8]. Plasmodium lactate dehydrogenase (pLDH) detecting RDTs are also available, however they have lesser sensitivity than HRP2-detecting RDTs [9].

Nucleic acid amplification techniques (NAATs), including polymerase chain reaction (PCR), offer superior sensitivity compared to other methods, with reported detection limits as low as 5 parasites per microliter [10–12]. However, these techniques are costly and time-consuming, requiring trained personnel for operation. Additionally, they do not provide useful information for follow-up after treatment and cannot differentiate between different stages of the parasite [3]. The loop-mediated isothermal amplification (LAMP) represents a recently developed molecular technique that stands out for its simplicity, speed, and cost-effectiveness, necessitates fewer equipment and laboratory facilities compared to PCR [13]. Moreover, it exhibits higher sensitivity compared to both microscopy and RDT, making it a promising tool for efficient and accurate detection in various settings [14]. In malaria-endemic regions, there is a demand for improved diagnostic methods that can complement existing approaches, particularly those that offer high sensitivity and ease of use. The automated Sysmex hematology analyzer is an innovative and clinical tool for malaria diagnosis. This advanced technology reduces analysis time and improves accuracy in detecting potential malaria infections. It offers fast, sensitive, and cost-effective examinations for efficient malaria screening [15–17]. The analyzer works by combining optical fluorescence methods, flow cytometry, and laser-optical recognition. The Sysmex hematology analyzer provides a complete blood count (CBC) and classifies distinct blood cell types, as well as directly detects and quantifies plasmodium parasites in blood in one minute and had high a limit of quantification [16].

Several factors influence the selection of diagnostic tests, such as the cost of equipment, the number of tests to be conducted, the presence of trained personnel, the precision of the diagnostic procedure, while practicality and cost-effectiveness are crucial considerations, the paramount importance lies in the test’s accuracy, even if it represents the most practical and economical option in a given scenario. Accuracy remains a critical requirement to ensure reliable diagnostic outcomes [18]. Hence, the objective of this review was to assess the diagnostic accuracy of the Sysmex hematology analyzer for malaria diagnosis.

Methods

Search strategy and study selection

This systematic review and meta-analysis adhered to the PRISMA guidelines for reporting. Several electronic databases, including PubMed, PubMed Central, ScienceDirect, Google Scholar, and Scopus, were searched for relevant studies from April through June 14, 2023. The search employed keywords such as "malaria," "P. falciparum," "P. vivax," "P. ovale," "P. malariae," "diagnosis," "Sysmex hematology analyzer," and "diagnostic test accuracy," with Boolean operators (AND, OR) used to combine the keywords. Overlapping studies across multiple databases were excluded. Additional papers were identified through the reference lists of the included studies. Duplicate studies and those lacking a reference test were excluded. The title and abstract of potentially acceptable research were independently screened by four reviewers. The full text of potentially eligible studies reporting the diagnostic accuracy of the Sysmex hematology analyzer was then assessed for extraction. Any disagreements among authors were resolved through discussion.

Eligibility criteria

This review included original publications that evaluated the diagnostic accuracy of the Sysmex hematology analyzer haematology analyzer for the detection of plasmodium species. Only studies reported in English were considered. Studies reporting the diagnostic accuracy of the Sysmex hematology analyzer for the detection of malaria in non-human subjects (animals, rodents) were excluded. Review papers, case studies, and letters to the editor were also excluded.

Data extraction and management

Data from eligible papers were independently extracted by three reviewers in Microsoft Excel 2010, including information on authors, publication year, region, study subjects, study design, descriptions of reference and index tests, and data for 2x2 tables. The methodological quality of the included studies was assessed using the QUADAS-2 tool, evaluating bias in patient selection, index test, reference standards, and flow/timing [19]. A graph illustrating the risk of bias was created.

Statistical analysis

Statistical analyses were conducted using Review Manager 5.4 for the estimates of sensitivity and specificity, as well as their 95% confidence intervals were shown in forest plots. Midas in Stata14 used for to assess the summary estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio (DOR) were calculated. The hierarchical summary receiver operating characteristic curve (HSROC) was used to assess heterogeneity. Meta-disc 1.4.0 software was employed to determine the presence of a threshold effect if heterogeneity was significant or I2 exceeded 50%. Meta-regression was explored to identify sources of heterogeneity, such as sampling method, study population, sample size, reference method, type of Sysmex hematology analyzer, and parameter detected. Deeks’ funnel plot asymmetry test was performed to assess publication bias.

Results

Description of included studies

Database searches yielded a total of 936 articles, of which 612 were removed due to duplication. A total of 324 papers were screened for their titles and abstracts, and 304 studies were excluded. Among 20 full-text articles reviewed against the eligibility criteria, then 5 full-text articles were excluded. Finally, fifteen articles were eligible and included in the systematic review and meta- analysis of the final analysis (Fig 1).

10.1371/journal.pone.0296766.g001 Fig 1 Flow diagram of the included studies for the systematic review and meta-analysis.

Characteristics of the included studies

The systematic review examined fifteen papers published up to 2023, resulting in 16,501 people being evaluated to evaluate the performance of the Sysmex hematology analyzer [20–33]. In 9 studies (11,220 tests), polymerase chain reaction was employed as a reference method for Sysmex hematology analyzer [20–27]. A microscope was also used as a reference method for 6 Sysmex hematology analyzer testing (5281 tests) [28–33] (Table 1).

10.1371/journal.pone.0296766.t001 Table 1 Characteristics of the studies included in the systematic review and meta-analysis of the performance of Sysmex hematology analyzer.

s. no.	Author (year)	Population	Age in years ((median (IQR))	parasite density ((median (IQR))	Sample size	TP	FP	TN	FN	Sysmex type	Reference test	Reference	
1	M’baya et al (2022) [20]	Malaria suspected	NA	164 (63–448)	5031	513	41	4477	0	XN-31	PCR	[20]	
2	Buoro et al (2018) [28]	Malaria suspected	12–64*	NA	1061	13	200	847	1	XN series	microscope	[28]	
3	Huh et al (2008) [29]	Patients (asymptomatic)	NA	4003.3±6530.2**	487	100	0	343	44	XE-2100	microscope	[29]	
4	Kagaya et al (2022) [21]	Malaria suspected	23 (5–36)	21,774 (9,490 −101,973)	169	18	11	135	5	XN-31	PCR	[21]	
5	Khartabil et al (2022) [30]	Malaria suspected	NA	NA	112	13	1	96	2	XN-31	microscope	[30]	
6	Picot et al (2022) [22]	Febrile patients	36 (1–89)	2.4–288.3*	357	109	4	244	0	XN-31	PCR	[22]	
7	Pillay et al 7a (2019) [23]	Malaria suspected	NA	NA	191	124	0	67	0	XN-30	PCR	[23]	
8	Pillay et al 7b(2019) [23]	Malaria suspected	NA	NA	1028	272	1	749	6	XN‑10	PCR	[23]	
9	Post et al (2019) [24]	Febrile patients	0.67–59*	12,390 (650–88,656)	837	253	2	478	104	XN-30	PCR	[24]	
10	Mohapatra et al (2011) [31]	Malaria suspected	NA	NA	430	52	35	325	18	XE-2100	microscope	[31]	
11	Sharma et al (2013) [32]	Malaria suspected	5–60*	NA	2251	147	129	1974	1	XE-2000i	microscope	[32]	
12	Sunilkumar et al (2016) [33]	Febrile patients	1–65*	NA	940	40	24	867	9	XN 1000	microscope	[33]	
13	Yasuda et al (2022) [25]	Malaria suspected	NA	NA	80	32	0	47	1	XN-31	PCR	[25]	
14	Yoo et al (2010) [26]	Patients (asymptomatic)	NA	10,682.3 ± 3,458.2**	1801	191	4	1384	222	XE-2100	PCR	[26]	
15	Zuluaga et al (2021) [27]	Febrile patients	27 (14–44)	3508 (886–10613)	1726	513	2	1154	57	XN-31	PCR	[27]	
Note: NA, not applicable; PCR: Polymerase chain reaction; TP, true positive; FP, false positive; FN, false negative; TN: True negative; MI-RBC: Malaria infected red blood cell; Diff-WBC: Differential white blood cell; IQR: Inter quartile range.

NB; a or b: Indicates in one study compare 2 types of symex hematology analyzer; NA: Indicates the result not available;

*: Indicates the result reported by range;

**: Indicates the result reported by mean and standard deviation.

Data quality assessment

The risk of bias in patient selection was rated as low in six of the fifteen diagnostic studies and high in two of the fifteen studies. In the applicability concern domain, there was no high risk of bias in patient selection. The risk of bias in flow and timing was assessed as low in the nine studies (Fig 2).

10.1371/journal.pone.0296766.g002 Fig 2 Risk of bias graph of studies included in the meta-analysis.

Diagnostic accuracy of Sysmex hematology analyzer

The systematic review and meta-analysis comprised fifteen studies to evaluate the diagnostic accuracy of Sysmex hematology analyzer. For those studies, the sensitivity and specificity ranged from 46% to 100% and 81% to 100%, respectively. For those investigations, the summary estimates of sensitivity and specificity of Sysmex hematology analyzer were 95% (95%, CI: 85% -99%) and 99% (95%, CI: 97% -100%), respectively. Sysmex hematology analyzer had a DOR of 1890 (95% CI: 392–9112), a positive likelihood ratio (LR+) of 94.1 (95% CI: 34.6–256.1), and a negative likelihood ratio (LR-) of 0.05 (95% CI: 0.03–0.07). The area under curve (AUC) was 1.00 (95% CI: 0.99–1.00), indicating that the test had excellent diagnostic accuracy (Fig 3).

10.1371/journal.pone.0296766.g003 Fig 3 Forest plot of Sysmex hematology analyzer for malaria detection.

Sub group analysis

Studies conducted to assess Sysmex hematology analyzer accuracy revealed significant heterogeneity (Q = 416.938, I2 = 100, and P< 0.01). Sub-group analysis was performed based on continent, publication year, study design, study population, reference tests, Sysmex hematology analyzer types, and malaria detection parameters. Pooled sensitivity in febrile patients was 92% (95% CI: 65%, 99%), while pooled sensitivity in malaria suspected patients was 97% (95% CI: 82%, 99%). When PCR was employed as a reference test, Sysmex hematology analyzer had sensitivity and specificity of 98% (95% CI: 83, 100) and 99% (99, 100), respectively. When the microscope test was used as the gold standard, the sensitivity and specificity of Sysmex hematology analyzer were 82% (95% CI: 44%, 96%) and 97% (95% CI: 89%, 99%), respectively. The sensitivity of the Sysmex hematology analyzer XN series was 98% (90%, 99%), while the sensitivity of the Sysmex hematology analyzer XE series was 83% (95%CI: 44%, 97%) using of PCR and microscope as gold standard. The threshold effect and meta-regression were used to investigate the cause of heterogeneity. There was no threshold effect between Asian studies (P = 0.19), between 2016 and 2020 (P = 0.28), febrile patients (P = 0.07), Sysmex hematology analyzer with microscope (P = 0.32), Sysmex hematology analyzer XE series (P = 0.33), mi-RBC (P = 0.21), and diff-WBC (P = 0.38) (Table 2).

10.1371/journal.pone.0296766.t002 Table 2 Subgroup analysis of Sysmex hematology analyzer.

Sub group	No. of studies	Pooled sensitivity (95%CI)	Pooled specificity (95%CI)	Heterogeneity test (I2)	P-value	
Continent	Africa	5	99%(75%, 100%)	99% (0.97%, 100%)	97%	< 0.01*	
Asia	6	86% (62%, 96%)	99% (94%, 100%	99%	0.19	
Total pooled	11	94% (79%,98)	99 (97%, 100%)	99%	<0.01*	
Publication year	≤ 2015	4	83% (44%, 97%)	99% (91%, 100%)	99%	0.33	
2016–2020	5	95% (75%, 99%)	99% (92%, 100%)	95%	0.28	
2021–2023	6	97% (55%, 100%)	99% (97%, 100%)	98%	< 0.01*	
Total pooled	15	95% (85%, 99%	99% (97%, 100%)	100%	< 0.01*	
Study design	Cross sectional	10	87% (63%, 96%)	99% (97%, 100%)	98%	0.04*	
Prospective	4	99% (45%, 100%)	98% (95%, 100%)	98%	< 0.01*	
Total pooled	14	94% (77%, 99%)	99% (98, 100%)	99%	< 0.01*	
Population	Febrile patient	4	92% (65%, 99%)	99% (98%, 100%)	91%	0.07	
Malaria suspected	9	97% (82%, 99%)	98% (95%, 99%)	93%	0.04*	
Total pooled	13	96%(85%, 99)	98% (97%, 99%)	95%	0.03*	
Reference tests	PCR	9	98% (83, 100)	99 (99, 100)	99%	< 0.01*	
Microscope	6	82% (44%, 96%)	97% (89%, 99%	99%	0.32	
Total pooled	15	95% (85%, 99%	99% (97%, 100%)	100%	< 0.01*	
Sysmex hematology analyzer types	XN series	11	98% (90%, 99%)	99% (98%, 100%)	98%	0.02*	
XE series	4	83% (44%, 97%)	99% (91%, 100)	99%	0.33	
Total pooled	15	95% (85%, 99%	99% (97%, 100%)	100%	< 0.01*	
Parameters	mi-RBC	10	96% (77%, 99%)	99% (98%, 99%)	97%	0.21	
Diff WBC	5	86% (56%, 97%)	98% (86%, 100%)	99%	0.38	
Total pooled	15	95% (85%, 99%	99% (97%, 100%)	100%	< 0.01*	
Note;

*statistically significant.

The meta-regression of those studies revealed that the most significant sources of heterogeneity (P<0.05) were the reference test, Sysmex hematology analyzer types, and malaria detection parameters (Table 3).

10.1371/journal.pone.0296766.t003 Table 3 Meta-regression analysis of diagnostic accuracy.

Variables	Coefficient	Standard error	p-value	RDOR	95%CI	
Ste	6.12	1.41	<0.01	NA	NA	
S	0.43	0.12	0.03	NA	NA	
Study population	-0.08	0.76	0.89	0.65	0.12–5.31	
Sample size	−1.45	0.57	0.03*	0.49	0.02–0.94	
Reference test	1.09	0.3541	0.04*	2.15	1.19–19.03	
Sysmex hematology analyzer types	1.67	0.5436	0.02*	3.46	1.32–15.91	
Parameters	1.81	0.6310	0.01*	4.29	1.61–19.67	
*statistically significant NA, not applicable; CI, confidence interval; RDOR, relative diagnostic odds ratio; Ste, constant term in the equation; S, a measure of threshold.

Sysmex hematology analyzer with PCR and microscope as reference test

The sensitivity and specificity of Sysmex hematology analyzer performed with PCR as a reference test were varies from 46%-100% and 92%-100%, respectively. Six of the studies (66.7%, 6/9) demonstrated a sensitivity of 90% and more. Eight (88.9%, 8/9) studies showed a specificity ≥95%. The sensitivity and specificity of Sysmex hematology analyzer done with microscope as reference test ranges from 69%–99% to 81%–100%, respectively. Two (2/6) studies showed a sensitivity ≥90%. Three (50%, 3/6) studies showed a specificity ≥95% (Fig 4).

10.1371/journal.pone.0296766.g004 Fig 4 Forest plot of Sysmex hematology analyzer with PCR and microscope as reference test.

The summary estimate of sensitivity and specificity of Sysmex hematology analyzer were 97.6% (95% CI: 83.2, 99.7) and 99.4% (95% CI: 98.5, 99.8), respectively, using PCR as reference test. It had a DOR of 7880.01 (95% CI: 791.03, 78498.74), a positive likelihood ratio (LR+) of 186.87 (95% CI: 67.93, 514.07), and a negative likelihood ratio (LR-) of 0.023 (95% CI: 0.003, 0.188). The area under the curve was 1.00 (95% CI: 0.99–1.00), indicating that the test had excellent diagnostic accuracy (Fig 5).

10.1371/journal.pone.0296766.g005 Fig 5 Summary receiver operating characteristic plot of sensitivity and specificity of Sysmex hematology analyzer with PCR as a reference test.

Sysmex hematology analyzer with microscope as reference

The summary estimate of sensitivity and specificity of employing a microscope as the gold standard method were estimated to be 81.7% (95% CI: 44%, 96) and 97.02% (95% CI: 88.92, 99.7), respectively. With a microscope as the gold standard, the diagnostic odds ratio, LR+, and LR- of Sysmex were 146.27 (95% CI: 29.86, 716.4), 27.50 (95% CI: 8.03, 94.20), and 0.188 (95% CI: 0.046, 0.763), respectively. The AUC was 0.98 (95% CI: 0.96–0.99), indicating that the test had excellent diagnostic accuracy (Fig 6).

10.1371/journal.pone.0296766.g006 Fig 6 Summary receiver operating characteristic plot of sensitivity and specificity of Sysmex hematology analyzer with microscope as a reference test.

Publication bias

The Deeks’ funnel plot asymmetry test of DOR revealed no significant asymmetry (P = 0.14), indicating that there was no observable publication bias (Fig 7).

10.1371/journal.pone.0296766.g007 Fig 7 Publication bias of Sysmex hematology analyzer for diagnostic accuracy.

Discussion

An accurate and timely diagnosis is critical for managing, controlling, and eradicating malaria. Early malaria diagnosis is necessary to guide adequate treatment and decrease the severe effects of infection [1]. Lack of clinical and laboratory experience, prolonged incubation periods and Plasmodium vivax relapses [34,35], or prophylaxis in travellers can all delay diagnosis, increasing the risk of malaria-related complications [36]. An accurate malaria detection technology integrated into the routine Sysmex hematology analyzer could assist detect infections earlier and potentially reduce complications of malaria associated with malaria infection. It also utilized by minimally trained personnel, does not require sample preparation, has no observer-dependent variability, and is available in the hospital and health center. Another significant advantage of the Sysmex hematology analyzer automation is that it delivers a CBC with each assay, integrating malaria diagnosis and treatment [15].

All accessible studies, both symptomatic and asymptomatic, were extensively searched. The majority of these investigations were undertaken after 2015; only one study was conducted before 2010, reflecting the relatively recent interest in this diagnostic approach. The I2 statistic was used for investigating statistical heterogeneity, which reflects variance across studies due to inter-study variability. Heterogeneity was expected to be associated with the test reading method, the level of parasitaemia, and the comparators. There was significant heterogeneity among the studies included in this meta-analysis. Meta-regression analysis for the Sysmex hematology analyzer revealed that the gold standard reference test, the Sysmex hematology analyzer types and parameters for malaria detection were the sources of heterogeneity.

The overall estimated sensitivity and specificity of Sysmex hematology analyzer were 95% (95%CI: 85–99%) and 99% (95%CI: 97%-100%), respectively, according to this review. The Sysmex hematology analyzer had high diagnostic accuracy (AUC: 1.00 (95% CI: 0.99–1.00). Sysmex hematology analyzer had 1890 (95% CI 392–9112) times higher odds of obtaining a positive result in a diseased person than in a non-diseased one. On the other hand, it showed 94.1 (95% CI: 34.6–256.1) times higher odds of a positive individual and a negative one. Therefore, the Sysmex hematology analyzer is employed as an alternative diagnostic tool for malaria, given its high diagnostic accuracy.

This review’s pooled sensitivity was higher than the sensitivity of studies on RDT diagnostic accuracy (42% for conventional vs. 61% for ultrasensitive RDT) [37], while another study revealed lower sensitivity (44.3% for conventional and 56.1% for high sensitive RDT) [38]. The reduced sensitivity of RDT may be attributed to asymptomatic malaria and deletions of the Plasmodium falciparum gene encoding the target histidine rich protein 2/3 (HRP2/3). The microscopic diagnosis of malaria tends to be less sensitive in low parasitaemia and has been reported as 70% in pregnancy-associated malaria [39]. It could be because microscopes require expert laboratory personnel, have limited diagnostic accuracy, and generate false negative results in asymptomatic malaria. This review’s pooled sensitivity was consistent with a systematic review and meta-analysis of the diagnostic accuracy of loop-mediated isothermal amplification (LAMP) techniques, which indicated a sensitivity of 97% [40] and another review, which reported the sensitivity of PCR to be 98% [41]. The pooled specificity of Sysmex hematology analyzer had high specificity in this review and was almost identical to the specificity of RDT [37], microscope [39], LAMP [40] and PCR [41].

In this review, Sysmex hematology analyzer with PCR as the gold standard was shown to have a higher pooled sensitivity than Sysmex hematology analyzer with microscopy as gold standard (97.6% (95% CI: 83.2–99.7%) vs. 81.7% (95% CI: 44%, 96). However, the overall estimate of specificity of Sysmex hematology analyzer using PCR as the reference method and Sysmex hematology analyzer utilising microscopy as the gold standard method had comparable specificity (99.4% (95% CI: 98.5, 99.8) vs. 97.02% (95% CI: 88.92%, 99.7%), respectively. Also, the diagnostic accuracy of Sysmex hematology analyzer with PCR as gold standard and Sysmex hematology analyzer with microscope was almost similar (AUC: 1.00 (95% CI: 0.99–1.00) vs. 0.98 (95% CI: 0.96–0.99)), respectively.

The sensitivity of Sysmex hematology analyzer with PCR as gold standard was greater in this review than a systematic review and meta-analysis study on microscope with PCR in Ethiopia, which showed a sensitivity of 75.20% [18], and another review in Colombia, which stated a sensitivity of 70.8% [39]. In the other hand, the specificity of this study was nearly identical to that of a studies on microscopy with PCR in Ethiopia (97.12%) [18] and Colombia (99%) [39]. The summary estimates of sensitivity this review higher than the review done about RDT with PCR in Ethiopia were 66.18% [18]. In contrast, the summary estimations of specificity of this review were similar to review done in Ethiopia (95.36%) [18]. This review’s sensitivity was almost identical to that of a study on LAMP using PCR as gold standard (97%) [40].

The sensitivity of Sysmex hematology analyzer with microscope as reference test was lower in this review than in a systematic review and meta-analysis study on RDT with microscope in Ethiopia (95.05%) [18] and India (97.0%) [42]. The lower sensitivity for this review could be attributed to the fact that the majority of the studies used differential WBC scatter for malaria diagnosis. According to a review of haematology analyzers for malaria detection, the decrease in sensitivity for differential WBC abnormalities could be due to the lack of a consensus definition for this diagnosis criterion, as well as difficulty and subjectivity in manually evaluating these patterns, which could have resulted in a classification bias. However, the specificity of this study was nearly same to that of review conducted in Ethiopia (96.47%) [18] and India (96.0%) [42].

The sensitivity of Sysmex hematology analyzer XN series was higher compared to XE series (98% vs. 83%), respectively in this review. The Sysmex hematology analyzer XN series and XE series types had similar specificity (99%). Both Sysmex hematology analyzer XN series and XE series types had excellent diagnostic accuracy (AUC: 0.99 (95%CI: 0.99–1.00) vs. 0.99 (95%CI: 0.97–0.99)).

In this review, the sensitivity of Sysmex hematology analyzer by using malaria infected RBC for malaria detection was higher than the use of diff WBC (96% vs. 86%), respectively. The Sysmex hematology analyzer using mi-RBC and diff-WBC for malaria detection had almost similar specificity (99% vs.98%), respectively. Generally, both Sysmex hematology analyzer with mi- RBC and diff- WBC techniques had excellent diagnostic accuracy (AUC: 0.99 (95%CI: 0.98–1.00) vs. 0.98 (95%CI: 0.96–0.99)).

Conclusion

Sysmex hematology analyzer had high summary estimate of sensitivity and specificity. The pooled sensitivity was higher for Sysmex hematology analyzer using PCR as the gold standard than for Sysmex hematology analyzer using a microscope as the gold standard. As a result, Sysmex hematology analyzer is used as an alternate diagnostic tool for malaria diagnosis in malaria endemic area and non-endemic area due to its high diagnostic accuracy. The Sysmex hematology analyzer boasts numerous implications. It enabling the detection of parasites in both endemic and non-endemic areas. Furthermore, it is capable of simultaneously providing CBC results, identifying parasites even at low concentrations, and identifying different stages of the parasite. the ability to quantify parasite density and monitor treatment response. The analyzer requires minimal training, does not require sample preparation, has no observer-dependent variability and comes at a cost comparable to that of performing a CBC. Additionally, it can be utilized in blood banks to screen for malaria. However, its application in rural settings or post-health care scenarios presents challenges, as it necessitates stable electricity and a reliable supply of reagents, making it difficult to replace RDTs in these specific contexts.

Supporting information

S1 File PRISMA checklist for “Diagnostic role of Sysmex hematology analyzer in the detection of malaria: A systematic review and meta-analysis.

(DOCX)

The authors would like to express their gratitude to the authors of the included research as well as the participants in their investigations.

Abbreviations

AUC Area Under Curve

CBC Complete Blood cell Count

DOR Diagnostic Odd Ratio

LAMP Loop-mediated isothermal Amplification

MI-RBC Malaria Infected Red Blood Cell

PCR Polymerase-Chain-Reaction

RDT Rapid Diagnostic Test

WBC White Blood Cell

WHO World health organization

10.1371/journal.pone.0296766.r001
Decision Letter 0
Agaba Bosco Bekiita Academic Editor
© 2024 Bosco Bekiita Agaba
2024
Bosco Bekiita Agaba
https://creativecommons.org/licenses/by/4.0/ 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.
Submission Version0
15 Nov 2023

PONE-D-23-30250Diagnostic role of Sysmex hematology analyzer in the detection of malaria: A systematic review and meta-analysisPLOS ONE

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Additional Editor Comments:

General:

Can one load a blood sample to test for malaria only? Or one has to run a CBC to look for parasites alongside a CBC?

What happens when a patient only wants malaria test alone, or if this is not possible, What’s the economic implication if one has to run a malaria test alongside a CBC for malaria patients?

At what level of care within the system would the equipment be suitable for optimal utilization?

Despite the challenges faced by RDTs, they are easy to use and can be used by all cadres as POCs including nurses, Lab techs, etc hence increasing access to parasite-based diagnosis; based on this, What would be health cadre to use this technology for malaria diagnosis in terms qualification (scientists, Lab techs, nurses or other cadres trained to test for malaria) and how does this affect access to testing and affect the equipment advantage?

Were these mostly done in Africa where the malaria burden is, what was the distribution of the reviewed studies?

How many types or versions of sysmex equipment are able to do malaria testing? Did the studies cover all versions or one equipment version and what’s the implication?

What patient populations (symptomatic, asymptomatic, age, parasite densities, etc, could u provide a table summarizing patient baseline characteristics?

Line: 108: revise the sentience- uantity?

Line 132-33: How many non-English articles/studies were excluded? Unpublished reports and conference papers?

Line 159: whats the authors comment on using a sample of 15 papers for a systematic review to draw the conclusions?

Line 165-67: what was the reference/gold standard?

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

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The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

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Reviewer #2: Yes

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**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: General comments:

-The study's objective is to assess Sysmex's diagnostic performance in diagnosing malaria; however, the cost was not considered by the authors. Cost is quite important, particularly in areas where malaria is a major problem.

-Where this device will be used was not specified by the authors. Is it in the comprehensive hospital, primary hospital, or health center? Can this device be used in health post-level settings to replace the existing RDT?

-The authors advised to revise the conclusion section. The conclusion fails to persuade the readers based on the findings.

-Apart from PCR, the diagnostic performance of LAMP is extensively studied and recommended by most scientists in the fields. Nevertheless, the authors didn't mentioned about LAMP in the background section.

-Control and eradication were terms employed by the authors in the body of the manuscript. They overlooked a critical step "elimination". The elimination process is crucial to the activities of a particular country or subregional program. For instance, in Ethiopia (where the current program is malaria elimination) or other East African countries where gene deletions are currently highly prevalent, this method may be suggested for the diagnosis of malaria.

-The authors advised italicizing every malaria species mentioned in the text's main body.

-In the background the cost implication of using PCR was not mentioned.

-What more advantages come with using a Sysmex hematological analyzer than those already mentioned?

-The year of studies indicated in the abstract and the paper body are different, so please correct them.

-Table-1 need revisions. It would be nice to include one column for reference.

Specific comments:

-Line 176, in the nine studies are ?? needs revision.

-Line 276. "Because of has high diagnostic accuracy" needs revision.

-Table 2 needs formatting.

-The conclusion must be changed in line with the findings.

Reviewer #2: Please revise grammar and spelling errors, I am listing some here. I have also suggested some options to paraphrase some sentences for clarity.

• 108: uantity =quantity

• 214: significant, confidence

• 237: Sysmex

• 253: malaria-related complications

• 254: into the routine

• 252: plasmodium=Plasmodium

• 255: instead of “negative consequences…” consider “complications of malaria”.

• 256: not requires = does not require

• 264: associated with

• 265: consider replacing “ the patient, parasitaemia “ with “ the level of parasitaemia”.

• 266-267: consider replacing “for Sysmex hematology analyzer” with “for the Sysmex hematology analyzer ..”

• 269: estimate sensitivity =estimated sensitivity

• 272-273: obtaining a positive result in a diseased person than in a non-diseased one

• 274: a positive individual and a negative one

• 276:” diagnosis. Because” = ” diagnosis because”

• 282-283: “diagnostic accuracy ….” This sentence is not clear , consider replacing it with “ the microscopic diagnosis of malaria tends to be less sensitive in low parasitaemia and has been reported as 70% in pregnancy-associated malaria [36].

• 287-288: “which stated a sensitivity…” consider “ which reported the sensitivity of PCR to be 98%”

• 291: ….the gold standard was shown to have a higher ….

Reviewer #3: The manuscript followed sound methodological and statistical strategies, but has some typological and grammatical errors that need to be corrected to make it clear and easy to read. The discussion did not include the "and so what" of their findings and the implications of the findings.

**********

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Reviewer #1: Yes: Adugna Abera

Reviewer #2: Yes: AHMED A. ADEEL

Reviewer #3: Yes: Dr. Alberta Amu

**********

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Attachment Submitted filename: PONE-D-23-30250_reviewer AA edits.pdf

10.1371/journal.pone.0296766.r002
Author response to Decision Letter 0
Submission Version1
23 Nov 2023

We tried to corrected the comments and incorporated in the manuscript

Attachment Submitted filename: Response to Reviewers.docx

10.1371/journal.pone.0296766.r003
Decision Letter 1
Agaba Bosco Bekiita Academic Editor
© 2024 Bosco Bekiita Agaba
2024
Bosco Bekiita Agaba
https://creativecommons.org/licenses/by/4.0/ 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.
Submission Version1
18 Dec 2023

Diagnostic role of Sysmex hematology analyzer in the detection of malaria: A systematic review and meta-analysis

PONE-D-23-30250R1

Dear Dr. Zewudu Mulatie ,

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Reviewer #1: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

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The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #3: (No Response)

**********

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Reviewer #3: (No Response)

**********

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Reviewer #1: Yes

Reviewer #3: (No Response)

**********

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Reviewer #3: Yes: Dr. Alberta Amu

**********

10.1371/journal.pone.0296766.r004
Acceptance letter
Agaba Bosco Bekiita Academic Editor
© 2024 Bosco Bekiita Agaba
2024
Bosco Bekiita Agaba
https://creativecommons.org/licenses/by/4.0/ 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.
20 Jun 2024

PONE-D-23-30250R1

PLOS ONE

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==== Refs
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