Automated haematology analysis to diagnose malaria

Malaria Journal

Table 4 Summary of studies evaluating the malaria diagnostic accuracy of the Sysmex XE-2100 analyser.

First author, year and country	Number of participants and diagnoses	Blinding	Index test criterion		Sensitivity %	Specificity %
Huh, 2008, South Korea [54]	Total: 463, P. vivax: 144	-	>5% pseudoeosinophilia and/or an abnormal DIFF scatter-plot^†		69.4	100
Yoo, 2010, South Korea [55]*	Total: 1801, P. vivax: 413	-			46.2	99.7
Campuzano-Zuluaga, 2010, Colombia [51]	Total: 158, P. falciparum: 30, P. vivax: 65, 63 febrile patients Validation control group including healthy and febrile participants: 161	+	Model ^¶	Variables (Figure 4)
			U-OD_Pv^‡	'XE-2100 P. vivax pattern'	96.9	93.6
			M-OD_Pv**	Number of granulocyte DIFF abnormalities ≥7 pixels in the WBC/BASO(III)	95.4	98.4
			N-OD1_Pv	ΔDIFF/WBC Plateletcrit LYMPH-Y	94.3	95.1
			N-OD2_Pv	PLT-O Pixels WBC/BASO(III)	96.8	96.8
			N-OD1_Pf	PLT-O RDW-SD LYMPH-Y	93	81
			N-OD2_Pf	PLT-O RDW-SD Pixels WBC/BASO(III)	86	90

* All studies use microscopy as reference test for malaria diagnosis, except Yoo and colleagues study that also use real time quantitative PCR (RT-PCR). ^†An abnormal DIFF scatter-plot corresponds to extra blue, red or gray-coded groups in the DIFF scatter-plot (Figure 4). ^¶ All N-OD models use continuous variables and are designed to compute a predicted probability of malaria obtained from the logistic regression analyses as shown in Figure 3. ^‡The recognition of a 'general XE-2100 P. vivax pattern' seen in the DIFF, WBC/BASO and RET-EXT scatter-plots corresponds to the univariate observer-dependent model [U-OD_Pv]. M-OD_Pv: The multivariate observer-depend model, by means of a 'malaria score' quantifies several abnormalities seen in the U-OD_Pv. **P. vivax Malaria Score: '≥7 pixels in the WBC/BASO(III)' (3 points), 'number of granulocyte-coded DIFF abnormalities' (10 variables; 1 point per variable), with ≥4 points being diagnostic. N-OD1: Non-observer dependent models that use built-in XE-2100 variables, for P. vivax (_Pv) and P. falciparum (_Pf). N-OD2: Non-observer dependent models that use built-in XE-2100 variables and the WBC/BASO(III) pixel count (Figure 4), for P. vivax (_Pv) and P. falciparum (_Pf). PLT-O: Optic platelet count. RDW-SD: Red cell distribution width SD.

ISSN: 1475-2875