Screening for platelet function disorders with Multiplate and platelet function analyzer

Figures & data

Table I. Definitions of platelet function disorders (LTA) and Multiplate/PFA abnormalities.

	Gold standard: LTA (AA, TRAP, ADP, COL, EPI, RIST)	Screening test: Multiplate (ASPItest, TRAPtest, ADPtest, COLtest)	Screening test: PFA-200 (C-EPI and C-ADP)
Platelet function defect/abnormal test result	≥2 agonist abnormalities, or only COL4/RIST* abnormal	≥1 agonist abnormalities**	At least one kit prolonged***
No platelet function defect/normal test result	<2 agonist abnormalities (except for only COL4/RIST*)	No agonist abnormality	No kit prolonged

Legend: the diagnostic performance of the screening tests Multiplate and PFA, using predefined cutoff levels, was calculated using cross-tables designed as this table.

*For comparison of LTA-Multiplate, patients with only LTA RIST abnormalities were not considered, as GP1b function cannot be assessed by current Multiplate agonists. **Reference values for Multiplate agonists: AUC < 33 for ADP, <50 for AA, <70 for TRAP, and <45 for COL.

***Reference values for PFA kits: CT > 160 s for C-EPI; CT > 118 s for C-ADP.

Abbreviations: AA, arachidonic acid; ADP, adenosine diphosphate; AUC, area under the curve; COL, collagen; CT, closure time; EPI, epinephrine; LTA, light transmission aggregometry; PFA, platelet function analyzer; TRAP, thrombin receptor activatable peptide; RIST, ristocetin.

Table II. Patient characteristics.

N = 414	Preoperative patients n (%), mean ± SD	Patients referred for bleeding evaluation n (%), mean ± SD	Patients with a diagnosed bleeding disorder n (%), mean ± SD
Number	335	54	25
Age	52 ± 15	46 ± 16	50 ± 13
Female	216 (64.5)	41 (76)	11 (44)
Hematocrit (L/L)
Women	0.41 ± 0.03	0.42 ± 0.03	0.43 ± 0.04
Men	0.45 ± 0.03	0.44 ± 0.05	0.45 ± 0.04
Platelets (10^9/L)	270 ± 64	269 ± 73	239 ± 64
MPV	10.6 ± 0.87	10.5 ± 1.1	10.4 ± 1.1
PFDs	16 (4.8)	10 (18.5)	3 (12)

Abbreviations: MPV, mean platelet volume; LTA, light transmission aggregometry; PFD, platelet function disorder; SD, standard deviation.

Table III. Multiplate and PFA results regarding the detection of PFDs on LTA.

a. Preoperative patients	LTA abnormal*	LTA normal	Total	Diagnostic performance % (95%CI)
Multiplate abnormal**	1	9	10	Sensitivity = 6.3 (0-30)
Multiplate normal	15	292	307	Specificity = 97 (94-99)
Total	16	301	317	PPV = 10 (0-45)
				NPV = 95 (92-97)

b. Preoperative patients	LTA abnormal*	LTA normal	Total	Diagnostic performance % (95%CI)
PFA abnormal***	0	33	33	Sensitivity = 0 (0-21)
PFA normal	16	266	282	Specificity = 89 (85-92)
Total	16	299	315	PPV = 0 (0-11)
				NPV = 94 (91-97)

c. Referred patients	LTA abnormal*	LTA normal	Total	Diagnostic performance % (95%CI)
Multiplate abnormal**	4	1	5	Sensitivity =40 (12-74)
Multiplate normal	6	39	45	Specificity = 98 (87-99.9)
Total	10	40	50	PPV = 80 (28-99)
				NPV = 87 (73-95)

d. Referred patients	LTA abnormal*	LTA normal	Total	Diagnostic performance % (95%CI)
PFA abnormal***	2	7	9	Sensitivity =22 (2.8-60)
PFA normal	7	32	39	Specificity = 82 (66-92)
Total	9	39	48	PPV = 22 (2.8-60)
				NPV = 82 (66-92)

Legend: Table A; two-by-two table with diagnostic performance of Multiplate in preoperative patients. Table B; two-by-two table with diagnostic performance of PFA in preoperative patients. Table C; two-by-two table with diagnostic performance of Multiplate in patients referred for bleeding evaluation. Table D; two-by-two table with diagnostic performance of PFA in patients referred for bleeding evaluation.*≥2 abnormal LTA curves, **≥1 Multiplate agonist with low AUC, ***CT EPI and/or ADP prolonged

Abbreviations: ADP; adenosine diphosphate. AUC; area under the curve. CI; confidence interval. CT; Closure time. EPI; epinephrine. LTA; light transmission aggregometry. NPV; negative predictive value. PFA; platelet function analyzer. PPV; positive predictive value.

Figure 1. Diagnostic performance of the Multiplate and PFA for detection of PFDs. Legend: Sensitivity and specificity of the Multiplate and PFA when using predefined cutoff levels in three patient groups, using the presence of PFDs as detected by the LTA as reference. For these calculations, the Multiplate was considered abnormal in case of ≥1 agonist abnormalities, and the PFA was considered abnormal in case of one or two prolonged PFA CTs (see Table 1). Abbreviations: FN, false negative. FP, false positive. PFA, platelet function analyzer. TN, true negative. TP, true positive.

Table IV. Performance of Multiplate agonists compared to corresponding LTA agonists as reference test.

Multiplate agonists	LTA agonists	Preoperative patients AUC (95%CI), p-value	Patients referred for bleeding evaluation AUC (95%CI), p-value	Patients with a diagnosed bleeding disorder AUC (95%CI), p-value
ASPItest	AA	0.71 (0.49–0.92), p = 0.05	0.54 (0.28–0.80), p = 0.73	0.86 (0.65–1.00), p = 0.02
TRAPtest	TRAP	0.57 (0.36–0.78), p = 0.49	0.72 (0.45–0.99), p = 0.08	0.83 (0.52–1.00), p = 0.05
COLtest	COL*	0.59 (0.46–0.73), p = 0.20	0.50 (0.25–0.75), p = 0.99	0.70 (0.38–1.00), p = 0.24
ADPtest	ADP **	0.63 (0.51–0.75), p = 0.03	0.52 (0.31–0.73), p = 0.87	1.00 (1.00–1.00), p = 0.01

Legend: AUC with 95%CI derived from ROC curves of Multiplate agonists and corresponding LTA agonists.

*In case of COL1 and/or COL4 abnormality.

**In case of ADP5 and/or ADP10 abnormality

Abbreviations: AA/ASPI, arachidonic acid; ADP, adenosine diphosphate; AUC, area under the curve; CI, confidence interval; COL, collagen; LTA, light transmission aggregometry; PFA, platelet function analyzer; TRAP, thrombin receptor activatable peptide.

Table V. Performance of PFA kits compared to corresponding LTA agonists as reference test.

PFA kits	LTA agonists	Preoperative patients AUC (95%CI), p-value	Patients referred for bleeding evaluation AUC (95%CI), p-value	Patients with a diagnosed bleeding disorder AUC (95%CI), p-value
C-ADP	COL*	0.50 (0.36–0.63), p = 0.96	0.44 (0.24–0.64), p = 0.59	0.92 (0.77–1.00), p = 0.08
C-EPI	COL*	0.59 (0.48–0.71), p = 0.22	0.51 (0.28–0.74), p = 0.94	0.92 (0.77–1.00), p = 0.08
C-ADP	ADP **	0.41 (0.30–0.51), p = 0.12	0.36 (0.15–0.56), p = 0.18	1.00 (1.00–1.00), p = 0.01
C-EPI	EPI	0.47 (0.18–0.75), p = 0.82	0.51 (0.27–0.74), p = 0.96	0.74 (0.33–1.00), p = 0.14

Legend: AUC with 95%CI derived from ROC curves of PFA kits and corresponding LTA agonists.

*In case of COL1 and/or COL4 abnormality.

**In case of ADP5 and/or ADP10 abnormality.

Abbreviations: ADP, adenosine diphosphate; AUC, area under the curve; C, cartridge; CI, confidence interval; COL, collagen; EPI, epinephrine; LTA, light transmission aggregometry; PFA, platelet function analyzer; TRAP, thrombin receptor activatable peptide.