R.Li, C.Swaelens, F.Vandermijnsbrugge, B.Cantinieaux BSTH Laboratory of haematology, Porte de Hal, Antwerp

Institut Jules Bordet and CHU Saint-Pierre, ULB 23/11/2012

Normal aPTT with Actin-FS avoids intrinsic pathway factors assays in the presence of an isolated prolongation of aPTT (Platelin-LS)

without hemorrhagic history

Institut J. Bordet

Introduction

Reagent Platelin-LS

Coagulometer MDA II aPTT assays

Lupus anticoagulant LA Heparin therapy

Intrinsic pathway factor deficiency

Sensitivity

Introduction

An isolated prolonged

aPTT paediatric

Pre-operative screening

Bleeding related

Non-bleeding related

FVIII, FIX, FXI deficiency

FXII or contact factor

deficiency, Inhibitor like

LA

Introduction

aPTT with Actin FS

An isolated prolonged

aPTT with

Platelin LS

Normal aPTT

Prolonged aPTT

A mixing aPTT study

Corrected aPTT

Non corrected

aPTT

FVIII, FIX, FXI FXII deficiency

LA FXII deficiency

LA

FVIII, FIX, FXI, FXII deficiency

Aim

aPTT with

Actin FS An isolated

prolonged aPTT with

Platelin LS A mixing aPTT study

Non-bleeding related

FXII or contact factor deficiency,

Inhibitor like LA

Bleeding related

FVIII, FIX, FXI deficiency

Differential diagnosis

An algorithm for a prolonged aPTT

Prothrombin time, Fibrinogen and Thrombin time

At first time a prolonged

aPTT with Platelin LS

Abnormal PT, Fibrinogen and TT

Normal PT, Fibrinogen and TT

New sample to confirm this prolonged aPTT and to continue further investigations

aPTT with Actin FS and

A mixing aPTT (1:1 without incubation)

Follow other algorithms

Materials and Methods

�  The quantitative determinations of FVIII, FIX, FXI and FXII were performed

in using one stage factor clotting assay in the week. - firstly with Platelin LS in two dilutions,

- secondly with Actin FS if a suspicion of a nonspecific inhibitor detected

by Platelin LS with a non-parallel curve.

�  LA assays (PTT-LA and dRVVT) were done in the week.

Materials and Methods �  During 4 years, from 2008 to 2011,

among 9048 paediatric patients: an isolated prolonged aPTT in 308 (3.4%) outpatients in their haemostasis’ screening before surgical intervention

�  156 pateints with 161 samples: confirmed this prolongation of aPTT

Median age: 3 years-old, 1 to 15 years-old

including 13 neonatal samples (age < 6 months) �  Further investigations including :FVIII, FIX, FXI, FXII and LA

with the limitation of the plasma volume

-- in 140 samples: FVIII, FIX and FXI were performed

-- in 131 samples : FVIII, FIX, FXI and FXII were performed -- in 88 samples: LA assays were performed

Materials and Methods �  cut-off values

-- aPTT with Platelin LS, aPTT with Actin FS and mixing aPTT cut-off values were established locally (N=50).

-- FVIII, FIX, FXI and F XII

50 % – 200%

-- LA cut-off values were established according to the international recommendation

�  Statistics

Sensitivity, Specificity, Postive Predicitive Value, Negative Predictive Value and

p value were analysed by Fisher’s exact test

Results With the further investigation of factor clotting and LA assays : Explanation of the prolonged aPTT: 101/161 (63%)

�  Factor deficiencies: 43 -- for FVIII, FIX and FXI: 17/140 (12%) -- isolated : 10 -- multiple deficiencies: 7 (5 neonatal cases) -- for FVIII, FIX, FXI and FXII: 31/131 (24%) -- isolated FXII: 26 -- multiple deficiencies : 5 (3 neonatal cases) �  LA: 88

-- Positive: 64 /88 (73%) -- Negative: 24

Results

N=140 (FVIII, FIX and FXI ) Factor Deficiencies (N=17)

% Sensitivity Specificity PPV NPV P value

Prolonged Actin-FS 59 93 53 94 <0,0001

Corrected mixing aPTT 59 29 10 84 0,2328

Prolonged Actin-FS and

Corrected mixing aPTT 29 96 50 91 0,0025

Table 1 The statistical values of an aPTT with Actin FS and a mixing aPTT study for the detection of FVIII, FIX or FXI deficiencies by Fisher’s exact test.

N=140 (FVIII, FIX and FXI )

Bleeding related

Non-bleeding related

N=17 FVIII, FIX, FXI

deficiencies

N=123 FVIII, FIX, FXI

normal

Results

Table 2 The statistical values of an aPTT with Actin FS and a mixing aPTT study for the detection of FVIII, FIX , FXI or FXII deficiencies by Fisher’s exact test.

N=131 (F VIII, IX, FXI and XII ) Factor Deficiencies (N=43)

% Sensitivity Specificity PPV NPV P value

Prolonged ActinFS 28 92 63 72 0,0034

Corrected mixing aPTT 74 38 37 75 0,1225

Prolonged ActinFS and

Corrected mixing aPTT 14 95 60 69 0,0634

N=131 (FVIII, FIX, FXI and FXII)

N=43 FVIII, FIX, FXI, FXII

deficiencies

N=88 FVIII, FIX, FXI, FXII

normal

Results Table 3. The levels of intrinsic pathway factor deficiencies with normal Actin FS

  Normal Actin FS Factor Deficiencies 16,4-36,2 F VIII F IX F XI F XII

  secondes % % % % Case 1 33,8 48 Case 2 30,4 41 Case 3 32,7 46 Case 4 33,1 37 Case 5 32,1 38 Case 6 35,4 43 Case 7 34,1 32   24 of 26 cases (92%) normal 22 - 48

Results

N= 88 (LA) Positive LA (N=64)

% Sensitivity Specificity PPV NPV P value

Non-corrected mixing aPTT 55 88 92 42 0,0003

Normal Actin-FS 94 21 76 56 0,0584

Non-corrected mixing aPTT

and normal Actin-FS 50 96 97 42 <0,0001

Table 4. The statistical values of an aPTT with Actin-FS and a mixing aPTT study for the LA detection.

A prolonged aPTT with Actin FS was found in 4 of 64 positive LA samples.

N=88 (LA)

N=64 Positive LA

N=24 Negative LA

Conclusions

Face to an isolated prolongation of aPTT without hemorrhagic or family history,

�  A normal aPTT with Actin-FS permitted: -- to exclude a FVIII, FIX or FXI deficiency lower than 30%,

-- to explain an isolated prolonged aPTT (Platelin-LS)

by either a FXII deficiency or the presence of LA ,

so it was not necessary to perform the factor clotting assays in this case. �  A mixing aPTT study

-- a non-corrected mixing aPTT was useful to suggest the presence of LA,

-- a corrected mixing aPTT was useless to detect a factor deficiency.