Abstract Number: PB0921
Meeting: ISTH 2021 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » VWF and von Willebrand Factor Disorders - Clinical Conditions
Background: Bleeding time (BT) and PFA (Platelet Function Analyser)-100/200 are screening tests for primary hemostatic disorders. The diagnosis of von Willebrand disease (VWD) in low- and medium-income countries (LMIC) is challenging due to cost and lack of laboratory infrastructure. Since PFA-100/200 is expensive, BT is the only screening test for VWD diagnosis in most laboratories in LMIC.
Aims: To determine the diagnostic performance of ISTH Bleeding assessment tool (BAT), BT and PFA-200 in the diagnosis of VWD in a tertiary centre in South India
Methods: This was a retrospective study of VWD patients who presented to a tertiary hospital in South India from January 2012 to March 2019. 188 consecutive patients with no intrinsic abnormality were included as controls. Final diagnosis was made after correlating with history and laboratory tests including BT, PFA-200 with Collagen/ADP (PFA-ADP) and Collagen/Epinephrine (PFA-EPI), Activated Partial Thromboplastin time, Factor VIII, Ristocetin cofactor assay (vWF:RCo), Von Willebrand antigen (VWF:Ag), Collagen binding assay (where applicable) and parental evaluation (where applicable) in both patients and controls. Bleeding time was performed only by trained and experienced technical staff.
Results: A total of 444 cases with VWF:Ag <50 U/dL were included in the study. The distribution and results are summarised in Table. The proportion of severe (VWF:RCo <10%), moderate (VWF:RCo 10-30%) and mild (VWF:RCo >30%) was 70%, 19% and 11% respectively. The overall sensitivity/positive predictive value (PPV) of BT and PFA-200 (either COL/ADP or COL/EPI prolonged) was 72.3%/99.6% and 91.8%/96.1% respectively. The sensitivity of each subtype is shown in Figure. There was a good inverse correlation between BT vs VWF:RCo (r=-0.66), PFA-ADP vs VWF:RCo (r=-0.71) and PFA-EPI vs VWF:RCo (r=-0.63).
| Number of cases (%) N=444 |
vWF:RCo (%) Median (IQR) N=444 |
vWF:Ag (U/dL) Median (IQR) N=444 |
Median BAT score (IQR) N=395 |
BT (mins)* Median (IQR) [% with maximal prolongation] N=351 |
PFA-ADP# (s) Median (IQR) [% with maximal prolongation] N=245 |
PFA-EPI CT$ (s) Median (IQR) [% with maximal prolongation] N=251 |
|
| Type 3 VWD | 215 (48.4%) | 0 | 0 | 7 (4-10) | 15 (15 -15) [98%] |
268.5 (227-300) [100%] |
277 (246 – 300) [100%] |
| Type 2 VWD | 123 (27.7%) | 10.4 (0 – 19) |
33.8 (23 – 47) |
4 (2-5) | 9 (4.5 – 15) [35%] |
284 (210 – 300) [90.5%] |
292 (241-300) [92%] |
| Type 1 VWD | 69 (15.5%) | 7 (0-14) |
10.3 (5 – 17) |
4 (3-8) | 8.5 (3.25 – 15) [48%] |
293 (258-300) [87.5%] |
299.5 (262-300) [90.5%] |
| Low VWF:Ag (30-50 u/dL) |
37 (8.3%) |
38.4 (33 – 46) |
42.5 (36 – 46) |
3 (2-4) | 3.25 (2.5 – 4) [0%] |
113 (98 -139) [5%] |
154 (142 -200) [16%] |
Distribution of VWD and summary of laboratory characteristics and BAT score in different subtypes of VWD. *BT reference range (RR) : 2 – 6 minutes, upper limit (UL) 15 minutes; # PFA-ADP RR: 68-142 secs, UL 300 secs; $PFA-EPI RR: 89-167 secs, UL 300 secs
Sensitivity of Bleeding time, PFA-200 and BAT score in VWD classified based on A) subtypes of VWD, and B) severity of VWD.
Conclusions: PFA-200 is very sensitive to VWD. BT has good sensitivity and was comparable to PFA-200 in severe VWD cases. When performed under standardised conditions, BT will help in the evaluation of VWD in LMIC.
To cite this abstract in AMA style:
Geevar T, Gautam Dave R, Vijayan R, Samuel A, Singh S, John Mammen J, Chandran Nair S. Sensitivity of ISTH Bleeding Assessment Tool, Bleeding Time and PFA-200 in the Diagnosis of von Willebrand Disease [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/sensitivity-of-isth-bleeding-assessment-tool-bleeding-time-and-pfa-200-in-the-diagnosis-of-von-willebrand-disease/. Accessed November 28, 2023.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/sensitivity-of-isth-bleeding-assessment-tool-bleeding-time-and-pfa-200-in-the-diagnosis-of-von-willebrand-disease/