Abstract Number: PB0890
Meeting: ISTH 2021 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Platelet Function Disorders, Acquired
Background: Aspirin is frequently used for venous thromboembolism (VTE) prophylaxis after total hip and knee arthroplasties (THA/TKA). However, the effectiveness and safety are unknown when used in patients with risk factors for aspirin resistance (AR) including diabetes, obesity, and elderly, which are also risk factors for THA/TKA and VTE. In cardiovascular disease, AR has been linked to poorer patient outcomes with a AR incidence rate of 28%; but research is lacking post-THA/TKA.
Aims: To investigate the incidence of AR in patients post-THA/TKA who are diabetic, obese and/or elderly.
Methods: A prospective cohort study of obese (body mass index (BMI) ³30 kg/m2), diabetic and/or elderly (³65 years) patients prescribed aspirin for VTE prophylaxis post-THA/TKA in a major Australian tertiary hospital. Blood samples were collected after ³7 days of aspirin therapy to conduct a platelet function analyser (PFA-100) and full blood count. Adherence was confirmed verbally and through tablet count. Patients with thrombocytopenia, taking an anticoagulant, or non-adherence were excluded. Ethics approval was granted by Metro South HREC and patients provided informed consent. Funding was provided by a Metro South Research Support Scheme grant.
Results: Thirty-four patients were included, 19 (55.9%) THA and 15 (44.1%) TKA, with a mean (±SD) age of 66.5 (±10.6) years, BMI of 31.6 (±5.8) kg/m2, and 20 (58.8%) were male. Six-weeks of aspirin 150mg daily on discharge was the most used regimen (n=18, 52.9%) with approximately 17 doses prior to analysis. The incidence of AR (Table 1) was 52.9% (n=18), of which, 4 (22.2%) were diabetic, 11 (61.1%) obese, and 11 (61.1%) elderly participants.
Total Population (n=34, 100%) |
Population without aspirin resistance (n=16, 47.1%) |
Population with aspirin resistance (n=18, 52.9%) |
|
BMI ≥30 (kg/m2) no. (%) |
23 (100%) | 12 (%) | 11 (%) |
Age ≥65 (years) no. (%) |
21 (100%) | 10 (%) | 11 (%) |
Diabetes no. (%) |
8 (100%) | 4 (50.0) | 4 (50.0%) |
Aspirin Dose (mg/day) mean (±SD) |
147.1 (±31.9) | 150.0 (±43.3) | 144.4 (±15.7) |
Number of aspirin doses taken no. (%) |
16.0 (±7.5) | 15.4 (±6.2) | 16.6 (±8.5) |
Platelet count (x109 L) mean (±SD) |
408.5 (±113.7) | 390.8 (±122.7) | 424.3 (±102.5) |
Haematocrit mean (±SD) |
0.37 (±0.04) | 0.37 (±0.03) | 0.38 (±0.04) |
PFA (s) (Collagen/Epinephrine) mean (±SD) |
169.1 (±60.5) | 241.7 (±41.2) | 132.8 (±26.3) |
PFA (s) (Collagen/Adenosine diphosphate) mean (±SD) |
92.7 (±31.1) | 95.4 (±31.9) | 71 (±7.0) |
Conclusions: In this small sample, over half the patients had AR. Aspirin may not be an appropriate agent for VTE prophylaxis for patients who are obese, have diabetes or are elderly. Further research is required to confirm the clinical implications of AR in this cohort.
To cite this abstract in AMA style:
van Oosterom N, Barras M, Cottrell N, Bird R. Aspirin Resistance after Total Hip or Knee Arthroplasties [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/aspirin-resistance-after-total-hip-or-knee-arthroplasties/. Accessed May 15, 2024.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/aspirin-resistance-after-total-hip-or-knee-arthroplasties/