R SHANMUGALINGAM1,2,3, XS WANG6, K CHAU3,4, B XU3, G LEE1, R KUMAR, A HENNESSY1,2,3, A MAKRIS1,2,3,5
1South Western Sydney Local Health District, Liverpool, Australia, 2Western Sydney University, , Australia, 3Heart Research Institute, , Australia, 4University of Sydney, , Australia, 5University of New South Wales, , Australia, 6Bosch Mass Spectrometry Facility, Bosch Institute, Sydney Medical School, University of Sydney, SYDNEY, Australia
Aim: To examine the incidence of aspirin non-compliance and resistance and compare this against self-reported compliance. To examine clinical outcomes against biochemical compliance.
Background: Benefit of low-dose aspirin in preventing preeclampsia is well established. Despite prescription of aspirin, 30-40% of women develop preeclampsia. Aspirin-resistance and non-compliance has not been examined in high-risk pregnant women and could, in-part, explain the lack of clinical response.
Methods: Sequential recruitment of high-risk pregnant women was undertaken in metropolitan hospitals. Clinical data with a 3-point questionnaire and plasma collection was undertaken at 8 time-points (12,16,20,24,28,32,36,38 weeks gestation). Blood samples were assessed for PFA 100 (platelet function analyser) and plasma salicylate acid (SA) detection through liquid-chromatography, mass-spectrometry (LCMS). Non-compliance was defined as normal PFA100 and non-detectable plasma SA in <90% timepoints. Resistance was defined as a normal PFA100 but detectable plasma SA. Clinical outcomes were compared between compliant and non-compliant women prescribed aspirin <16 weeks of gestation. Statistical analysis utilised chi-squared analysis and linear regression(SPSSv24).
Results: Seventy-one women completed the protocol. Biochemical non-compliance was identified in 22(31%) women and only 45(63%) of women’s self-reported compliance corresponded biochemically (kappa coefficient=0.65)). No women were aspirin resistant. Clinical outcomes of women compliant and non-compliant with aspirin were significantly different. Compliant women had a lower incidence of late-onset preeclampsia (4.1% vs 59% %,p<0.001), lower blood pressure (p=0.01) and were more than 34 weeks of gestation at delivery (96% vs 81%,p=0.02). Incidence of early-onset preeclampsia (2% vs 18%, p=0.001) and IUGR was lower (4.1% vs 23% p=0.003), favouring > 90% compliance.
Conclusion: Aspirin non-compliance is more likely than aspirin resistance and self-reporting is not a reliable measure. Women who are non-compliant have worse clinical outcomes.
Dr.Shanmugalingam is a Nephrologist with an interest in obstetric medicine. She is currently undertaking her PhD in examining the role of aspirin in preventing preeclampsia