Evaluation of the Biological Response to Acetylsalicylic Acid by Platelet Occlusion Time in Pregnant Women in Brazzaville

Low-dose acetylsalicylic acid (ASA) has been recommended for pregnant women since 2011 by the OMS to prevent thrombotic phenomena. Despite the variability of its clinical efficacy (resistance phenomena), its non-standardized biological monitoring can be performed using platelet occlusion time (POT). The aim of this study was to assess the response to ASA using POT.

A multicenter, cross-sectional, analytical study was conducted in the obstetrics and gynaecology departments of six Brazzaville hospitals over a period of 09 months and included pregnant women on ASA 100 mg daily for at least 7 days. POT was measured using the INNOVANCE® PFA®-200 system. The variables studied were clinical (age, medical and obstetrical history) and biological (blood count, POT). Non-response to ASA was defined by a POT of 150 seconds or less. Data analysis was performed using STATA 12 software. Logistic regression was used to assess the determinants associated with non-response. The incidence of obstetric complications according to ASA resistance was evaluated by the Kaplan-Meier method and the Log-Rank test. The significance threshold was p<0.005.

The study involved 39 pregnant women, mean age 33.9 ± 5.4 years, treated with ASA for hypertensive disorders of pregnancy n=19 (48.7%), chronic arterial hypertension n=7 (18%), diabetes n=3(7.7%) fetal death n=3(7.7%), unexplained miscarriage n=3(7.7%), advanced age n=2 (5.1%) and twin pregnancy n=2(5.1%). The median body index was 25.5 kg/m2 [23.7;29.4] with 35.9% women of normal weight, 48.7% overweight and 15.4% obese. Non-response to ASA was found in 12 pregnant women (30.7%). No statistically significant differences were observed between non-responders and responders with regard to epidemiological, clinical and haematological determinants (p>0.05). Non-response was more observed in women with complications 23.08% versus 7.7% (p=0,008).

Non-response to ASA, present in a third of hypertensive pregnant women, is associated with the occurrence of obstetrical complications in Brazzaville.