Is testing for aspirin response worthwhile in high-risk pregnancy?

OBJECTIVE

To explore the clinical impact of aspirin dosage adjustment in pregnant women at high risk of hypertensive disorders.

STUDY DESIGN

In this retrospective observational study including women with pre-existing hypertension, pre-gestational diabetes or previous placental-mediated complications, we compared the rates of pre-eclampsia, early-onset and severe pre-eclampsia between women who used 81 mg of aspirin (ASA) throughout pregnancy without platelet function analyser (PFA-100®) monitoring ("group ASA no PFA") and those in whom the aspirin dosage was adjusted according to PFA-100® results ("group ASA and PFA").

RESULTS

270 women were included in the analyses, 111 in group ASA and PFA and 159 in group ASA no PFA. Aspirin was started before 13 weeks in 71.7% of women in group ASA no PFA and in 79.3% of those in group ASA and PFA. PFA-100® monitoring was associated with a lower rate of pre-eclampsia (15.3% vs. 30.8%; aOR 0.36, 95%CI 0.19-0.67) and severe pre-eclampsia (3.6% vs. 15.1%; aOR 0.22, 95% CI 0.07-0.66), after adjustment for various risk factors for pre-eclampsia. The rate of early-onset pre-eclampsia was not statistically different between the two groups (7.2% vs. 13.2%; aOR 0.42, 95%CI 0.17-1.04). The rate of pre-eclampsia was higher in women who needed an increase in aspirin dosage (11/43, 25.6%) than in those who did not (6/68, 8.8%, p=0.03).

CONCLUSION

Our results suggest that a strategy involving platelet function testing and individualized dosing is effective in preventing pre-eclampsia in high risk women. PFA testing should not be considered as standard practice, however, until prospective controlled randomized trials have confirmed these observations.