Aspirin for Evidence-Based Preeclampsia Prevention trial: effect of aspirin on length of stay in the neonatal intensive care unit.

BACKGROUND: Preeclampsia is a major pregnancy complication with adverse short- and long-term implications for both the mother and baby. Screening for preeclampsia at 11-13 weeks' gestation by a combination of maternal demographic characteristics and medical history with measurements of biomarkers can identify about 75% of women who develop preterm preeclampsia with delivery at <37 weeks' gestation and 90% of those with early preeclampsia at <32 weeks, at a screen-positive rate of 10%. A recent trial (Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Preeclampsia Prevention) has reported that in women identified by first-trimester screening as being at high risk for preeclampsia, use of aspirin (150 mg/d from the first to the third trimester), compared to placebo, reduced the incidence of preterm preeclampsia, which was the primary outcome, by 62% (95% confidence interval, 26-80%) and the incidence of early preeclampsia by 89% (95% confidence interval, 53-97%). The surprising finding of the trial was that despite the reduction in preeclampsia the incidence of admission to the neonatal intensive care unit, which was one of the secondary outcomes, was not significantly affected (odds ratio, 0.93; 95% confidence interval, 0.62-1.40). OBJECTIVE: We sought to examine the effect of prophylactic use of aspirin during pregnancy in women at high risk of preeclampsia on length of stay in the neonatal intensive care unit. STUDY DESIGN: This was a secondary analysis of data from the Aspirin for Evidence-Based Preeclampsia Prevention trial to assess evidence of differences in the effect of aspirin on length of stay in neonatal intensive care. Bootstrapping was used for the comparison of mean length of stay between the aspirin and placebo groups. Logistic regression was used to assess treatment effects on stay in the neonatal intensive care unit. RESULTS: In the trial there were 1620 participants and 1571 neonates were liveborn. The total length of stay in neonatal intensive care was substantially longer in the placebo than aspirin group (1696 vs 531 days). This is a reflection of significantly shorter mean lengths of stay in babies admitted to the neonatal intensive care unit from the aspirin than the placebo group (11.1 vs 31.4 days), a reduction of 20.3 days (95% confidence interval, 7.0-38.6; P = .008). Neonatal intensive care of babies born at <32 weeks' gestation contributed 1856 (83.3%) of the total of 2227 days in intensive care across both treatment arms. These occurred in 9 (1.2%) of the 777 livebirths in the aspirin group and in 23 (2.9%) of 794 in the placebo group (odds ratio, 0.42; 95% confidence interval, 0.19-0.93; P = .033). Overall, in the whole population, including 0 lengths of stay for those not admitted to the neonatal intensive care unit, the mean length of stay was longer in the placebo than aspirin group (2.06 vs 0.66 days; reduction of 1.4 days; 95% confidence interval, 0.45-2.81; P = .014). This corresponds to a reduction in length of stay of 68% (95% confidence interval, 20-86%). CONCLUSION: In pregnancies at high risk of preeclampsia administration of aspirin reduces the length of stay in the neonatal intensive care unit by about 70%. This reduction could essentially be attributed to a decrease in the rate of births at <32 weeks' gestation, mainly because of prevention of early preeclampsia. The findings have implications for both short- and long-term health care costs as well as infant survival and handicap.

Aspirin for Evidence-Based Preeclampsia Prevention trial: effect of aspirin in prevention of preterm preeclampsia in subgroups of women according to their characteristics and medical and obstetrical history.

BACKGROUND: The Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Preeclampsia Prevention trial demonstrated that in women who were at high risk for preterm preeclampsia with delivery at <37 weeks' gestation identified by screening by means of an algorithm that combines maternal factors and biomarkers at 11-13 weeks' gestation, aspirin administration from 11 to 14 until 36 weeks' gestation was associated with a significant reduction in the incidence of preterm preeclampsia (odds ratio 0.38; 95% confidence interval, 0.20 to 0.74; P=0.004). OBJECTIVE: We sought to examine whether there are differences in the effect of aspirin on the incidence of preterm preeclampsia in the Aspirin for Evidence-Based Preeclampsia Prevention trial in subgroups defined according to maternal characteristics and medical and obstetrical history. STUDY DESIGN: This was a secondary analysis of data from the Aspirin for Evidence-Based Preeclampsia Prevention trial. Subgroup analysis was performed to assess evidence of differences in the effect of aspirin on incidence of preterm preeclampsia in subgroups defined by maternal age (<30 and ≥30 years), body mass index (<25 and ≥25 kg/m2), racial origin (Afro-Caribbean, Caucasian and other), method of conception (natural and assisted), cigarette smoking (smoker and non-smoker), family history of preterm preeclampsia (present and absent), obstetrical history (nulliparous, multiparous with previous preterm preeclampsia and multiparous without previous preterm preeclampsia), history of chronic hypertension (present and absent). Interaction tests were performed on the full data set of patients in the intention to treat population and on the data set of patients who took ≥ 90% of the prescribed medication. Results are presented as forest plot with P values for the interaction effects, group sizes, event counts and estimated odds ratios. We examined whether the test of interaction was significant at the 5% level with a Bonferroni adjustment for multiple comparisons. RESULTS: There was no evidence of heterogeneity in the aspirin effect in subgroups defined according to maternal characteristics and obstetrical history. In participants with chronic hypertension preterm preeclampsia occurred in 10.2% (5/49) in the aspirin group and 8.2% (5/61) in the placebo group (adjusted odds ratio, 1.29; 95% confidence interval, 0.33-5.12). The respective values in those without chronic hypertension were 1.1% (8/749) in the aspirin group and 3.9% (30/761) in the placebo group (adjusted odds ratio, 0.27; 95% confidence interval, 0.12-0.60). In all participants with adherence of ≥90% the adjusted odds ratio in the aspirin group was 0.24 (95% confidence interval, 0.09-0.65); in the subgroup with chronic hypertension it was 2.06 (95% confidence interval, 0.40-10.71); and in those without chronic hypertension it was 0.05 (95% confidence interval, 0.01-0.41). For the complete data set the test of interaction was not significant at the 5% level (P = .055), but in those with adherence ≥90%, after adjustment for multiple comparisons, the interaction was significant at the 5% level (P = .0019). CONCLUSION: The beneficial effect of aspirin in the prevention of preterm preeclampsia may not apply in pregnancies with chronic hypertension. There was no evidence of heterogeneity in the aspirin effect in subgroups defined according to maternal characteristics and obstetrical history.