Eligibility and prescribing of low-dose aspirin for preeclampsia prevention under two international guidelines: a retrospective cohort study

OBJECTIVES: The primary objective was to compare eligibility for low-dose aspirin prophylaxis according to the American College of Obstetricians and Gynecologists (ACOG) and the National Institute for Health and Care Excellence (NICE) recommendations. Secondary objectives were to evaluate aspirin prescribing among eligible women and preeclampsia outcomes according to guideline eligibility. METHODS: This retrospective cohort study included 1,064 pregnant women with complete clinical data from a tertiary referral hospital in Türkiye. Eligibility was determined according to ACOG and NICE criteria. Agreement was assessed using Cohen's kappa and McNemar's test. Aspirin prescribing and preeclampsia outcomes were also evaluated. RESULTS: According to the ACOG criteria, 311 women (29.23 %, 95 % CI, 26.58-32.03 %) were eligible for aspirin prophylaxis, whereas 130 (12.22 %, 95 % CI, 10.39-14.32 %) met the NICE criteria. The overall agreement between the two guidelines was 82.9 %, with moderate concordance (Cohen's kappa=0.50). McNemar's test demonstrated a significant difference in patient classification (p<0.001). Aspirin was prescribed to only 25.4 % of ACOG-eligible women and 48.5 % of NICE-eligible women. Overall, preeclampsia occurred in 38 of 1,064 women (3.57 %; 95 % CI, 2.61-4.86 %). Among women eligible for aspirin prophylaxis, preeclampsia developed in 23 of 311 women (7.4 %; 95 % CI, 4.98-10.85 %) according to ACOG criteria and in 16 of 130 women (12.3 %; 95 % CI, 7.72-19.06 %) according to NICE criteria. CONCLUSIONS: Although the ACOG guideline identified substantially more women as eligible for aspirin prophylaxis than the NICE guideline, documented aspirin prescribing remained considerably lower than guideline-defined eligibility, highlighting an implementation gap in routine clinical practice.