Why can’t we just offer aspirin to all women? Why do we need to implement a screening test?
If aspirin is effective and ‘safe’ it should be given to those that would benefit from it the most. As Prof. Zarco Alfirevic commented on the NEJM website “a word of caution to all enthusiasts out there who will now start to advocate (near) universal prescribing of low dose aspirin in pregnancy. The FMF algorithm has identified an interesting phenotype which appears to respond to aspirin very well. We cannot and should not assume that all screen negative women will respond equally well to aspirin. Furthermore, current safety data are reassuring but still limited.“
The ASPRE screening algorithm, for the same screen positive rate as per NICE (The National Institute for Health and Care Excellence), identifies 75% of cases of pre-term pre-eclampsia.
It identifies a group of at risk women that responds to aspirin in the prevention of pre-term pre-eclampsia.
In addition, we should consider the issue of compliance. A study (McNulty et al, 2011) found that compliance with Folic acid supplementation was only 19% and led to the recommendation of fortification of food in many countries.
Though aspirin is considered safe in drug trials, nonetheless, it is a drug with known side effects, and therefore high risk women for pre-term pre-eclampsia should be identified and compliance with aspirin prophylaxis should be ensured throughout pregnancy.
This is an indication of the level of compliance that can be expected in a motivated high-risk group of women, who are being actively managed by their physicians. Adherence according to trial group is presented in Table 2.
Furthermore, if universal aspirin prophylaxis is to be implemented, in a screened population of 10,000 women, you would give aspirin to 10,000 women to prevent 33 cases of pre-term pre-eclampsia. This means you would give aspirin to more than 9,000 women unnecessarily.