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Journal of Postgraduate Medicine, Vol. 57, No. 4, October-December, 2011, pp. 350 Letter Low-dose aspirin and preeclampsia prevention S Wiwanitkit, V Wiwanitkit Wiwanitkit House, Bangkhae, Bangkok, Thailand The recent report on low-dose aspirin (LDA) and preeclampsia prevention was very interesting. [1] Based on the concept that preeclampsia is a member of the thrombohemostatic diseases, the role of aspirin in the management of preeclampsia has been studied by many researchers. Trivedi has concluded that ′LDA has a small effect in the prevention of preeclampsia in women considered to be at high risk for the disease.′ [1] This observation is very interesting; the main question is whether the authors are implying that LDA is useless in the prevention of preeclampsia. LDA has been widely used for preventive purposes for a long time. However, this work by Trivedi as well as another recent meta-analysis show that LDA might not be useful for the prevention of preelampsia. [1],[2] Rossi and Millin found that the administration of LDA could not reduce the incidence of preeclampsia and concluded that there was no evidence to support its use in the prevention of preeclampsia. [2] However, other meta-analyses have reported different results. [3],[4] Bujold et al. reported that LDA was effective in reducing the incidence of preeclampsia. They reported that LDA could help prevent 50% of preeclampsia cases and that this clinical benefit was greater when LDA administration was started early. [4] Thus, the usefulness of LDA in preventing preeclampsia is still a controversial issue. Concerns regarding the period for which LDA needs to be administered should also be kept in mind. This factor has not been fully investigated in the report by Trivedi. Another question is whether there is any other unrecognized factor that could explain such variations in the observations by different researchers. Indeed, the defect of using aspirin as a prophylaxis agent for vascular disease is of concern in thrombohemostaseology. An important factor that could explain the ineffectiveness of aspirin in some cases is aspirin resistance, a condition which can be overcome by increasing the dose of aspirin. This problem is due to individual physiological variations in the ability to metabolize aspirin. Generally, the effect of aspirin is via inhibition of platelet aggregation. Aspirin irreversibly inactivates platelet cyclooxygenase-1 in platelets, resulting in reduction of platelet aggregation. In cases of aspirin resistance the expected reduction in platelet aggregation does not take place and therefore the patient is not protected against thrombotic complications. This can be clinically or subclinically (laboratory) expressed and is a common problem in medicine. In the general population, the prevalence of aspirin resistance is about 25%, which is quite high. Thus, concern regarding this problem is required. [5] Although there are no studies on the prevalence of aspirin resistance in pregnant subjects, the prevalence is not likely to be very different from that in the general population. Screening for this condition has been suggested. Several new tools, including point-of-care analyzers, are available to help identify aspirin resistance.With prescreening for aspirin resistance, adjustment of the dosage of aspirin can be made. This might be the key to success in the use of LDA for prevention of preeclampsia in the pregnant. [5] References
Copyright 2011 - Journal of Postgraduate Medicine |
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