Dear Editor,


We read with interest the systematic review and meta-analysis of RCTs by Yip et al. [1] which aims to investigate the role of different dosages and initial time of aspirin initiation in preeclampsia prevention. We congratulate the authors for choosing the topic. The use of aspirin prevents the onset of preeclampsia [2] and determining the dosage and time to start its use is important to bring security to professionals. Nevertheless, some points about the study need to be clarified. We did not find the publication of the review protocol record throughout the study and/or other sources. Was it registered on PROSPERO or another platform? We believe that some important databases were missing to carry out the searches, such as SCOPUS, LILACS, SciELO and CINAHL. Despite not limiting the period, the search extended until May 2020, while the study was published in January 2022, so we imagine that the interval of one and a half years is long enough for the existence of publications that may not have been found and analyzed. The lack of this information, which could alter the results achieved, tends to modify the effect estimates and the conclusions of the study. Therefore, based on the above mentioned, there is a characterization of publication bias [3]. Moreover, another identified gap concerns the fact that the authors did not use the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system to assess the quality of the evidence [4, 5]. The lack of this evaluation makes it difficult for health professional for prescribing the correct dose and time of aspirin in the prevention of preeclampsia, because with the absence of GRADE, we do not know the quality of the current evidence on the topic and whether the estimated effect found may change or not with future studies.