Issues in COVID-19 research and statistical analyses (Part XVVXV)
July 15, 2022 In a recent article in Science Advances , Lee et al discuss the changes in menstrual bleeding after Sars-CoV-2 vaccination that women in different groups of oral contraceptive use, hormones, or post-menopausal for a large part reported breakthrough bleeding. Initially in the pandemic, the media and even doctors were dismissive of these women’s claims that vaccination had any effect on menstrual bleeding. However, researchers started like the authors started taking an interest in this research. The patients were recruited through a survey propagated through many vehicles of social media so though they used many avenues to recruit people, there may be response bias and certainly confounding. The methods they used were multivariate logistic regression for the main analysis of heavy menstrual bleeding. Afterward they did restrict the sample size down to persons who had two doses of vaccine or one dose of Johnson & Johnson amongst some other restrictions. Thus in this article they did a retrospective observational study of vaccinated women instead of doing a prospective study with 35,572 women. In terms of their results from this sample, they found that 42% of people with regular menstrual cycles bled more heavily than usual, while 44% reported no change after being vaccinated. Among those survey respondents who typically do not menstruate, 71% of people on long-acting