Abstract
Sex and gender-related factors are strongly associated with patients' illness trajectories, underscoring their essential role in epidemiological research and healthcare. Ignoring sex and gender in research and health inevitably results in inequities between women and men in terms of detection of disease, preventative measures, and effectiveness of treatment. Historical influences, including ideas of female inferiority and conservative notions of women's health only comprising reproductive health, reinforced the perceived irrelevance of sex and gender to health. Currently, these ideas are largely abandoned and epidemiology is becoming increasingly sensitive to sex. Gender-sensitivity, however, is lagging behind. This is potentially due to lacking knowledge and awareness about the relevance of both sex and gender to health and challenges in operationalizing gender in epidemiological research. Here, we thoroughly discuss the relevance of sex and gender to health, and pay special attention to the time, place, and culture-dependent embodiment of gender. We also discuss the operationalization of gender via composite gender scores in epidemiological studies. We argue to move beyond solely using these. Rather we should consider sex and gender in the initial stages of designing a study, to facilitate relevant, reproducible, and person-centric research.