Twists and turns: Sex and gender differences in the illness trajectories of common somatic symptoms

This thesis explored sex and gender differences (i.e., biological and psychosocial differences between women and men, respectively) in illness trajectories of common somatic symptoms. Common somatic symptoms are the type of symptoms that everyone experiences every once in a while, such as headache, tiredness and back pain. These symptoms usually spontaneously appear and disappear, but may persist sometimes. We’ve identified many differences between women and men in their illness trajectories. First, we assess sex and gender differences in the etiology of somatic symptoms, showing differences between women and men in the genetic contribution and the childhood socialization processes that affect one’s proneness to develop somatic symptoms. Second, we identify a female preponderance in the prevalence, severity and persistence of common somatic symptoms, including persistent symptoms surrounding COVID-19 diagnoses (i.e., long COVID). Thereafter, we show that women more frequently seek help in primary care than men for their symptoms, however GPs less frequently provide female patients with physical examinations, diagnostic imaging, or referrals to a specialist than male patients. This contributes to the lower likelihood of women receiving a disease diagnosis for their symptoms compared to men. Even when women are provided with diagnostic interventions, these are less effective in establishing disease in women than in men. We discovered a similar mechanism at play during the early COVID-19 pandemic: female healthcare providers were less frequently tested for and diagnosed with COVID-19 than their male counterparts. We not only identify differences between women and men in health and healthcare, but also provide recommendations on how to inclusively assess sex and gender in large-scale cohort studies.