The WORKWELL programme: a randomized controlled trial of job retention vocational rehabilitation for people with inflammatory arthritis.

Dysmenorrhoea (period pain) is the most common gynaecological condition in women of reproductive age (). It is characterised by cyclical menstrual pain, which may be accompanied by headaches, nausea, vomiting, diarrhoea, bloating or fatigue (). Prevalence rates for dysmenorrhoea range from 16 to 91% () or from 2 to 36% for severe pain (). It has a substantial impact on school or university attendance, social activities and quality of life () as well as significant economic consequences (). However, despite its high prevalence and personal and societal impacts, dysmenorrhoea is generally understudied, and the aetiology is not yet fully understood. Risk factors for dysmenorrhoea include smoking, longer bleeding duration, heavy menstrual flow and high stress levels (, ). Family history (FHx) has also been recognised as an important risk factor (, , ). This is usually defined as having a first-degree relative (mother, sister) with dysmenorrhoea and can increase the risk of dysmenorrhoea 3.5-fold compared to individuals with no FHx (). Women with FHx of dysmenorrhoea also tend to experience more severe pain (). This could be due to shared environments and learned behaviours regarding pain (), but a genetic component is also likely, considering twin studies have previously estimated heritability to be 38% for menstrual pain (). It is important to acknowledge that primary dysmenorrhoea (PDM) (no underlying pelvic pathology; comprising 90% of cases) () is likely to have distinct risk factors and pathogenesis to secondary dysmenorrhoea (SDM) (pain associated with an underlying disease, for example, endometriosis, adenomyosis, fibroids or pelvic inflammatory disease) (). While a laparoscopy is the only definitive method for confirming the diagnosis of PDM (by excluding SDM causes not visible on imaging), many studies report a PDM diagnosis on the basis of clinical judgement, e.g. using one or a combination of history taking, clinical examination or ultrasonography, potentially skewing the research focused on PDM.