Introduction
Endometriosis is defined as an estrogen-dependent condition with presence of endometrium-like tissue outside the uterus [1]. The prevalence has been estimated between 2% to 10% in women of reproductive age and up to 50% in women with chronic pelvic pain (CPP) or fertility problems [2,3]. A combination of retrograde menstruation, defective immune clearance and changes in the peritoneal environment that stimulate cell growth is the most widely accepted explanation with regard to etiopathogenic mechanisms [4]. Dysmenorrhea, CPP, dyspareunia, fatigue/weariness and infertility are the leading symptoms [5,6,7], and the non-specific presentation of these symptoms often causes a delay concerning diagnosis [8-10]. Severity of the disease, pelvic pain, infertility, and a higher number of years since diagnosis are associated with higher costs of societal relevance, as symptoms affect physical, mental, sexual, and social well-being, as well as work productivity [11-13]. Furthermore, the extent of endometriosis is not directly related to the degree of symptoms [14] and recurrence of symptoms after surgical or medical interventions occurs frequently [15]. Hence, the perception of symptoms may be associated with psychological distress, such as in depression and anxiety disorders [16,17]. Depression and anxiety disorders are classified by the DSM-V psychiatric diagnostic criteria [18], and the global prevalence of depressive and anxiety disorders ranges from 4.5-7% and 5.5-6% respectively in women of reproductive age [19]. A relationship between depression, anxiety and endometriosis has been described from 1979 onward [20]. Demographic characteristics, social and disease-specific factors may predict psychological ill-health in endometriosis patients and could therefore lead to potential prediction models for the risk of developing depression or anxiety disorders in these patients.
The aim of this systematic review is to give an overview of what is known about the association between endometriosis and symptoms of depression or anxiety regarding its strength and direction, and to further examine which factors are associated. In addition, this review may help to elucidate the importance of psychiatric screening and to evaluate which patients are vulnerable for developing depression or anxiety disorders. This is important for clinical practice since the presence of anxiety and depression may influence the perception of symptoms, the prognosis, compliance with treatment and quality of life [21].
Methods
This systematic review was registered in PROSPERO (CRD42018106983) and was conducted following the PRISMA guidelines [22,23].