Study subjects
A total of 1,933,846 subjects were reviewed, including 154,725 endometriosis patients, 1,778,317 healthy controls, 418 CPP patients without endometriosis and 386 infertile women without endometriosis. For the comparison of patient groups, different types of methods were used. Twenty-one studies investigated anxiety and depression symptoms in endometriosis patients without including a control group [27,33,34,36,37,39-42,45,47,49,50,52,58,59,63,65,66,69,70,72,73]. Twenty-six studies compared endometriosis patients with a group of either healthy controls [30,32,35,38,39,46,51,55], CPP patients without endometriosis [29,48,54,60,67], infertile patients without endometriosis [61,64] or a combination of control groups [28,43,44,53,56,57,62,68,71]. Four studies compared endometriosis patients with pain symptoms to pain-free endometriosis patients [28,34,35,47]. Two studies compared endometriosis patients with and without infertility [59,62].