Data selection and analysis
Articles were screened on reporting an association between endometriosis and depressive or anxiety symptoms. Furthermore, factors correlated with or contributing to this association were listed. Data from studies using validated outcome measures and reporting a mean and standard deviation (SD) concerning depression or anxiety scores in endometriosis patients compared with a control group, were pooled. The corresponding author was contacted if a mean and/or SD was not provided in the article, and additional data were added to pooling. Values were not included when not following a normal distribution. A random effects meta-analysis was carried out using STATA version 14 Software. Because of the heterogeneity in assessment tools, a standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated. The heterogeneity was tested through I-squared tests with a significance level of 5%. Mean age (and SD) of cases and controls are provided in order to assess comparability.
Results
Selection process The database search initially identified 1,837 records. After removal of duplicates and adding articles from reference lists, 1,289 remained for screening on title and abstract. 127 articles were assessed on full text. Consensus was obtained in 90%, the remaining 10% were handled by discussion and a third opinion. Finally, 47 articles were included and a systematic qualitative review was performed [27-73]. Due to variations in study design, lack of control groups, different methods of measuring outcome and due to missing data, only 17 articles were eligible for data-pooling and meta-analysis [28,29,35,38,43,46,38,51,54-56,57,60-62,67,68]. Figure 1 shows a flowchart of the literature review process.