Psychiatric disorders and mortality due to external causes following diagnosis of endometriosis at a young age: a longitudinal register-based cohort study in Finland

Abstract

BackgroundEndometriosis diagnosed in adults is associated with increased risk of various psychiatric disorders. However, little is known concerning psychiatric comorbidity and mortality due to external causes associated with endometriosis diagnosed at a young age. Objective(s)In this longitudinal cohort study, we investigated the link between surgical diagnosis of endometriosis at a young age, and subsequent psychiatric disorders and mortality due to external causes. Additionally, we compared the occurrence of the most common psychiatric disorders between different sites of surgically confirmed endometriosis (ovarian versus other) due to possible different pain manifestations. Study DesignWe conducted a retrospective register-based cohort study. Altogether 4532 women with surgically confirmed diagnosis of endometriosis before the age of 25 in 1987–2012 were identified from the Finnish Hospital Discharge Register and matched with women without surgically diagnosed endometriosis for age and municipality on the index day (n=9014). Women were followed from the index day until the end of 2019 for the outcomes of interest, which included nine groups of psychiatric disorders (inpatient episodes since 1987, outpatient episodes since 1998) and death due to external causes, including deaths due to accidents, suicides, and violence (Finnish Register of Causes of Death). Cox proportional hazard models were applied to assess the crude and parity-adjusted hazard ratios and 95% confidence intervals. ResultsThe cohort’s median age was 22.9 years (interquartile range: 21.3–24.1) at the beginning and 42.5 years (36.7–48.3) after a median follow-up time of 20.0 years (14.5–25.7). We observed a higher hazard of depressive, anxiety, and bipolar disorders in women with endometriosis compared to the reference cohort. These differences appeared early and remained the same during the entire follow-up, irrespective of whether assessed from the data on inpatient episodes only, or using data on both in- and outpatient episodes. The corresponding adjusted hazard ratios were 2.57 (95% confidence interval 2.11–3.14) and 1.87 (1.65–2.12) for depressive disorders, 2.40 (1.81–3.17) and 2.09 (1.84–2.37) for anxiety disorders, 1.71 (1.30–2.26) and 1.66 (1.28–2.15) for bipolar disorders, respectively. A higher hazard was seen for nonorganic sleeping disorders for the first ten years only (3.83, 2.01–7.30) when assessed using the data on both in- and outpatient episodes. When based on inpatient records, a higher hazard for alcohol/drug dependence after 15 years of follow-up (2.07, 1.21–3.54) was observed. The difference in hazard for personality disorders tended to increase during follow-up (<10 years 2.12, 1.28–3.52; 10 years or more 3.08, 1.44–6.57). Depressive and anxiety disorders occurred more frequently in women with other than ovarian endometriosis. No difference in deaths due to external causes was observed between the endometriosis and reference cohorts. Conclusion(s)Surgical diagnosis of endometriosis at young age associated with increased incidence for several psychiatric disorders. Moreover, within the endometriosis population, psychiatric comorbidity was more common in women with other than ovarian endometriosis. We speculate that chronic pain is essential in the development of these psychiatric disorders, and that early and effective pain management is important in reducing the risk of psychiatric morbidity in young women. More research concerning the associations and management of endometriosis and associated psychiatric disorders is warranted.