Abstract
Importance: Suicide attempts are common in individuals with eating disorders. More precise understanding of the mechanisms underlying their co-occurrence is needed.
Objective: To examine the association between eating disorders and suicide attempts and whether familial risk factors contribute to the association.
Design: A cohort design following a Swedish birth cohort 1979-2001 from age 6 until 31/12/2009.
Setting: Information was acquired from Swedish national registers.
Participants: Individuals born 1979-2001 and living in Sweden before age 6 (N= 2,268,786) were eligible for the study. Each individual was linked to his/her biological full-siblings, maternal half-siblings, paternal half-siblings, full-cousins, and half-cousins.
Eating disorders were captured by three variables: any eating disorder, anorexia nervosa (AN), and bulimia nervosa (BN), identified by any lifetime diagnoses recorded in the registers.
Suicide attempts were defined as any suicide attempts, including death by suicide, recorded in the registers. We examined the association between eating disorders and death by suicide separately, but were underpowered to explore familial liability for this association.
Results: Individuals with any eating disorder had increased risk of suicide attempts (OR=5.28, 95%CI [5.04, 5.54]) and death by suicide (OR=5.39, 95%CI [4.00, 7.25]). The risks attenuated but remained significant after adjusting for comorbid major depressive disorder, anxiety disorders, and substance use disorder. Similar results were found for AN and BN, except that adjusted OR of death by suicide in BN became insignificant, possibly due to insufficient power. Individuals (index) who had a full-sibling with any eating disorder had increased risk of suicide attempts (OR=1.41, 95%CI [1.29, 1.53]). The risk attenuated for any eating disorder in more distant relatives (maternal half-siblings, OR=1.10, 95%CI [0.90, 1.34]; paternal half-siblings, OR=1.21, 95%CI [0.98, 1.49]; full-cousins, OR=1.11, 95%CI [1.06, 1.18]; half-cousins, OR=0.90, 95%CI [0.78, 1.03]). This familial pattern remained stable after adjusting for the index individuals’ eating disorders. Similar patterns were found for AN and BN.
Conclusions and Relevance: Our results suggest increased risk of suicide attempts in individuals with lifetime eating disorders and their relatives. The pattern of familial co-aggregation suggests familial liability for the association between eating disorders and suicide. Psychiatric comorbidities partially explain this association, suggesting particularly high-risk presentations.
