Psychiatric status among stepchildren and domestic and international adoptees in Denmark. A comparative nationwide register-based study

Abstract

Aims: To investigate adoptees’ psychiatric contact compared with non-adoptees and to clarify the related diagnoses. Method: Observational, nationwide, register-based study, where correlations between psychiatric, demographic and socioeconomic variables were analyzed for adoptees compared with non-adoptees. The study period is 1992—2008. The setting is Denmark, encompassing seven different types of adoptees registered from 1988 to 2005 (n = 13,524). The non-adoptees (n = 839,989) are matched on sex, age and residence. Various comparison models are designed: one with delayed entries (17 years) shows a 5.0% psychiatric contact prevalence for non-adoptees and 9.2% for adoptees (adjusted odds ratio: 2.91). Another design without delayed entries (2 years) shows a 2% prevalence for non-adoptees and 3.9% for adoptees (adjusted odds ratio 2.65). p-values <0.0005. Results: Only one type of adoptee: ‘‘registered partner’s adoption of the other partner’s child’’ has a lower risk than non-adoptees (odds ratio: 0.26). Comparison within the same birth region shows a significant increased risk for most adoption types. More adoptees than non-adoptees have more than one contact. Age at adoption is an additional risk factor for4one year only. The most frequent diagnosis is ‘‘Inherent or acquired brain suffering’’ (ICD-10: F50 — F99). Conclusions: The results stress that ‘‘adoptee’’ is an independent risk factor for psychiatric contact for international as well as for Danish adoptees. Danish stepchildren have a higher risk than non-adopted Danish children, while ‘‘registered partner’s child adopted by the other partner’’ have a lower risk than non-adopted Danish children.