Familial, psychiatric, and socioeconomic risk factors for suicide in young people: nested case-control study

Objective To estimate the risk of suicide in young people related to family and individual psychiatric and socioeconomic factors. Design Population based nested case-control study. Setting Data from longitudinal Danish registers. Cases and controls 496 young people aged 10-21 years who had committed suicide during 1981-97 in Denmark and 24 800 controls thatched for sex, age, and time. Main outcome measures All suicides in Denmark compared with controls; parents and siblings identified from population based registers; inpatient information from discharge registers of national hospitals; and socioeconomic data from administrative registers. Results Parental factors associated with an increased risk of suicide in young people were suicide or early death, admission to hospital for a mental illness, unemployment, low income, poor schooling, and divorce, as well as mental illness in siblings and mental illness and short duration of schooling in the young people themselves. The strongest risk factor was mental illness in the young people. The effect of the parents' socioeconomic factors decreased after adjustment for a family history of mental illness and a family history of suicide. Conclusions Recognising mental illness in young people and dealing with it appropriately could help prevent suicides. The high relative risk associated with a low socioeconomic status of the parents may be confounded and overestimated if not adjusted for mental illness and suicide in the family.