Survival analytic studies of suicide risk

Abstract

Suicide is a major cause of death in Sweden, as measured by potential years of life lost, and suicidal behavior is a grave public health problem. Suicide risk assessment and prediction in the clinical setting is a task of paramount concern to psychiatric services. Suicide risk evaluation in individual patients requires clinical judgment and empirical research data from longitudinal clinical follow-up studies of high suicide risk samples is needed to support good clinical practice and a reasonable standard of care for suicidal patients. A major suicide risk prediction hypothesis is that suicide occurs as the endpoint of an escalating suicidal process over time, starting with suicidal ideation and with a suicide attempt as the typical mode of clinical presentation. Mental disorder is an integral part of the vulnerability to suicide and certain personality traits might contribute to a suicidal temperament, perhaps with psychobiological roots. Recently a serotonin hypothesis of suicide risk has been launched which has received considerable empirical support.

The diagnosis of attempted suicide and suicide is established through the evaluation and clinical judgment of circumstantial evidence and reflects acts of purposely inflicted self-harm with some intent to die, resulting in injury, poisoning, or suffocation. Suicide risk is the probability of suicide within a certain time span of observation. Survival analysis and the conditional probabilities of surviving each period of observation were used to calculate cumulative survival and suicide risk over time. Median split subgrouping by relevant factors was used to study the effect on suicide risk. Birth cohort analysis of suicide in Sweden 1952-1981 showed a suicide risk age shift towards younger age with increased suicide risk particularly among young men.

Five clinical high suicide risk studies, which included nearly 2000 individuals altogether, had a specific focus on attempted suicide and addressed clinically relevant suicide risk assessment and prediction issues as well as the psychobiological hypotheses of serotonin and temperament as possible suicide risk predictors. From the clinical studies it was concluded that the suicide risk is 6% within a few years after attempted suicide and 10% among the younger suicidal men. A current suicide attempt predicts a 12 % one-year suicide risk among depressed psychiatric inpatients. Among depressed suicide attempters, low CSF 5-HIAA predicts a lower number of survived patient months and a suicide risk of 17% within one year. Features of suicidal temperament may include trait anxiety, hopelessness, hostility and low socialization. Anxiety proneness, impulsivity and low socialization are implicated as possible aspects of a temperamental vulnerability to suicide risk and correlate with survival time in early suicides after attempted suicide. Support was lended to the male suicide risk age shift, the suicidal process, the temperamental vulnerability and the serotonin hypotheses of suicide risk. It is hoped that the findings presented in this thesis will contribute to the empirical basis for future suicide prevention and treatment research targeting suicide risk.