Survival analytic studies of suicide risk

Sammanfattning: Survival Analytic Studies of Suicide Risk Peter Nordström, M.D. Dissertation from the Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet S-171 76 Stockholm, SwedenSuicide 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 andprediction in the clinical setting is a task of paramount concern to psychiatric services.Suicide risk evaluation in individual patients requires clinical judgment and empiricalresearch data from longitudinal clinical follow-up studies of high suicide risk samples isneeded to support good clinical practice and a reasonable standard of care for suicidalpatients.A major suicide risk prediction hypothesis is that suicide occurs as the endpoint of anescalating suicidal process over time, starting with suicidal ideation and with a suicideattempt as the typical mode of clinical presentation. Mental disorder is an integral part ofthe vulnerability to suicide and certain personality traits might contribute to a suicidaltemperament, perhaps with psychobiological roots. Recently a serotonin hypothesis ofsuicide risk has been launched which has received considerable empirical support.The diagnosis of attempted suicide and suicide is established through the evaluation andclinical 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 observationwere 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 shifttowards 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 riskassessment and prediction issues as well as the psychobiological hypotheses of serotoninand temperament as possible suicide risk predictors.From the clinical studies it was concluded that the suicide risk is 6% within a few yearsafter attempted suicide and 10% among the younger suicidal men. A current suicideattempt predicts a 12 % one-year suicide risk among depressed psychiatric inpatients.Among depressed suicide attempters, low CSF 5-HIAA predicts a lower number ofsurvived patient months and a suicide risk of 17% within one year. Features of suicidaltemperament may include trait anxiety, hopelessness, hostility and low socialization.Anxiety proneness, impulsivity and low socialization are implicated as possible aspects ofa temperamental vulnerability to suicide risk and correlate with survival time in earlysuicides 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 basisfor future suicide prevention and treatment research targeting suicide risk.Key Words: Suicide risk, suicide, attempted suicide, mood disorder, serotonin,CSF 5-HIAA, personality, temperament, birth cohort analysis, survival analysisStockholm 1995 ISBN 91-628-1805-8