title: Predictors of suicidal ideation in older people: a decision tree analysis.
abstract: OBJECTIVE
  Suicide among older adults is a major public health issue worldwide. Although studies have identified psychological, physical, and social contributors to suicidal thoughts in older adults, few have explored the specific interactions between these factors. This article used a novel statistical approach to explore predictors of suicidal ideation in a community-based sample of older adults.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Participants aged 55-85 years were randomly selected from the Hunter Region, a large regional center in New South Wales, Australia.
  
  
  METHODS
  Baseline psychological, physical, and social factors, including psychological distress, physical functioning, and social support, were used to predict suicidal ideation at the 5-year follow-up. Classification and regression tree modeling was used to determine specific risk profiles for participants depending on their individual well-being in each of these key areas.
  
  
  RESULTS
  Psychological distress was the strongest predictor, with 25% of people with high distress reporting suicidal ideation. Within high psychological distress, lower physical functioning significantly increased the likelihood of suicidal ideation, with high distress and low functioning being associated with ideation in 50% of cases. A substantial subgroup reported suicidal ideation in the absence of psychological distress; dissatisfaction with social support was the most important predictor among this group. The performance of the model was high (area under the curve: 0.81).
  
  
  CONCLUSIONS
  Decision tree modeling enabled individualized "risk" profiles for suicidal ideation to be determined. Although psychological factors are important for predicting suicidal ideation, both physical and social factors significantly improved the predictive ability of the model. Assessing these factors may enhance identification of older people at risk of suicidal ideation.
authors.affiliation: Centre for Translational Neuroscience and Mental Health, University of Newcastle, Callaghan, Australia. Electronic address: tonelle.handley@newcastle.edu.au.
authors.forename: Tonelle E
authors.initials: TE
authors.lastname: Handley
authors.affiliation: Centre for Translational Neuroscience and Mental Health, University of Newcastle, Callaghan, Australia.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Hiles
authors.affiliation: Centre for Translational Neuroscience and Mental Health, University of Newcastle, Callaghan, Australia; Hunter Medical Research Institute, Hunter Region Mail Centre, Newcastle, Australia.
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Inder
authors.affiliation: Centre for Translational Neuroscience and Mental Health, University of Newcastle, Callaghan, Australia; National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia.
authors.forename: Frances J
authors.initials: FJ
authors.lastname: Kay-Lambkin
authors.affiliation: Centre for Translational Neuroscience and Mental Health, University of Newcastle, Callaghan, Australia; Hunter Medical Research Institute, Hunter Region Mail Centre, Newcastle, Australia.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Kelly
authors.affiliation: Centre for Translational Neuroscience and Mental Health, University of Newcastle, Callaghan, Australia; Hunter Medical Research Institute, Hunter Region Mail Centre, Newcastle, Australia.
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Lewin
authors.affiliation: Centre for Clinical Epidemiology and Biostatistics, University of Newcastle, Newcastle, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: McEvoy
authors.affiliation: Centre for Clinical Epidemiology and Biostatistics, University of Newcastle, Newcastle, Australia.
authors.forename: Roseanne
authors.initials: R
authors.lastname: Peel
authors.affiliation: Hunter Medical Research Institute, Hunter Region Mail Centre, Newcastle, Australia; Centre for Clinical Epidemiology and Biostatistics, University of Newcastle, Newcastle, Australia.
authors.forename: John R
authors.initials: JR
authors.lastname: Attia
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease / Q000523:psychology; D003663:Decision Trees; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012944:Social Support; D013315:Stress, Psychological / Q000150:complications / Q000523:psychology; D059020:Suicidal Ideation
keywords: CART; decision tree; older; physical functioning; psychological distress; social support; suicidal ideation