title: Psychosocial Assessment of Self-Harm Patients and Risk of Repeat Presentation: An Instrumental Variable Analysis Using Time of Hospital Presentation.
abstract: BACKGROUND
  Clinical guidelines have recommended psychosocial assessment of self-harm patients for years, yet estimates of its impact on the risk of repeat self-harm vary. Assessing the association of psychosocial assessment with risk of repeat self-harm is challenging due to the effects of confounding by indication.
  
  
  METHODS
  We analysed data from a cohort study of 15,113 patients presenting to the emergency departments of three UK hospitals to investigate the association of psychosocial assessment with risk of repeat hospital presentation for self-harm. Time of day of hospital presentation was used as an instrument for psychosocial assessment, attempting to control for confounding by indication.
  
  
  RESULTS
  Conventional regression analysis suggested psychosocial assessment was not associated with risk of repeat self-harm within 12 months (Risk Difference (RD) 0.00 95% confidence interval (95%CI) -0.01 to 0.02). In contrast, IV analysis suggested risk of repeat self-harm was reduced by 18% (RD -0.18, 95%CI -0.32 to -0.03) in those patients receiving a psychosocial assessment. However, the instrument of time of day did not remove all potential effects of confounding by indication, suggesting the IV effect estimate may be biased.
  
  
  CONCLUSIONS
  We found that psychosocial assessments reduce risk of repeat self-harm. This is in-line with other non-randomised studies based on populations in which allocation to assessment was less subject to confounding by indication. However, as our instrument did not fully balance important confounders across time of day, the IV effect estimate should be interpreted with caution.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Carroll
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Metcalfe
authors.affiliation: Centre for Suicide Prevention, University of Manchester, Manchester, United Kingdom.
authors.forename: Sarah
authors.initials: S
authors.lastname: Steeg
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.|Medical Research Council Integrative Epidemiology Unit, University of Bristol, Bristol, United Kingdom.
authors.forename: Neil M
authors.initials: NM
authors.lastname: Davies
authors.affiliation: Centre for Suicide Prevention, University of Manchester, Manchester, United Kingdom.
authors.forename: Jayne
authors.initials: J
authors.lastname: Cooper
authors.affiliation: Centre for Suicide Prevention, University of Manchester, Manchester, United Kingdom.|Manchester Mental Health and Social Care Trust, Manchester, United Kingdom.
authors.forename: Nav
authors.initials: N
authors.lastname: Kapur
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.|The National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care West (NIHR CLAHRC West) at University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Gunnell
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D012044:Regression Analysis; D012306:Risk; D016728:Self-Injurious Behavior / Q000523:psychology* / Q000628:therapy; D013997:Time Factors