title: Validation of suicide and self-harm records in the Clinical Practice Research Datalink.
abstract: OBJECTIVE
  The UK Clinical Practice Research Datalink (CPRD) is increasingly being used to investigate suicide-related adverse drug reactions. No studies have comprehensively validated the recording of suicide and nonfatal self-harm in the CPRD. We validated general practitioners' recording of these outcomes using linked Office for National Statistics (ONS) mortality and Hospital Episode Statistics (HES) admission data.
  
  
  METHODS
  We identified cases of suicide and self-harm recorded using appropriate Read codes in the CPRD between 1998 and 2010 in patients aged ≥15 years. Suicides were defined as patients with Read codes for suicide recorded within 95 days of their death. International Classification of Diseases codes were used to identify suicides/hospital admissions for self-harm in the linked ONS and HES data sets. We compared CPRD-derived cases/incidence of suicide and self-harm with those identified from linked ONS mortality and HES data, national suicide incidence rates and published self-harm incidence data.
  
  
  RESULTS
  Only 26.1% (n = 590) of the 'true' (ONS-confirmed) suicides were identified using Read codes. Furthermore, only 55.5% of Read code-identified suicides were confirmed as suicide by the ONS data. Of the HES-identified cases of self-harm, 68.4% were identified in the CPRD using Read codes. The CPRD self-harm rates based on Read codes had similar age and sex distributions to rates observed in self-harm hospital registers, although rates were underestimated in all age groups.
  
  
  CONCLUSIONS
  The CPRD recording of suicide using Read codes is unreliable, with significant inaccuracy (over- and under-reporting). Future CPRD suicide studies should use linked ONS mortality data. The under-reporting of self-harm appears to be less marked.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK. kyla.thomas@bristol.ac.uk
authors.forename: Kyla H
authors.initials: KH
authors.lastname: Thomas
authors.forename: Neil
authors.initials: N
authors.lastname: Davies
authors.forename: Chris
authors.initials: C
authors.lastname: Metcalfe
authors.forename: Frank
authors.initials: F
authors.lastname: Windmeijer
authors.forename: Richard M
authors.initials: RM
authors.lastname: Martin
authors.forename: David
authors.initials: D
authors.lastname: Gunnell
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D059019:Clinical Coding; D016208:Databases, Factual / Q000706:statistics & numerical data*; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D005260:Female; D058005:General Practitioners; D006801:Humans; D015994:Incidence; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D016728:Self-Injurious Behavior / Q000139:chemically induced / Q000453:epidemiology*; D017678:Sex Distribution; D013405:Suicide / Q000706:statistics & numerical data*; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult