title: The impact of under and over-recording of cancer on death certificates in a competing risks analysis: a simulation study.
abstract: BACKGROUND
  With linked register and cause of death data becoming more accessible than ever, competing risks methodology is being increasingly used as a way of obtaining "real world" probabilities of death broken down by specific causes. It is important, in terms of the validity of these studies, to have accurate cause of death information. However, it is well documented that cause of death information taken from death certificates is often lacking in accuracy and completeness.
  
  
  METHODS
  We assess through use of a simulation study the effect of under and over-recording of cancer on death certificates in a competing risks analysis consisting of three competing causes of death: cancer, heart disease and other causes. Using realistic levels of misclassification, we consider 24 scenarios and examine the bias in the cause-specific hazard ratios and the cumulative incidence function.
  
  
  RESULTS
  The bias in the cumulative incidence function was highest in the oldest age group reaching values as high as 2.6 percentage units for the "good" cancer prognosis scenario and 9.7 percentage units for the "poor" prognosis scenario.
  
  
  CONCLUSIONS
  The bias resulting from the chosen levels of misclassification in this study accentuate concerns that unreliable cause of death information may be providing misleading results. The results of this simulation study convey an important message to applied epidemiological researchers.
authors.affiliation: Centre for Biostatistics and Genetic Epidemiology, Department of Health Sciences, 2nd Floor Adrian Building, University Road, University of Leicester, Leicester LE1 7RH, UK. srh20@leicester.ac.uk
authors.forename: Sally R
authors.initials: SR
authors.lastname: Hinchliffe
authors.forename: Keith R
authors.initials: KR
authors.lastname: Abrams
authors.forename: Paul C
authors.initials: PC
authors.lastname: Lambert
mesh_terms: D002423:Cause of Death; D003644:Death Certificates; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology*; D016016:Proportional Hazards Models; D018570:Risk Assessment; D011795:Surveys and Questionnaires