title: Computer simulation to estimate the effectiveness of carotid endarterectomy.
abstract: OBJECTIVE
  To investigate the benefit of carotid endarterectomy relative to medical treatment, by comparing the outcome for different groups of patients following transient ischaemic attacks.
  
  
  METHODS
  A Markov model was used to describe the survival and quality of life of patients treated for a transient ischaemic attack. The benefit is measured in terms of quality adjusted life months (QALMs). The outcome was estimated using a computer simulation with parameters based on published studies on the probability of events following treatment. The benefit of carotid endarterectomy was explored using a baseline set of parameters and a sensitivity analysis.
  
  
  RESULTS
  The baseline scenario of a 65-year-old male patient with the model factors set at an intermediate level showed a benefit for surgery of 3 QALMs compared with medical treatment alone. The sensitivity analysis showed that the most favourable combination of factors had a benefit of 13.4 QALMs and the least favourable a loss of 2 QALMs. Of all 128 factor combinations, 79.9% showed a benefit for surgery, 5.5% showed equal benefit, and 15.6% showed a benefit for medical treatment.
  
  
  CONCLUSIONS
  Computer simulations have the potential for deriving estimates of benefit for different patient groups from the results of clinical trials. Combined with reliable information on costs, the technique could also demonstrate variations in cost-effectiveness for these groups. For patients following a transient ischaemic attack, the results from this simulation and limited cost information suggest that carotid endarterectomy is unlikely to be a cost-effective intervention in the UK for many patient groups despite a reduction in the risk of stroke.
authors.affiliation: Newcastle and North Tyneside Health Authority, UK.
authors.forename: M
authors.initials: M
authors.lastname: Lavender
authors.forename: N
authors.initials: N
authors.lastname: Craig
authors.forename: R
authors.initials: R
authors.lastname: Kerr
authors.forename: D
authors.initials: D
authors.lastname: Howel
mesh_terms: D000368:Aged; D003198:Computer Simulation; D003362:Cost-Benefit Analysis; D016894:Endarterectomy, Carotid / Q000191:economics / Q000592:standards / Q000706:statistics & numerical data*; D017048:Health Care Costs; D006801:Humans; D002546:Ischemic Attack, Transient / Q000601:surgery*; D008297:Male; D008390:Markov Chains; D017059:Models, Econometric; D019057:Quality-Adjusted Life Years; D016019:Survival Analysis; D013673:Technology Assessment, Biomedical / Q000379:methods*; D016896:Treatment Outcome; D006113:United Kingdom