title: Towards renewed health economic simulation of type 2 diabetes: risk equations for first and second cardiovascular events from Swedish register data.
abstract: OBJECTIVE
  Predicting the risk of future events is an essential part of health economic simulation models. In pursuit of this goal, the current study aims to predict the risk of developing first and second acute myocardial infarction, heart failure, non-acute ischaemic heart disease, and stroke after diagnosis in patients with type 2 diabetes, using data from the Swedish National Diabetes Register.
  
  
  METHODS
  Register data on 29,034 patients with type 2 diabetes were analysed over five years of follow up (baseline 2003). To develop and validate the risk equations, the sample was randomly divided into training (75%) and test (25%) subsamples. The Weibull proportional hazard model was used to estimate the coefficients of the risk equations, and these were validated in both the training and the test samples.
  
  
  RESULTS
  In total, 4,547 first and 2,418 second events were observed during the five years of follow up. Experiencing a first event substantially elevated the risk of subsequent events. There were heterogeneities in the effects of covariates within as well as between events; for example, while for females the hazard ratio of having a first acute myocardial infarction was 0.79 (0.70-0.90), the hazard ratio of a second was 1.21 (0.98-1.48). The hazards of second events decreased as the time since first events elapsed. The equations showed adequate calibration and discrimination (C statistics range: 0.70-0.84 in test samples).
  
  
  CONCLUSIONS
  The accuracy of health economic simulation models of type 2 diabetes can be improved by ensuring that they account for the heterogeneous effects of covariates on the risk of first and second cardiovascular events. Thus it is important to extend such models by including risk equations for second cardiovascular events.
authors.affiliation: Division of Health Economics, Department of Clinical Sciences, Malmö University Hospital, Lund University, Malmö, Sweden. aliasghar.ahmad_kiadaliri@med.lu.se
authors.forename: Aliasghar
authors.initials: A
authors.lastname: Ahmad Kiadaliri
authors.forename: Ulf-G
authors.initials: UG
authors.lastname: Gerdtham
authors.forename: Peter
authors.initials: P
authors.lastname: Nilsson
authors.forename: Björn
authors.initials: B
authors.lastname: Eliasson
authors.forename: Soffia
authors.initials: S
authors.lastname: Gudbjörnsdottir
authors.forename: Katarina Steen
authors.initials: KS
authors.lastname: Carlsson
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000191:economics* / Q000209:etiology; D003198:Computer Simulation; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000191:economics*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000191:economics / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018803:Models, Economic; D009203:Myocardial Infarction / Q000191:economics / Q000209:etiology; D017202:Myocardial Ischemia / Q000191:economics / Q000209:etiology; D016016:Proportional Hazards Models; D012042:Registries / Q000706:statistics & numerical data; D018570:Risk Assessment / Q000379:methods / Q000706:statistics & numerical data*; D012307:Risk Factors; D020521:Stroke / Q000191:economics / Q000209:etiology; D013548:Sweden