Table 1

 Basic input variables and sources used in the decision models (shown in figs 1 and 2).

Input for the cost effectiveness modelsData source
AZG means empirical data from the University Hospital Groningen, UMCN means empirical data from the University Medical Centre Nijmegen.
Probability that a CRC patient:
    Satisfies selection criteriaDutch Cancer Registration
    Has a positive MSI test result (given selection criteria)AZG
    Has a DNA mutation (given MSI positive and given selection criteria)AZG
    Satisfies AC (given selection criteria and given MSI test negative)AZG
    Has a DNA mutation (given the selection criteria and given a negative MSI test and  given AC criteria)AZG, Literature20–28
    Has a positive family historyLiterature11
    That the family history is taken by medical specialistUMCN
    Satisfies AC (given a positive family history)UMCN
    Has a DNA mutation (given a positive family history and given AC)UMCN
    Has a positive MSI test result (given a positive family history and not satisfying AC)UMCN
    Has a DNA mutation (given a positive family history and not satisfying AC and  given a positive MSI test result)UMCN, AZG, Literature20–28
Probabilities that a first degree family member of a CRC patient:
    Satisfies the AC or has a CRC family member with positive DNA test result according  to the new strategyPatient model
    Satisfies the AC or has a CRC family member with positive DNA test result according  to the current strategyPatient model
    Is tested because the CRC family member has a positive DNA test resultPatient model
    Satisfies the AC without a verified detected mutation in the CRC family member, has  an MLH1 or MSH2 mutationLiterature21,36,40
    Has an MLH1 or MSH2 mutation (given the mutation in the CRC patient)Literature11
    Has an MLH1 or MSH2 mutation (not satisfying the AC and without a detected  mutation in the CRC family member)Expert opinion
Probability that:
    A negative DNA test result is a true negative resultLiterature21,36,40; expert opinion
    A negative MSI test result is a true negative resultMeta-analysis29
    Not satisfying AC is true negativeLiterature29
Costs
    MSI, DNA, counselling by a clinical geneticist, colonoscopy, subtotal colectomyUMCN
    Follow up of an HNPCC patientPatient records