Cost comparison of predictive genetic testing versus conventional clinical screening for familial adenomatous polyposis

B Bapat,^ab H Noorani,^a Z Cohen,^a T Berk,^a A Mitri,^b B Gallie,^d K Pritzker,^b S Gallinger,^a A S Detsky^c

^a Familial GI Cancer Registry, Mount Sinai Hospital, University of Toronto, Toronto, Canada, ^b Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Canada, ^c Department of Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Canada, ^d Molecular and Medical Genetics, Department of Ophthalmology and Division of Immunology and Cancer Research, The Hospital for Sick Children and Eye Research Institute of Canada, University of Toronto, Toronto, Canada

Correspondence to: Dr B Bapat, Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.

Accepted for publication 4 November 1998

BACKGROUNDMutations of the APC gene cause familial adenomatous polyposis (FAP), a hereditary colorectal cancer predisposition syndrome.
AIMSTo conduct a cost comparison analysis of predictive genetic testing versus conventional clinical screening for individuals at risk of inheriting FAP, using the perspective of a third party payer.
METHODSAll direct health care costs for both screening strategies were measured according to time and motion, and the expected costs evaluated using a decision analysis model.
RESULTSThe baseline analysis predicted that screening a prototype FAP family would cost $4975/£3109 by molecular testing and $8031/£5019 by clinical screening strategy, when family members were monitored with the same frequency of clinical surveillance (every two to three years). Sensitivity analyses revealed that the genetic testing approach is cost saving for key variables including the kindred size, the age of screening onset, and the cost of mutation identification in a proband. However, if the APC mutation carriers were monitored at an increased (annual) frequency, the cost of the genetic screening strategy increased to $7483/£4677 and was especially sensitive to variability in age of onset of screening, family size, and cost of genetic testing of at risk relatives.
CONCLUSIONSIn FAP kindreds, a predictive genetic testing strategy costs less than conventional clinical screening, provided that the frequency of surveillance is identical using either strategy. An additional significant benefit is the elimination of unnecessary colonic examinations for those family members found to be non-carriers.
(Gut 1999;44:698-703)

Keywords: familial adenomatous polyposis;  adenomatous polyposis coli gene;  cost analysis;  genetic testing