Table 4

One way sensitivity analyses

VariableInterpretationBaseline valueRange of valuesThreshold value7-150
A7-151 B7-152
pSens Sensitivity of genetic strategy forAPC mutation in proband0.740.00–1.000.100.31
p15 Proportion of relatives between ages 10 and 20 years0.600.00–1.00 7-153 0.37
p25 Proportion of relatives between ages 20 and 30 years0.200.00–1.00 7-153 7-153
p35 Proportion of relatives between ages 30 and 40 years0.200.00–1.00 7-153 7-153
pCarry Risk of carryingAPCmutation0.500.00–1.000.840.55
pExp Degree of expression ofAPCmutation0.900.00–1.00 7-153 0.71
p20 Detection of FAP polyps between ages 15 and 25 years0.900.00–1.00 7-153 0.20
p30 Detection of FAP polyps between ages 25 and 35 years0.990.00–1.00 7-153 7-153
p40 Detection of FAP polyps between ages 35 and 50 years1.000.00–1.00 7-153 7-153
N Number of relatives in a family61–10 7-153 2.18
cProb Cost for genetic testing forAPC mutation in proband420100–2500 7-153 1154
cRel Cost for genetic testing of each relative252100–2500851396
• 7-150 The threshold19 value is a value where the two screening strategies have equal expected costs. If a given variable has a value less than the threshold value, then one strategy is cheaper; if the variable has a value greater than the threshold, then the alternative strategy is cheaper.

• 7-151 Assuming the same frequency of clinical screening for both strategies (FAP model A).

• 7-152 Assuming anual screening for relatives testing positive for theAPC mutation under genetic route (FAP model B).

• 7-153 The genetic strategy is less expensive than the clinical one over all the given range of values (no threshold).