Background. We aimed to illustrate that health economists should consider individual heterogeneity when solving the
problem of finding the optimal combination of sensitivity and specificity that maximizes the average health utility of
a target population in a screening program. Methods. A theoretical framework compares the solution under standard
economics of diagnoses to the optimal combination under an endogenous uptake analysis, where screening participation
is given by heterogenous health preferences. An applied example used calibrated parameters with real data from
the bowel cancer screening program in the United Kingdom. Scenario analyses show how the results would change
with parameter values, if disease risk and health utilities were not independent and if screening uptake were not completely
determined by health preferences. Results. A general theoretical result states that the endogenous uptake analysis
leads to a weakly higher true- and false-positive rate than would be optimal under the standard approach. In the
same way, the endogenous solution would lead to a lower uptake rate. The base-case scenario of the applied example
illustrates that a screening program using the endogenous solution would generate 21.1% more quality-adjusted lifeyears
than when using the standard solution. The scenario analyses show when the endogenous analysis is most
valued and that the general result applies for a wide range of situations when theoretical assumptions are relaxed.
Limitations. The results obtained are valid under the assumptions made. Analysts should evaluate if those could hold
in the applied screening context. Conclusions. Individual heterogeneity and uptake decisions are relevant factors to
consider in the problem of finding an optimal combination of sensitivity and specificity for a screening test.
