Page 56 - Screening for Cervical Cancer: Systematic Evidence Review

Chapter III. Results

• Substantial uncertainty surrounds the estimates of sensitivity and specificity of thin-

layer cytology and computerized rescreening technologies compared with each other

and with conventional Pap testing. This uncertainty is not reflected in the point

estimates of cost-effectiveness. Although both thin-layer cytology and computerized

rescreening technologies clearly improve effectiveness at higher cost, the imprecision

in estimates of effectiveness makes drawing conclusions about the relative cost-

effectiveness of thin-layer cytology and computerized rescreening technologies

problematic.

• Given the uncertainty surrounding these estimates, all three technologies may well

fall within accepted ranges of cost-effectiveness at 3-year screening intervals. No

strategy or technology used for screening more often than every 3 years results in

estimates of less than $50,000 per life-year.

This model substantially improves on prior work; it includes global costs of downstream

care resulting from screening and cancers, more accurate estimates of the performance of

conventional cytology then previously available, and sophisticated sensitivity analyses.

However, important parameters of this model deserve note. Base assumptions include the

following: (1) all women receive screening at the appropriate interval; (2) new technologies

increase sensitivity without any decrement in specificity; (3) all patients receive appropriate

follow-up; and (4) diagnostic evaluation of abnormal cytology detects all true abnormalities (i.e.,

no colposcopy or pathology errors are made). Adjusting each of these assumptions closer to

actual clinical scenarios has the effect of increasing the cost-effectiveness ratio. If, as our update

and the full Cervical Cytology report suggest, new technologies do have lower specificity than

56