Table 5.

Incremental cost-effectiveness ratios—base case and sensitivity analyses.

	Base case * ($)	Scenario 1 † ($)	Scenario 2 ‡ ($)	Scenario 3 § ($)
Cost of extending LDA by 1 week	141 (105–193)	183	156	115
Cost of an additional negative urine	70 (53–117)	92	78	51

LDA = longest duration abstinent during study.

^*Base case corresponds to actual implementation of the original trial. 95% confidence intervals in parentheses.

^†Unfavorable scenario assumes (1) $4.80 test cups (the unit cost of test cups averaged $11.57 in the trial), (2) usual care group gets tested half as often (0.75 times per week) but retains 100% of their patient outcomes, (3) full-scale implementation has no effect on the unit cost of administering the prize system and (4) full overhead rate is applied to labor costs.

^‡Realistic scenario assumes (1) $4.80 test cups, (2) usual care group gets tested half as often (0.75 times per week) but retains 100% of their patient outcomes, (3) full-scale implementation reduces the unit cost of administering the prize system by 50% and (4) one-half (50%) of the overhead rate is applied to labor costs.

^§Favorable scenario assumes (1) $4.80 test cups, (2) usual care group gets tested once per week and retains 85% of their patient outcomes, (3) full-scale implementation reduces the unit cost of administering the prize system by 75% and (4) one-quarter (25%) of the overhead rate is applied to labor costs.