Purpose:  Utility-elicitations are based on the assumption that patients have underlying preferences representing logically-consistent ordering of values for health states.  Individual-level joint state utility elicitations offer the opportunity to test for logical consistency.  We characterize logical and illogical utility orderings for joint states in patients at the time of prostate biopsy.

   Methods:  Subjects were men presenting for prostate biopsy (n = 223).  Utilities were elicited using time-tradeoff for the single states of impotence (IMP), urinary incontinence (UI), post-prostatectomy without complications (PP), and watchful waiting (WW); dual states combining IMP with UI, PP, and WW; and a triple state combining IMP, UI, and PP.  Responses are characterized as “illogical” if the joint state utility is higher than for component states.  T-tests of logical ordering and explanatory correlates for “illogicality” are tested. 

   Results:  For the sample average, all of the joint states are logically ordered (see table), and all differences but two are statistically significantly different. At the individual level, the percent of illogical responses for joint states were substantial (35.9 – 45.4%). Additionally, only 39.1% of respondents logically ordered all 4 joint states. No demographic characteristics were correlated with degree of logical ordering, but generalized anxiety is modestly correlated (r  = .13; p = .06). 

   Conclusions: Joint state utilities are logically ordered at the aggregate level.  However, a substantial percentage of illogical orderings occur at the individual level, and less than 40% of respondents give consistent answers across all joint states. The only correlate of illogical orderings was generalized anxiety, suggesting respondents with heightened anxiety are least likely to offer consistent values, at least in prostate cancer.

 

Utilities for Health States in Prostate Cancer
Health State	n	Mean	SEM
Single States
Post-prostatectomy	220	79.3	1.90
Watchful Waiting	223	78.6	1.89
Impotence	222	72.8	2.01
Incontinence	221	68.1	2.18
Joint States
Impotence & ...
Post-prostatectomy	221	70.4	2.12
Watchful Waiting	220	65.6	2.29
Incontinence	220	62.7	2.33
Impotence, Incontinence & Post-Prostatectomy	219	64.1	2.30