Evaluation of an internet-based disease trajectory decision tool for prostate cancer screening.

Objective: To evaluate the application of a chronic disease model (CDM) for prostate cancer to visual analog scale (VAS) and time trade-off (TTO) decision tools.

Methods: A total of 138 men (mean age 58 years) viewed a CDM module for prostate cancer with and without prostate specific antigen (PSA) screening. Participants rated their hypothetical quality of life with potential prostate cancer treatment complications using a CDM-based VAS decision tool. They were then asked to estimate how many years they would be willing to trade to be free of treatment complications using a CDM-based TTO decision tool. The consistency between VAS and TTO scores and the relationship between scores and preferences for PSA screening test and hypothetical treatment choice for prostate cancer were then evaluated.

Results: There was a significant relationship between the VAS and TTO ratings (regression P < 0.001). The TTO tool was sensitive to age. Mean scores with standard deviations for those less than 58 years compared to those 58 years and more were 7.78 (1.75) and 8.41 (1.52), respectively (P = 0.04). Using the VAS tool, men who chose PSA screening had higher quality of life ratings compared to men who did not choose PSA screening: 7.73 (1.78) and 6.59 (2.39), respectively (P = 0.01). Similar results were found with the TTO decision tool: 8.33 (1.45) and 7.04 (2.00), respectively (P = 0.005). Men who would hypothetically prefer treatment for moderately differentiated prostate cancer also had higher TTO scores compared to men who preferred watchful waiting: 8.54 (1.39) and 7.85 (1.73), respectively (P = 0.04).

Conclusion: CDM-based for prostate cancer, VAS and TTO ratings were consistent and were concordant with patient preferences for screening; TTO ratings were also concordant with treatment choice. The use of the CDM-based TTO ratings to adjust for quality of life in decision analytic modeling needs to be explored.