Using a Modified Delphi Approach to Gain Consensus on Relevant Comparators in a Cost-Effectiveness Model: Application...

Challenges can exist when framing the decision question in a cost-effectiveness analysis, particularly when there is disagreement among experts on relevant comparators. Using prostate cancer screening and recent developments in risk stratification, early-detection biomarkers, and diagnostic technologies as a case study, we report a modified Delphi approach to handle decision-question uncertainty.

The study involved two rounds of anonymous online questionnaires to identify the prostate cancer screening strategies that international researchers, clinicians and decision makers felt important to consider in a cost-effectiveness model. Both purposive and snowball sampling were used to recruit experts. The questionnaire was based on a review of the literature and was piloted for language, comprehension and ease of use prior to dissemination. In Round 1, respondents indicated their preferred screening strategy (including no screening) through a series of multiple-choice questions. The responses informed a set of 13 consensus statements, which respondents ranked their agreement with on a 9-point Likert scale (Round 2). Consensus was considered reached if > 70% of participants indicated agreement and < 15% indicated disagreement.

Twenty participants completed Round 1 and 17 completed Round 2. Consensus was shown towards comparing no formal screening, age-based, and risk-based strategies. The risk-based approaches included screening only higher-risk men, using shorter screening intervals for higher-risk men, screening higher-risk men at an earlier age, and tailoring screening intervals based on prostate-specific antigen (PSA) level at a previous test. There was agreement that inclusion of MRI in the pathway should be considered, but disagreement on the inclusion of new biomarkers.

In disease areas where technologies are rapidly evolving, a modified Delphi approach provides a useful tool to identify relevant comparators in an economic evaluation.