Why Elicit Preferences Before Defining Dose Utility?
A dose-finding objective can include efficacy, toxicity, and the burden of receiving treatment, but choosing those outcomes does not by itself specify how they should be valued. A patient may consider a modest efficacy gain worthwhile only if the chance of a serious adverse event remains low. A clinician may focus on preventing that event, while another stakeholder may emphasize symptom relief or time spent receiving treatment. Structured elicitation makes these judgments explicit before they are encoded in a dose utility.
The aim is not to ask stakeholders to calculate a utility function. It is to collect clear, interpretable evidence about what matters, which tradeoffs are acceptable, and where opinions differ. The questions should describe treatment consequences in a consistent clinical context, and the responses should be recorded with enough detail to distinguish a firm preference from an uncertain or conditional one.
Earlier material on constructing joint benefit-risk utility functions establishes why a dose decision may need to account for more than one outcome. Here the emphasis is on how to ask stakeholders about those outcomes. The resulting evidence can inform which attributes to include, how to describe them, and which tradeoffs deserve further evaluation. It should not be presented as though a small set of answers establishes a single preference shared by all patients.
Designing Questions That Stakeholders Can Answer
Start with the decision the utility will support. Specify the disease, treatment setting, relevant patient population, comparator, and time horizon. For example, a question about the chance of nausea during the first treatment cycle is not interchangeable with a question about persistent nausea over a year. Similarly, “more effective” is too vague unless the respondent knows what outcome improves, by how much, and over what period.
Then define the attributes that will appear in the scenarios. Efficacy might be expressed as the chance of symptom improvement by a stated time; toxicity might be the chance of a named adverse event with a clear severity and duration; treatment burden might include infusion time, visit frequency, or daily dosing. Use units and absolute risks where possible. Keep the wording understandable, and do not imply that a modeled outcome is certain or guaranteed.
A useful sequence moves from comprehension to comparison. First ask the respondent to explain, in their own words, what each outcome means. Next ask which outcomes matter most in the stated decision. Then use carefully varied scenarios to explore tradeoffs. Finally, ask how certain the respondent is and what information, assumption, or personal circumstance influenced the answer. Open-ended follow-up questions are valuable because a choice alone rarely explains its rationale.
Avoid leading language. “Would you accept a dangerous treatment for a chance of benefit?” steers the respondent through emotionally loaded wording. A more neutral version describes the outcomes concretely and asks which option they would choose, or whether they regard either as preferable. Avoid combining several changes in one comparison: if efficacy, toxicity, and visit burden all change at once, the reason for a preference is hard to identify.
Useful Elicitation Formats
- Direct attribute questions. Ask which outcomes are important, what makes an outcome unacceptable, and what treatment burden is manageable. These questions help identify relevant attributes and concerns, but answers such as “toxicity matters most” do not specify how much toxicity a person would trade for a particular benefit.
- Controlled pairwise comparisons. Present two profiles that differ in one attribute, or in a clearly defined tradeoff between two attributes. Ask which is preferred, whether they seem equally desirable, and how confident the respondent is. Pairwise questions are often easier to understand than asking for numerical weights.
- Threshold or boundary probes. Hold the benefit description fixed and vary a harm, or hold the harm fixed and vary a benefit. Ask at which point the respondent would switch preference, or whether there is a range where neither option is clearly favored. This reveals a boundary or interval, not necessarily a precise point.
- Acceptability questions. Ask whether a profile would be acceptable, unacceptable, or acceptable only under specified conditions. Follow up on the conditions. Acceptability is a useful clinical judgment, but it is not automatically a hard safety constraint or a complete ordering of all possible options.
- Open-ended explanation. Ask what drove the response and whether it depends on personal circumstances, such as disease severity, prior experience, or caregiving responsibilities. These explanations can expose missing attributes and important sources of variation.
Ranking several profiles can provide a quick view of broad priorities, but a rank order alone says little about the size or stability of differences in preference. It should be treated as one form of preference evidence rather than as a complete account of tradeoffs. Converting ranks into numerical utility weights is a separate task.
Worked Example: Separating Efficacy, Toxicity, and Burden
Suppose a hypothetical elicitation team is preparing questions for adults considering a treatment for a chronic condition. It proposes two profiles for a 12-week treatment period:
- Option A: 60 of 100 similar patients are expected to achieve a meaningful symptom improvement; 5 of 100 are expected to experience a specified severe adverse event; treatment requires one 30-minute clinic visit each week.
- Option B: 68 of 100 are expected to achieve the same improvement; 10 of 100 are expected to experience the same severe adverse event; treatment requires one 30-minute clinic visit each week.
The question is: “Assuming these estimates apply over the same 12-week period, which option would you prefer, or do you regard them as about equally desirable? How certain are you, and what matters most in your choice?” The common time horizon, identical event definition, and equal visit burden make the central comparison clearer: Option B offers an 8-percentage-point higher improvement rate and a 5-percentage-point higher severe-event rate.
A respondent chooses Option A and explains that avoiding the severe event matters more than the additional chance of symptom improvement. This supports a specific interpretation: for this respondent and these stated profiles, the extra improvement in Option B does not outweigh its additional severe-event risk. It does not establish that the respondent rejects all increases in risk, nor does it quantify a general exchange rate between benefit and harm.
Before using this response, the team should check that the respondent understood “severe adverse event” and noticed that visit burden was identical. If the respondent thought Option B involved more visits, the answer would not isolate the intended tradeoff. The team should also ask whether the choice changes for a patient with more severe symptoms, since the value of the stated improvement may depend on baseline circumstances.
Locating a Preference Boundary
When a respondent’s preference changes as one attribute varies, a sequence of questions can locate a boundary more clearly than a single comparison. For example, keep the expected symptom-improvement rate fixed and vary the severe-event risk. The respondent can indicate which profile they prefer at each level. A boundary is the level or range where the respondent switches from favoring one profile to favoring the other, or reports that neither is clearly preferred.
This approach relies on an important assumption: over the range tested, the respondent’s preference changes in an orderly direction as the varying attribute changes. If increasing harm risk while holding everything else fixed makes an option more desirable for some responses, the answers may reflect misunderstanding, random response, a changed interpretation, or a genuine non-monotone preference that requires investigation. Do not force a single threshold if the data do not support one.
Worked Example: Bracketing an Acceptable Risk Level
A hypothetical respondent compares two 12-week profiles. Both offer a 70% chance of meaningful improvement and require the same treatment schedule. The only difference is the chance of a specified severe adverse event. In each comparison, Option A has a 4% event risk; Option B has the higher risk shown below. The respondent is asked which option they prefer, or whether they are about equally desirable.
The respondent prefers Option B when its event risk is 6%, but prefers Option A when Option B’s risk is 14%. Thus, assuming preference is monotone over this range, the changeover lies between 6% and 14%. The team next asks about 10%. The respondent prefers Option A, so the bracket narrows to between 6% and 10%. At 8%, the respondent reports that the options are about equally desirable. This sequence suggests a boundary near 8% for these particular profiles and this respondent.
The arithmetic underlying the final bracket is simply the comparison of tested risk levels: the initial interval has width \(14\%-6\%=8\) percentage points. Testing its midpoint, \((6\%+14\%)/2=10\%\), gives a new interval of width \(10\%-6\%=4\) percentage points. Testing the midpoint of that interval, \((6\%+10\%)/2=8\%\), produces the respondent’s reported indifference. These calculations locate the tested boundary; they do not establish that the underlying preference is exactly 8%, especially if responses are uncertain or inconsistent.
The team should record the result as a boundary for the specified profiles, not as a universal “acceptable risk.” It should ask how confident the respondent is, whether the event’s severity or duration changes the judgment, and whether the answer would differ for a different improvement rate. If the respondent gives contradictory answers at successive risk levels, the team should pause and clarify the scenarios rather than continue narrowing a misleading interval.
Comparing Stakeholder Groups and Checking Response Quality
Patients, clinicians, caregivers, and policy stakeholders may answer from different roles and experiences. Elicit and summarize these perspectives separately before considering how they should inform a decision. A clinician’s judgment about the consequences of toxicity is not the same as a patient’s experience of that toxicity. Likewise, a group average can conceal a minority for whom a treatment burden is especially important.
Use a common core of questions when comparing groups, while allowing appropriate follow-up questions for each group. Record who responded, the context of the interview, which profiles were shown, and the wording and order of questions. If respondents see multiple comparisons, order can influence later answers: a severe scenario presented first may make subsequent risks seem less concerning. Pilot the questions with people similar to the intended respondents and revise confusing terms before the main elicitation.
Worked Example: Interpreting Differences Between Stakeholder Groups
In a hypothetical pilot, 20 patients and 10 clinicians each compare the same two profiles. The profiles have identical treatment burden and a 10-percentage-point difference in symptom improvement. One profile also has a 5-percentage-point higher risk of a specified severe adverse event. Suppose 13 of 20 patients prefer the profile with the lower event risk, compared with 4 of 10 clinicians.
The descriptive proportions are \(13/20=0.65\), or 65% of the patient respondents, and \(4/10=0.40\), or 40% of the clinician respondents. In this pilot, a larger share of patient respondents favored the lower-risk profile. The difference is \(65\%-40\%=25\) percentage points. These summaries describe the respondents who answered these questions; they do not show that stakeholder group caused the preference or establish population-wide proportions.
The team should inspect the explanations and confidence ratings before interpreting the contrast. Patients may have understood the adverse event differently, or the clinician respondents may have considered a clinical context not specified in the profile. The small, hypothetical pilot is useful for identifying questions to investigate, not for declaring that patients generally value risk more than clinicians. A follow-up might clarify event consequences and ask both groups why they made their choices.
Useful diagnostics include frequent requests for clarification, inconsistent choices across near-identical scenarios, missing responses, extreme answers that appear to reflect a misunderstanding, and large changes when wording or order changes. Examine these signals by respondent as well as by stakeholder group. A response can be valid but uncertain; it should not be discarded simply because it differs from the majority. Instead, retain uncertainty and explain how it affects interpretation.
From Elicited Judgments to a Defensible Utility Specification
Preference evidence helps the analysis team make transparent modeling decisions. It can identify which efficacy, toxicity, and burden outcomes should be represented; highlight outcomes that require clinically meaningful categories; and show where a single summary may obscure important differences. It can also reveal that stakeholders disagree about the decision itself, not merely about a numerical input.
Elicitation does not replace clinical evidence. Respondents describe how they value stated consequences; trial and model data describe how likely those consequences are at each dose. Keep the two kinds of evidence distinct. Likewise, an elicited statement that a particular profile is unacceptable should prompt careful examination, but the team must state separately whether it is being used as a preference, a decision rule, or a formal safety constraint.
For traceability, document the stakeholder groups, recruitment context, question wording, attribute definitions, time horizon, scenario values, response options, follow-up explanations, and any revisions made after piloting. Report uncertainty and disagreement rather than hiding them behind a single consensus label. A defensible utility specification makes clear which preference evidence informed its structure and where judgments remain unresolved.
| Approach | What it is useful for | Main limitation |
|---|---|---|
| Open-ended questions | Finding relevant outcomes and reasons for preferences | Responses can be difficult to compare across people |
| Pairwise comparisons | Exploring choices between clearly described profiles | A choice alone may not reveal its rationale or certainty |
| Threshold probes | Identifying a boundary or range under stated conditions | Depends on comprehension and orderly responses across scenarios |
| Ranking profiles | Describing a broad ordering of options | Does not by itself describe the strength of preference |
Common Pitfalls
- Wrong reasoning: “Most respondents ranked efficacy first, so efficacy should receive the largest numerical utility weight.”
Correction: A ranking indicates ordering, not the magnitude of tradeoffs. Ask targeted comparisons and retain the distinction between stated priority and a calibrated utility weight. - Wrong reasoning: “The respondent accepted a 10% event risk, so 10% is safe for every patient.”
Correction: The answer applies to the respondent and profile described. A preference judgment is not a population safety conclusion or a universal clinical limit. - Wrong reasoning: “The two groups disagree, so one group must have misunderstood.”
Correction: Check comprehension, but also allow that preferences, experiences, and decision roles genuinely differ. Report the difference and its uncertainty rather than forcing agreement. - Wrong reasoning: “A profile with more efficacy and more toxicity tells us which outcome drove the choice.”
Correction: Unless the comparison isolates the attributes or includes follow-up, the response reflects the combined profile and cannot identify the reason on its own. - Wrong reasoning: “A single boundary is precise because the respondent chose one side at each question.”
Correction: Choices can be uncertain, context-dependent, or inconsistent. Report the tested range and confidence, and do not claim greater precision than the responses justify.
Check Your Understanding
Answer each question, then compare your reasoning with the solutions below.
- Why should the time horizon and event definition be stated consistently when comparing treatment profiles?
- A respondent prefers a profile with greater efficacy and greater toxicity. What can you conclude, and what remains unknown?
- In a threshold probe, a respondent favors a low-risk profile at 12% event risk but a higher-benefit profile at 6% risk. Under what assumption can the preference boundary be bracketed between these values?
- In a pilot, 9 of 15 patient respondents favor one profile and 6 of 12 clinicians favor it. Calculate both proportions and explain one limitation of the comparison.
- Why is an “acceptable” profile not automatically a hard safety constraint?
Solutions. (1) Consistent framing makes the compared consequences refer to the same period and outcome, so a response is less likely to reflect changed definitions or horizons. (2) The respondent prefers the combined profile as presented; without isolating attributes or asking follow-up questions, we do not know which outcome drove the choice or the size of any tradeoff. (3) Assume preference changes monotonically as event risk changes while the other profile features remain fixed. Then the switch lies between 6% and 12%, although uncertainty may make the boundary imprecise. (4) The proportions are \(9/15=0.60\), or 60%, and \(6/12=0.50\), or 50%. They describe these respondents only; the groups may differ in sample composition, and the small pilot does not establish population preferences. (5) Acceptability is a respondent’s judgment about a stated profile. Treating it as a binding safety rule is a separate decision that requires explicit justification and clinical governance.