Preference-Based Measures (PBMs)
Preference-based measures (PBMs), or generic preference-based measures, are tools increasingly used in health economic evaluations to calculate quality-adjusted life years (QALYs). These measures typically consist of several domains (or a descriptive set) that allows patients to describe various aspects of their health, such as limitations in daily activities, mobility, pain, and discomfort.
Key features of PBMs include:
– Domains and Descriptive Sets: These measures include multiple domains that capture different aspects of a patient’s health status, which patients use to generate profile scores.
– Conversion to Index Scores: Patient-reported values (profile scores) are converted to index scores using selected algorithms. These algorithms are often country-specific and are based on general public surveys about preferences for different health state combinations, hence the term “preference-based.”
– Index Scores (Utilities): The index scores, also called ‘utilities,’ usually range from 0 to 1, where 1 represents “perfect health” and 0 represents “death.” Some measures allow for values below zero, indicating health states perceived to be worse than death.
Examples of PBMs include:
– EQ-5D: Comprises five dimensions (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) and is NICE’s preferred instrument for cost-utility evaluations in healthcare technology assessments.
– SF-6D: Derived from the SF-36 and SF-12 health surveys, it covers six dimensions of health.
– Health Utilities Index (HUI): Includes multiple dimensions such as vision, hearing, speech, ambulation, dexterity, emotion, cognition, and pain.
PBMs are crucial for health economic evaluations as they provide a standardized way to quantify health outcomes in terms of QALYs, allowing for the comparison of different healthcare interventions’ cost-effectiveness. By reflecting the general public’s preferences, these measures ensure that the valuations of health states are aligned with societal values, thus supporting informed decision-making in healthcare policy and practice.
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