Assessing differences in utility scores: a comparison of four widely used preference-based instruments

Area of Science:

• Health Economics
• Health-Related Quality of Life (HRQoL) Measurement
• Psychometrics

Background:

• Preference-based instruments are crucial for measuring HRQoL in cost-utility analyses (CUA).
• Variations in utility scores (dUTY) among instruments like EQ-5D, HUI2, HUI3, and SF-6D can affect CUA outcomes.
• Understanding factors influencing these dUTY variations is essential for accurate economic evaluations.

Purpose of the Study:

• To compare utility scores from four preference-based HRQoL instruments.
• To assess the impact of dUTY differences on CUA.
• To identify sociodemographic and clinical factors affecting dUTY variations.

Main Methods:

• Survey of 667 adults in Singapore using EQ-5D, HUI2, HUI3, and SF-6D.
• Agreement assessed via Bland-Altman plots.
• Impact on incremental cost-utility ratio (ICUR) evaluated using decision trees.
• Sociodemographic/clinical factor influence analyzed using multiple linear regression (MLR).

Main Results:

• Median utility scores varied from 0.80 (EQ-5D) to 0.89 (SF-6D).
• Clinically important differences (CID) in dUTY exceeded 0.04 in four of six pairwise comparisons.
• ICUR differences ranged from 0.3% to 6.3% compared to base cases.
• Chronic conditions, marital status, and family functioning significantly influenced dUTY.

Conclusions:

• Despite present CIDs in utility measurements, their impact on CUA appears minor.
• Sociodemographic factors (marital status) and clinical factors (chronic conditions, family functioning) influence dUTY differences.
• These findings support careful consideration of instrument choice and patient characteristics in CUA.