Discussion
DISORDER
This study assessed sensitivity to change in the EQ-5D-3L, EQ-5D-5L, and HUI3, over three different time periods, in a sample of people with prescription-type opioid use disorder. Whether comparing group mean estimates or using methods that employ the full distribution of responses, no instrument consistently outperformed the others.Our finding of no superior instrument aligns with the mixed conclusions from previous comparative analyses that focus on changes in health status [Non-significant differences between ‘improved’ and ‘not improved’ groups were more frequent for the condition-specific anchors—eight of nine analyses for the Brief Substance Craving Scale, one of three analyses for the Clinical Opiate Withdrawal Scale—which likely reflects less of a conceptual overlap with the preference-based instruments (compared with domain-specific and generic anchors). The observation of weaker sensitivity of the index scores to changes in the two condition-specific anchors may also be due, partly, to the misaligned administration of measures. For example, Brief Substance Craving Scale scores at week 10 and week 22 were paired with week 12 and week 24 index scores, respectively (exploratory analyses of the trial data has shown the stability of Brief Substance Craving Scale scores from week 6 onward [The inclusion of near-identical items provided an opportunity to apply data quality checks. At each time point, at least 24% of participants violated a data quality condition; when adopting the strict data quality criteria, sample sizes for analyses by time period were reduced by over 40%. The observation that data quality violations were more common in racialized participants warrants further investigation. While this statistically significant finding may be spurious—a consequence of multiple testing [Strengths of the study include the use of responses to three widely used preference-based HRQoL instruments (including the first use of the HUI3 in the context of opioid use disorder), all with preference weights derived from individuals from the same country (Canada); examination of instruments’ ability to capture change using different methodological approaches (ROC curves and group mean comparisons) across three time periods; and comprehensive consideration of data quality. As with all studies, there are limitations, and caution is advised when generalizing findings beyond the study population. For example, the data-intensive nature of examining change resulted in a significant proportion of participants from the data source (the trial) being excluded from the analysis. The primary limitation was the absence of relevant published MID estimates for the anchors (or questions about self-perceived changes in general health in the study surveys). Instead, distribution-based methods were used, which ensure there are differences in the degree of change between groups but make no judgment about whether these differences are clinically meaningful. In extolling the universality of the ‘half a standard deviation’ distribution-based approach, Norman and colleagues state that it “