Presentation (CTI)

OBJECTIVES: Single-item ordinal patient-reported outcome endpoints can be clinically meaningful but require a different validity argument than multi-item scales. In IRAKLIA, a phase 3 trial (NCT05405166) of patients with relapsed/refractory multiple myeloma, satisfaction with injection method since the last visit was assessed using Patient Experience and Satisfaction Follow-up Questionnaire (PESQ-FU) Item 8, a 5-point ordinal item. Using pooled Cycle 5 Day 15 data from both arms (N=392), we applied complementary methods to evaluate whether this satisfaction measure functions as an interpretable, experience-driven endpoint.
METHODS: Traditional psychometric analyses evaluated response distribution, item-to-item correlations, known-groups validity, and test-retest reliability. A staged analytic plan prespecified logistic regression first; its findings then informed prespecified structural equation modeling (SEM) and network analyses. Ordinal logistic regression modeled higher satisfaction (three ordered categories) as a function of injection discomfort, pain, injection-method side effects, time saved, baseline expectations, and demographic/clinical covariates. SEM specified discomfort, pain, and injection side effects as indicators of a latent Injection Experience construct, while time saved was modeled separately. Partial-correlation network analysis evaluated direct relationships between satisfaction and other PESQ-FU and broader health-related quality of life variables.
RESULTS: Correlations supported associations with theoretically relevant experience indicators, particularly time saved and pain. In multivariable regression, time saved was the strongest independent predictor of higher satisfaction, followed by pain and injection-method side effects; apart from baseline expectations for time saved, demographic/clinical covariates were not associated after adjustment. SEM supported the hypothesized structure, with excellent fit and independent contributions of time saved and Injection Experience. Network analyses provided complementary evidence, with satisfaction directly connected to saved time and pain.
CONCLUSIONS: A triangulated approach combining psychometric, regression, SEM, and network evidence supported PESQ-FU Item 8 as a fit-for-purpose, experience-driven satisfaction endpoint. These findings illustrate how complementary quantitative methods can collectively support a validity argument for conceptually meaningful single-item ordinal PRO endpoints.