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Abstract Background Breast cancer is one of the most common cancers in women. Patient-reported outcome measures are used to evaluate patients’ health-related quality of life in clinical breast cancer studies. This study evaluated the structure, validity, reliability, and responsiveness of the National Comprehensive Cancer Network-Functional Assessment of Cancer Therapy-Breast Cancer Symptom Index (NFBSI-16) subscales in a clinical trial featuring patients with advanced/metastatic breast cancer (aBC), and estimated NFBSI-16 meaningful change thresholds. Methods Data from 101 patients with aBC enrolled in a phase II trial (Xenera-1) were included for psychometric evaluation of the NFBSI-16. Subscale structure was evaluated by assessing inter-item correlations, item-total correlations, and internal consistency (cycles 2 and 5). Validity was assessed using scale-level convergent validity (cycles 2 and 5) and known-groups (Baseline). Reliability was analysed via test-retest at cycles 3–4, and responsiveness to improvement and worsening was evaluated at cycles 5, 7, and 9. Meaningful change thresholds were estimated using anchor-based methods (supported by distribution-based methods) at cycles 5, 7, and 9. Results NFBSI-16 internal consistency was acceptable, but item-total correlations suggested that its subscales and the GP5 item (side-effect of treatment) scores may be preferred over a total score. Convergent and known-groups evidence supported NFBSI-16 validity. Test-retest reliability was good to excellent for Total and DRS-P (disease-related symptoms: physical) scales, and moderate for the GP5 item. Responsiveness to worsening was generally demonstrated, but responsiveness to improvement could not be demonstrated due to limited observed improvement. Anchor-based meaningful change thresholds were estimated for DRS-P and Total scores. Conclusion This study provides evidence that the NFBSI-16 has desirable psychometric properties for use in clinical studies in aBC. It also provides estimates of group- and individual-level meaningful change thresholds to facilitate score interpretation in future aBC research.

Tinnitus Severity and Tinnitus Distress are frequently referenced and conflated constructs in research, measured using established tinnitus patient-reported outcome measures (PROs). Confusion regarding these constructs and their relation to fundamental scientific conceptions of tinnitus represents a threat to the validity of PROs as applied in tinnitus research, the conclusions that are reached when applying them, and subsequent progress of theory and clinical interventions for those experiencing tinnitus. Therefore, we critically review relevant literature, providing the Severity of Symptoms (SoS) and Correlates of Complaint (CoC) framework to link tinnitus theory to these constructs. We provide researchers with an overview of latent variable fundamentals (including distinctions between formative and reflective measures, and psychometric and clinimetric measurement traditions). We then provide a synthesis of the relationship between Tinnitus Severity and Tinnitus Distress, the SoS/CoC framework, and latent variable measurement to elucidate their distinctions. Finally, we take the Tinnitus Handicap Inventory (THI) as an exemplar of established tinnitus PROs and use study data (N = 200) to empirically evaluate the appropriateness of the THI as a reflective measure of Tinnitus Distress. Subsequently, conceptual and criterion mediation tests provide evidence that the THI is not a reflective measure of Tinnitus Distress according to the CoC conception and should be considered as a formative measure. Researchers should therefore consider whether established tinnitus PROs, such as the THI, are congruent with the scientific conceptions and subsequent theories that they aim to evaluate.

This study presents the executive disruption model (EDM) of tinnitus distress and subsequently validates it statistically using two independent datasets (the Construction Dataset: n = 96 and the Validation Dataset: n = 200). The conceptual EDM was first operationalised as a structural causal model (construction phase). Then multiple regression was used to examine the effect of executive functioning on tinnitus-related distress (validation phase), adjusting for the additional contributions of hearing threshold and psychological distress. For both datasets, executive functioning negatively predicted tinnitus distress score by a similar amount (the Construction Dataset: β = −3.50, p = 0.13 and the Validation Dataset: β = −3.71, p = 0.02). Theoretical implications and applications of the EDM are subsequently discussed; these include the predictive nature of executive functioning in the development of distressing tinnitus, and the clinical utility of the EDM.