Abstract
KEY POINTS
This robustly developed thyroid cancer–specific measure is now available to compare patient outcomes.
The Thyroid Cancer Quality of Life Index provides patient outcome assessment across nine domains.
This measure can be used for health economic evaluations and quality-adjusted life-year–based analyses.
SUMMARY
Background
Many thyroid cancer survivors experience long survivorship and, despite favorable clinical outcomes, can report deficits in long-term physical, psychological, and social functioning, health-related quality of life (HRQoL).1–4 Existing thyroid cancer–specific patient-reported outcome measures (PROMs) comprehensively assess HRQoL 5 but do not allow direct translation into quality-adjusted life-years (QALYs), which are widely used in cost-effectiveness analyses and resource allocation. Generic utility indexes that are commonly used to calculate QALYs lack sensitivity in identifying thyroid cancer–specific HRQoL issues.6,7 This study documents the development and psychometric testing of the Thyroid Cancer Quality of Life Index (TCQOLI), a utility measure for thyroid cancer. 8
Methods
Patients from two U.S. tertiary cancer centers who had a diagnosis of thyroid cancer within the prior 10 years (regardless of point of care) were enrolled from the clinic between March 2021 and September 2025. Non–English speakers and those with a prior history of nonthyroid cancer were excluded. The study was conducted across three phases: (1) domain development, (2) cognitive interviews followed by confirmatory factor, reliability, and other validity analyses, and (3) valuation of health states to utilities. In phase 1, co-investigators (clinicians, survey scientists, and HRQoL methodologists) drew candidate items from existing HRQoL measures including Patient-Reported Outcome Measurement Information System (PROMIS), European Organization for Research and Treatment of Cancer Quality of Life Thyroid Cancer Module 34-item (EORTC QLQ-THY34), Thyroid Cancer Quality of Life measure (24-item, ThyCa-QoL), Functional Assessment of Chronic Illness Therapy—Comprehensive Score for Financial Toxicity (FACIT-COST) measure of financial toxicity, Thyroid Computerized Adaptive Testing (THYCAT), City of Hope Quality of Life Score—thyroid version (COH QOL-TV), and voice handicap index (VHI 10). They obtained permission to use each instrument. For non-PROMIS domains, four candidate questions were developed, and patients were asked to rank these. The importance of the domains was also ranked.
In phase 2, iterative rounds of interviews assessed item relevance, interpretation, clarity, recall, and consistency. This was followed by mixed-methods psychometric assessment including reliability and validity analysis. Finally, in phase 3, health states valuation was undertaken using visual analog scales, standard gamble and anchoring to the most disabled state (death), and full health. Domain importance was ranked and weighted.
Results
There were 10 candidate domains: recurrence concern, appearance, financial hardship, voice problems, swallowing difficulty, reproduction concern, pain interference, depression, fatigue, and cognitive problems.
In phase 2, the most representative single item per domain (as required for utility indexes) was derived after cognitive testing in 50 patients and psychometric survey sample testing in 163 patients (response proportion, 40.6%). The reproduction concern domain had the weakest psychometrics and was ranked least important (even by those ages 21–35 years, it was ranked second-least important). Hence, both the 9- and 10-domain versions were further evaluated. At the full instrument level, only 3.8% of respondents achieved maximum scores (i.e., little ceiling effect), and none scored the minimum (i.e., no floor effect). Psychometrics including factor analysis, reliability, interpretability, and validity were adequate. The valuation sample included 92 patients (38.2% response proportion) who completed visual analog and standard gamble tasks. Multi-attribute utility theory models were fit with good intraclass correlation (0.74).
Conclusions
The TCQOLI has been developed in a psychometrically robust manner and is now available as a brief utility measure for thyroid cancer survivors. Although external validation is required, this tool allows health economic evaluations for thyroid cancer–specific domains.
COMMENTARY
This article represents the summary of an immense body of work to develop TCQOLI. Cunningham and colleagues are to be congratulated on persisting with this comprehensive process despite a pandemic and the health systems disruption that accompanied it. The minimal patient response burden of 9 (or 10) items and the ability to convert the scale to QALYs make this measure an attractive choice to incorporate into clinical practice, registries, and clinical trials.
Modern health systems must ration health care resources according to need. Despite a comparatively good prognosis for most patients with thyroid cancer, there is evidence of HRQoL deficits that are comparable to or worse than malignancies with less favorable clinical outcomes. 9 Because of the younger median age at diagnosis of thyroid cancer, any HRQoL deficits in survivors can have impacts on their societal functioning roles in terms of caregiving and employment, with not just personal but societal economic consequences. The aim of health care should be to maximize holistic outcomes for patients within resource constraints. This index fills a gap in health economic evaluation of thyroid cancer survivors. We especially appreciate that the valuation was done with thyroid cancer patients and not with individuals from the general population, as is often done in health economics.
Health care indexes also allow comparative-effectiveness research with not just clinical but also health economic evaluations. These data are essential to truly evaluate long-term differences in thyroid cancer management strategies, new technologies, and interventions aimed at improving care. Although clinicians may find the psychometric science difficult to digest, it is becoming increasingly important for clinician leaders to have a broad knowledge of health economics. In some health care economies, it has become routine for any clinical or health system innovation to require a cost-effectiveness analysis and business case in addition to demonstration of clinical benefit. The availability of a measure to calculate QALYs can now be utilized to advocate for these types of health care improvements for thyroid cancer survivors.
Although TCQOLI has made every attempt to balance breadth of assessment with brevity (including items of financial toxicity and fear of recurrence, which are omitted from some other measures),10,11 one should keep in mind that utility instruments do not comprehensively assess HRQoL, as this is not their primary purpose. Researchers evaluating HRQoL in thyroid cancer survivors should remain cognizant that a comprehensive and nuanced assessment will require a more detailed tool (or combination of tools) with consideration of assessing unmet needs and qualitative data. For any research study, the selection of HRQoL measures should remain appropriate to the study aims.
Although the authors are to be congratulated on completing such a large body of work, uptake of TCQOLI should be in line with the study limitations. Response proportions at all phases were <50%, likely reflecting the need to adapt enrollment methods for pandemic conditions. Respondents were also predominantly female, White, and well educated, had high-level English skills, and came from only two comprehensive cancer centers (which may see more advanced disease than would be seen in a geographic sample). Moreover, the instrument was developed in only one country.
There is a need for external validation of this tool in broader demographic and international cohorts, perhaps even head to head with existing thyroid cancer–specific PROMs. Nevertheless, the selection and ranking of domains is consistent with the existing evidence base. 12 Despite these limitations, the psychometric development process here is strong, making the TCQOLI an instrument that will be a good fit for many clinical and registry situations internationally. All clinicians should consider how to incorporate such instruments into routine practice.