APPLICABILITY AND PSYCHOMETRIC EVALUATION OF UTILITY AND CANCER-SPECIFIC HEALTH-RELATED QUALITY OF LIFE MEASURES IN PATIENTS WITH INCIDENTAL THYROID NODULES

Purpose: The aim of this study was to examine the acceptability, validity and reliability of utility measures and cancer-specific health-related quality of life (HRQOL) in Chinese patients diagnosed with incidental thyroid nodules.

Method(s): Data from a randomized controlled trial (ClinicalTrials.gov Identifier: NCT02398721) of 314 patients diagnosed with incidental thyroid nodules were utilized for this psychometric evaluation of HRQOL measurement. Three HRQOL questionnaires, cancer-specific Functional Assessment of Cancer Therapy-general (FACT-G) and generic 12-item Short Form Health Survey (SF-12v2) and 6-item Short Form Health Survey (SF-6D), were administered through face-to-face interviews at both baseline and 2-week after baseline. Responses to SF-6D were transformed to SF-6D utility scores using Hong Kong standard gamble value set. Construct validity was determined by evaluating the extent to overlap SF-12v2 dimensions across HRQOL instruments by Spearman rank correlation. Internal consistency and 2-week test-retest reliability was assessed using Cronbach’s α coefficient and intra-class correlation coefficient, respectively.

Result(s): No significant (>15%) floor and ceiling effects were observed for FACT-G subscale and total scores. The SF-6D utility scores and FACT-G subscale scores had a moderate Spearman rank correlation with the corresponding SF-12v2 domain score that conceptually measures the similar construct providing evidence for adequate construct validity. Internal consistency of the FACT-G subscales and total scales were acceptable (α: 0.639-0.850) for all subscales aside from the Emotional well-being subscale (α: 0.581). The HRQOL and utility scores showed excellent test-retest reliability (range: 0.758-0.858).

Conclusion(s): The SF-6D utility score and cancer-specific FACT-G questionnaire appears to be a valid and reliable measure to assess the HRQOL of Chinese patients diagnosed with incidental thyroid nodules, and thus evaluate the treatment response to those patients.