Abstract
BACKGROUND: Thyroid cancer incidence is increasing. The effect of diagnosis and treatment on health-related quality of life (HRQoL) is an essential variable in the absence of a change in life span for the majority of patients. HRQoL instruments, with data useful for between-disease comparisons, are being increasingly used for health policy and outcomes evaluation. Variation exits among the instruments based on the impact of a specific disease. We assessed which of four well-validated, preference-based surveys detect changes in health and clinical intervention in patients diagnosed with papillary thyroid cancer (PTC). METHODS: Four commonly used HRQoL questionnaires (Short Form-12v2® [SF6D], EuroQol-5D [EQ5D], and Health Utilities Index Mark 2 and 3 [HUI2, HUI3]) were administered to patients with the diagnosis of PTC at three perioperative time points during the first year of treatment. Clinicopathological and treatment course data were assessed for HRQoL impact including complications from surgery, re-operation for persistence/early recurrence, and adjuvant radioactive iodine treatment. We compared standard metrics, including ceiling effect, intraclass correlation coefficient, effect sizes, and quality-adjusted life-years between the four instruments. RESULTS: Of 117 patients, 27% had a preoperative diagnosis of anxiety or depression, 41% had regional lymph node metastases, three had distant metastases and 49% underwent adjuvant radioactive iodine treatment. The ceiling effect (i.e., proportion with a perfect score) was greatest with EQ5D and least with SF6D. Index scores ranged from 0.77 (SF6D) to 0.90 (EQ5D). All scores declined at two weeks postoperatively and returned to pretreatment levels at six months. The SF6D was the only instrument to exceed the conventional minimally important difference between all three time points. Quality-adjusted life-years were as follows: SF6D, 0.79; EQ5D, 0.90; HUI2, 0.88; and HUI3, 0.86. CONCLUSIONS: Our results reflect the general good health of PTC patients. The effect on quality of life is primarily related to emotional and social impacts of treatment. The results support the measurement of a similar underlying construct, although variation in detecting changes in health exists between the instruments. Of the instruments assessed, the SF6D is the most responsive to treatment effects and should be utilized in future economic analyses in this patient population.