FACT-8D, a novel cancer-specific, preference-based measure of health, derived from the Functional Assessment of Cancer Therapy – General (FACT-G) questionnaire, may offer an alternative method to generate utilities for the cost-effectiveness analysis of cancer treatments (J Patient Rep Outcomes. 2020 Mar 27;4(1):22).
“The FACT-8D’s measurement properties have not been tested to date,” explained Michael Herdman, Office of Health Economics, London, United Kingdom, and colleagues, leading them to conduct a blinded analysis of pooled data from a phase 3 trial of patients with relapsed/refractory mantle cell lymphoma (MCL) in order to assess its validity and responsiveness, as well as compare these results to the EQ-5D-5L.
FACT-8D baseline and follow-up data were scored using Australian preference weights (the first available value-set). Convergent validity was assessed by estimating baseline correlations with the FACT-Lym total score, Trial Outcome Index (TOI), FACT-Lym lymphoma-specific sub-scale (LymS), EQ-5D Visual Analog Scale (VAS), and hemoglobin (HgB).
In order to test known groups’ validity, relevant clinical variables were used to categorize patients. Responsiveness was assessed using data from baseline (n = 250) and week 31 (n = 130). Results were compared with EQ-5D-5L and scored using the UK 3L crosswalk and the 5L England value-sets.
Overall, researchers noted that FACT-8D demonstrated good convergent validity and responsiveness. Baseline Pearson correlation coefficients between FACT-8D Index scores and other PRO measures were moderate to very strong (range: 0.49 for EQ-VAS to 0.79 for FACT TOI). The change in FACT-8D Index scores at week 31 differed significantly (P <0.005) between patients categorized as improved, worsened, or stable using the FACT-Lym total score, LymS, and HgB.
However, FACT-8D failed to discriminate between patients categorized by health status on 4 of the 7 variables analyzed when assessing the known groups’ validity.
In the comparative analysis of FACT-8D with EQ-5D-5L, the 2 health utility measures performed similarly, although researchers noted that EQ-5D-5L demonstrated better known groups’ validity compared to FACT-8D.
“In this RR MCL trial dataset, [FACT-8D] showed good convergent validity and responsiveness, but poorer known groups’ validity, and EQ-5D performed as well or better on the tests conducted. The FACT-8D may offer an alternative method to generate utilities for the cost-effectiveness analysis of cancer treatments but needs further testing in other types of cancer patients,” Mr Herdman and colleagues concluded, adding that the evaluation of utility gains may have been limited by high baseline performance status in this trial sample.—Janelle Bradley
