Abstract
BackgroundThe FACT-8D is a new cancer-specific, preference-based measure (PBM) of health, derived from the Functional Assessment of Cancer Therapy – General (FACT-G) questionnaire. The FACT-8D’s measurement properties have not been tested to date. We assessed it’s validity and responsiveness in relapsed/refractory mantle cell lymphoma (RR MCL) and compared the results to the EQ-5D-5L.MethodsBlinded analysis of pooled data from a phase 3 clinical trial. FACT-8D baseline and follow-up data (weeks 4, 7, 16, 31) 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 haemoglobin (HgB). Relevant clinical variables were used to categorise patients to test known groups’ validity and responsiveness was investigated using data from baseline (n = 250) and week 31 (n = 130). Results were compared with EQ-5D-5L, scored using the UK 3L crosswalk and the 5L England value-sets.ResultsThe FACT-8D showed 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 the EQ-VAS to 0.79 for FACT TOI) and the size of the change in FACT-8D Index scores at week 31 differed significantly (p < 0.005) between patients categorised as improved, worsened or stable using the FACT-Lym total score, LymS, and HgB. However, when assessing known groups’ validity, FACT-8D failed to discriminate between patients categorised by health status on four of the seven variables analysed. Overall, FACT-8D and EQ-5D-5L performed similarly, although EQ-5D-5L showed better known groups’ validity.ConclusionsThis is the first investigation into the psychometric properties of the FACT-8D. In this RR MCL trial dataset, it 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. Evaluation of utility gains may have been limited by high baseline performance status in this RR MCL trial sample.
Highlights
Generic preference-based measures (PBMs) of patientreported health, the EQ-5D, form the cornerstone of health-related quality of life (HRQOL) measurement for economic evaluation in the context of health technology assessment [1, 2]
Evaluation of utility gains may have been limited by high baseline performance status in this RR Relapsed/refractory mantle cell lymphoma (MCL) trial sample
On Functional Assessment of Chronic illness Therapy (FACT)-8D at baseline, problems were most frequently reported on the work (87% reporting problems) and sleep (80%) dimensions, and least frequently on the nausea dimension (17%). 71.8% of patients reported some degree of fatigue
Summary
Generic preference-based measures (PBMs) of patientreported health, the EQ-5D, form the cornerstone of health-related quality of life (HRQOL) measurement for economic evaluation in the context of health technology assessment [1, 2]. In recent years, several condition-specific PBMs have been developed which could be used in economic evaluations, including instruments designed to derive health utilities in cancer [4], overactive bladder [5], epilepsy [6], or asthma [7]. As condition-specific questionnaires assess aspects of HRQOL which are of particular relevance to a given patient population, they might be expected to be more valid and sensitive in those patients than generic measures. In this regard, the EQ-5D has occasionally been criticised as insensitive and unresponsive to differences and changes in health status in some conditions, including cancer, often without empirical evidence to support such claims [8]. We assessed it’s validity and responsiveness in relapsed/refractory mantle cell lymphoma (RR MCL) and compared the results to the EQ-5D-5L
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