Japanese value set for the Functional Assessment of Cancer Therapy Eight Dimension (FACT-8D) cancer-specific preference-based quality of life instrument

TL;DR

This study created a Japanese version of the FACT-8D tool, which measures cancer patients' quality of life in a way that can be used to calculate quality-adjusted life years.

Contribution

The study provides a new Japanese value set for the FACT-8D instrument using a population-based discrete choice experiment.

Findings

The Japanese value set showed that Pain and Nausea had the strongest negative impact on health utilities.

The worst health state in Japan scored -0.60, significantly lower than in other countries like the UK and Australia.

The study confirmed the feasibility of deriving health utilities from the widely used FACT-G questionnaire.

Abstract

The Functional Assessment of Cancer Therapy General (FACT-G) questionnaire is frequently used to assess health-related quality of life (HRQOL) in cancer patients. However, data obtained using the FACT-G cannot be directly used to calculate quality-adjusted life years (QALYs). The newly developed FACT Eight Dimensions (FACT-8D) is a preference-based measure that generates health utilities scores from 9 of the 27 FACT-G items, representing eight HRQOL domains (Nausea, Pain, Fatigue, Sleep, Work, Worry, Sadness, Support from family/friends). This study aimed to create a Japanese FACT-8D value set.

A cross-sectional online survey of the Japanese general population recruited participants via a Japanese online panel, quota sampled by age (≥ 18 years) and sex. FACT-8D valuation data were collected with a discrete choice experiment. The valuation task required each participant to consider 16 pairs of hypothetical health states, randomly assigned per participant from 800 choice-sets. Preference weights were obtained from conditional logit models by dividing estimated HRQOL coefficients by the life duration coefficient.

Data from 2320 participants were used to assess sample representativeness and estimate the Japanese value set. All preference weights other than Worry Level 2 were negative and increased in absolute terms in progressively higher levels of adverse HRQOL impact. The most influential domains for health utilities were Pain and Nausea, followed by Work problems. Fatigue, Sleep, Support, Sadness, and health Worry had moderate influences on health utilities. The lowest score, for the pit state [55555555], was − 0.60. This value is much lower than that of the EORTC QLU-C10D pit state [4444444444], -0.22. Health states were consistently scored higher in the USA, Australia and the UK than in Japan. Canadian health states are generally lower than for Japan, but not universally so.

We established the Japanese FACT-8D value set based on the internationally common protocol. The value set provides another option for quantifying health utilities for cancer outcomes. This contributes to improving the feasibility of deriving health utilities from the widely used FACT-G.

The online version contains supplementary material available at 10.1186/s12955-025-02442-3.

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