Preference-based measures of health-related quality of life in Indigenous people: a systematic review

Preference-based measures (PBMs) are surveys that help us understand the quality of life related to health of people or groups. These surveys are essential for making decisions about healthcare approaches and health policies. It is crucial that the PBMs accurately and consistently assess health for a person or group. Currently we lack a summary of information on how PBMs are used specifically for Indigenous people and whether these surveys effectively capture their health experiences. This is particularly important because Indigenous communities worldwide have unique knowledges and approaches to healing that promote their health and care experiences. To address this gap, we reviewed published information to understand how PBMs are used with Indigenous people. Our study shows that PBMs have been used more and more with Indigenous people even though there is not much information on how well these surveys work in this group. This finding highlights the need for further discussions and research on how to measure health-related quality of life accurately and meaningfully for Indigenous people.

Preference-based measures provide a measurement of health-related quality of life (HRQL) that can be used to evaluate individual or population health. PBM allow us to calculate value or utility of different health states, which are used in calculating quality-adjusted life years (QALYs) used in economic evaluations. There are two types of PBMs: direct and indirect. Direct PBMs, such as time trade-off or standard gamble, typically ask respondents to make choices about hypothetical health scenarios [1] under conditions of certainty or uncertainty. On the other hand, indirect PBMs use a classification system describing specific dimensions of health, and a scoring system, to infer preferences for a particular health state based on previously elicited values usually from the general population [1]. Indirect generic PBMs (such as the EQ-5D-5L) permit comparison across different populations, whereas indirect condition-specific PBMs (such as the cancer-specific EORTC-QLQ-C30) can be more useful in disease-specific healthcare areas [1].

The usefulness of a PBM is partially contingent on the appropriateness of the PBM for the population in which it is used. Many Indigenous groups hold a worldview and conceptualization of health [2] that may not be reflected in current instruments that have been translated or adapted to non-Indigenous contexts. Indigenous people face distinct health needs and experience significant health inequalities [3‐6], often stemming from the negative impacts of colonial systems [7]. There is a need to improve appropriateness of health care services and measures of disease for Indigenous populations [6]. This means ensuring that PBMs consider the specific cultural contexts, values, and health perspectives of Indigenous communities. It is not only an ethical imperative but also a priority for population health to establish the validity and reliability of PBMs in Indigenous populations.

There is limited evidence on the use of PBMs with Indigenous people, and their alignment with Indigenous worldviews. A systematic review of literature conducted in 2016 [8] identified only one PBM—the EQ-5D 3-level version (EQ-5D-3L) which has been preliminarily validated for use in Māori in New Zealand [9]. Upon conducting a more recent and expanded scoping review (March 2020), we identified an additional seven studies using PBMs with Indigenous people. These studies had various aims including measurement of HRQL, validation of PBMs, and direct valuation of health states [10‐16]. We felt it pertinent to conduct an updated and expanded systematic review on the use of PBMs with Indigenous people, globally.

The objective of this review was to identify, summarize, and appraise the literature reporting the use of direct or indirect PBMs with Indigenous people in terms of (1) assessing measurement properties of PBMs, (2) eliciting health preferences using a direct PBM, (3) reporting development or translation of a PBM for Indigenous Peoples, or (4) measuring HRQL using a PBM.

Our review identified a substantial number of recent publications from diverse research areas that reported the use of PBMs with Indigenous people worldwide. This review also demonstrates that a wide variety of PBMs have been used to report health status, despite relatively little (or, in some cases, lack of) evidence on their performance in various Indigenous populations. Similarly, studies investigating translation or development of PBMs and preference elicitation were nearly absent, or in their early stages, often published as protocols. Studies involving Indigenous people were predominantly conducted in Australia and New Zealand, followed by the USA and Canada. There were only two reports exploring traditional direct preference elicitation methods (TTO or SG), while the majority of reports used indirect, multi-attribute PBM, the most common of which was the EQ-5D.

To our knowledge, this is the first systematic review to specifically explore the use of PBMs with Indigenous people, shedding light on their current application. Given the recent and relative increase in the number of studies reporting PBMs with Indigenous people, understanding performance metrics in this population is essential. Apart from a recent study of validity and reliability of the EQ-5D-5L for Indigenous Australians [52], studies evaluating performance are more than ten years old, presenting a possibly dated perspective of any of these instruments which have evolved to newer versions. Guidelines suggest first evaluating content and face validity of an instrument, followed by internal structure (construct validity), criterion validity, reliability and responsiveness [107]. Given this, it appears that for most colonized countries, a comprehensive evaluation of the performance of any PBM with Indigenous people should be done before using PBMs with these populations. COSMIN’s guidance further affirms the need to start with exploration of content validity and other forms of validity for any PBM that may be used to measure HRQL with Indigenous people [108].

There is a significant and growing body of Indigenous research and work published in academic journals that shares Indigenous perspectives on health, wellness, quality of life, and health related quality of life [2, 109‐111]. This includes development of Aboriginal or Indigenous specific HRQL measures, such as the Aboriginal Children’s Health and Wellbeing Measure [112, 113]. It also includes accounts of what current PBMs of health-related quality of life (based on western biomedical models of health) fail to capture, such as elements of community, the environment, or spirituality [2, 29, 64, 110, 111, 114]. This review provides preliminary evidence of dimensions of health that may not be adequately captured for Maori people [64], as well as for Aboriginal and Torres Strait Islander people [103], emphasizing the need to integrate this knowledge into the exploration of validity and development of PBMs that are appropriate, accurate, valid, and reliable for Indigenous Peoples.

We did not find many reports related to the development or translation of PBMs to Indigenous contexts—Jelsma et al. [41] studied the performance of a Xhosa translation of the EQ-5D in South Africa, but the scarcity of translation exercises is noted. In communities in which traditional Indigenous language is still the primary language, translation of PBMs may be an important strategy to include traditional language speakers. Both Arrow et al. [10] and Howard et al. [104] proposed studies to develop a dental specific health utility scale and a preference-based wellbeing measure (respectively) in Australia. There are also recent efforts being made to generate an Indigenous specific PBM using Indigenous or decolonizing methodologies [64, 103, 104]. This approach should be modeled in the pursuit of similar questions around developing PBMs in other colonized countries. However, if Indigenous-specific HRQL instruments exist, perhaps there is an opportunity to investigate the appropriateness of deriving preferences for existing Indigenous-specific instruments.

The review by Angell et al. [8] focused on measures of HRQL with Indigenous people, but only captured one PBM. There are multiple factors that may have contributed to this recent increase. Firstly, there is a growing demand and interest in the application of PBMs in general, as they have become a common metric in evaluation of health and health system performance. Additionally, the global focus on reconciliation efforts prompted a shift in research practices to recognize, include, and partner with Indigenous people, aiming to address historic harms. The increasing number of studies in this review involving or reporting Indigenous people may be a result of this political and organizational shift towards engagement and reconciliation. In any case, we believe the inclusion of Indigenous people in studies using and reporting on PBMs is a beginning to the necessary representation and power shift in how research on PBMs is conducted or reported in Indigenous communities.

It is important to note that the majority of reports in this review did not clearly indicate whether the work was undertaken using currently accepted approaches for ethically engaged Indigenous research. Engaged approaches can reflect researchers' intentionality and their acknowledgment (or lack thereof) of the historical harms that colonizing research practices have inflicted upon Indigenous people. The lack of reporting likely calls for ongoing efforts to increase knowledge, awareness, and training in ethically engaged Indigenous research. It is also possible that academic journals publishing on PBMs are based in positivist epistemologies and are still maturing in their willingness and ability to include detailed information on engaged scholarship. Consequently, the records we found may not have provided comprehensive details regarding the methodology, particularly in terms of the extent of engagement with Indigenous communities.

PBMs, such as the EQ-5D, have already been adopted by some health systems to support health care resource allocation and economic evaluation [115]. The limited amount of recent information on performance of PBMs with Indigenous people suggests that the use of PBMs with Indigenous people should be applied with caution, and warrants consultation with Indigenous Peoples. There is recent, ethically engaged evidence of both validity (content, construct, criterion) and internal consistency of the EQ-5D-5L in Aboriginal and Torres Strait Islanders [52]. However, although this may indicate support for the EQ-5D-5L (at least in Aboriginal and Torres Strait Islanders), the authors also explicitly state that content validity was endorsed “in the absence of another suitable instrument being available” [52]. This aligns with concerns nearly two decades earlier about construct validity in Māori [9] that may suggest further exploration of fundamental questions of validity, and what constitutes health for Indigenous people. Decision-makers and policymakers may wish to exercise caution in their choice of PBM, and if they choose the EQ-5D, consider the transferability of Ribeiro’s findings to specific Indigenous communities in their region.

We undertook a very broad search strategy, in terms of populations, measures, study objectives and designs, intending to understand the full scope of use of PBMs with Indigenous populations. However, we were only able to include studies published in English. This review may also have failed to capture studies reporting broader measures of well-being, or studies supporting the early development of measures, such as theoretical or conceptual studies that may have preceded PBM-specific terminology. Due to the diversity of types of studies in this review, however, we chose not to evaluate the quality and strength of the included studies.

This work focused on describing the state of the peer-reviewed literature for PBMs with Indigenous people and explored how Indigenous groups and communities engaged in the work. This resource can be used to inform future work, and how research teams might engage with Indigenous partners in a research agenda on this topic. This review is based on the intention to understand how current PBMs are used and how they perform, such that they can be used, or put aside, appropriately.

This review suggests that further work is required to evaluate the performance of PBMs with Indigenous people. Given the predominant use of indirect PBMs, it is important to assess not only the validity of health status descriptive systems, but also the concept of valuation and preference elicitation. Given the limited evidence on the performance of current PBMs, future research might also focus on development of a PBM from an Indigenous-specific HRQL descriptive system and preference valuation that is culturally appropriate for Indigenous people. Work in this direction should only be pursued in an engaged manner, therefore relationship building between Indigenous communities, health economists and health policy actors would be beneficial. Lastly, exploration of the relevance of the Aboriginal and Torres Strait Islander quality assessment tool to other Indigenous contexts should be explored to support future systematic reviews and assessment of research.

Future research is not without ethical and political obligations for western researchers to recognize spaces for Indigenous self-determination in research, actively engaging in the work of decolonizing current (colonizing) research and policy systems [116, 117]. Similarly, theoretical assumptions of the health economic paradigm itself should be considered in terms of their euro-western roots and documented limitations [118], and the relation to Indigenous ways of knowing and Indigenous approaches to decision-making and priority-setting [119‐121].

PBMs have many applications, including assessment of population health and informing economic evaluation, and therefore resource allocation decisions, in many countries, including Canada. This review provides insight on the current breadth of use of PBMs worldwide with Indigenous people, as well as information on their validity and reliability. Understanding the validity and performance of PBMs with Indigenous populations is particularly important to better understand how such measures, or other measures, might be used in economic analysis that inform resource allocation decisions that affect Indigenous populations. Perhaps most importantly, it is our hope that this review can also facilitate meaningful conversations and work towards accurate and appropriate measurement of HRQL, particularly given the need to address health inequalities experienced by Indigenous people.