Proxy reporting of health-related quality of life for people with dementia: a psychometric solution

Understanding the influence of different proxy perspectives in explaining the difference between self-rated and proxy-rated quality of life in people living with dementia: a systematic literature review and meta-analysis

PURPOSE

Proxy assessment can be elicited via the proxy-patient perspective (i.e., asking proxies to assess the patient's quality of life (QoL) as they think the patient would respond) or proxy-proxy perspective (i.e., asking proxies to provide their own perspective on the patient's QoL). This review aimed to identify the role of the proxy perspective in explaining the differences between self-rated and proxy-rated QoL in people living with dementia.

METHODS

A systematic literate review was conducted by sourcing articles from a previously published review, supplemented by an update of the review in four bibliographic databases. Peer-reviewed studies that reported both self-reported and proxy-reported mean QoL estimates using the same standardized QoL instrument, published in English, and focused on the QoL of people with dementia were included. A meta-analysis was conducted to synthesize the mean differences between self- and proxy-report across different proxy perspectives.

RESULTS

The review included 96 articles from which 635 observations were extracted. Most observations extracted used the proxy-proxy perspective (79%) compared with the proxy-patient perspective (10%); with 11% of the studies not stating the perspective. The QOL-AD was the most commonly used measure, followed by the EQ-5D and DEMQOL. The standardized mean difference (SMD) between the self- and proxy-report was lower for the proxy-patient perspective (SMD: 0.250; 95% CI 0.116; 0.384) compared to the proxy-proxy perspective (SMD: 0.532; 95% CI 0.456; 0.609).

CONCLUSION

Different proxy perspectives affect the ratings of QoL, whereby adopting a proxy-proxy QoL perspective has a higher inter-rater gap in comparison with the proxy-patient perspective.

Development of consensus-based considerations for use of adult proxy reporting: an ISOQOL task force initiative

AIMS

Many large-scale population-based surveys, research studies, and clinical care allow for inclusion of proxy reporting as a strategy to collect outcomes when patients are unavailable or unable to provide reliable self-report. Prior work identified an absence of methodological guidelines regarding proxy reporting in adult populations, including who can serve as a proxy, and considerations for data collection, analysis, and reporting. The primary objective of this work by the ISOQOL Proxy Task Force was to review documents and clinical outcome assessment measures with respect to proxy reporting and to develop, through consensus, considerations for proxy reporting.

METHODS

We assembled an international group with clinically relevant and/or methodological expertise on proxy use in adult populations. We conducted a targeted review of documentation based on regulatory, non-regulatory, professional society, and individual measure sources. Using a standardized collection form, proxy-related information was extracted from each source including definitions of a proxy, characteristics of a proxy, domains addressable or addressed by a proxy, and observer-reporting.

RESULTS

The definition of proxy was inconsistent across 39 sources, except regulatory documents which defined a proxy as a person other than the patient who reports on an outcome as if she/he were the patient. While proxy report was discouraged in regulatory documentation, it was acknowledged there were instances where self-report was impossible. Many documentation sources indicated proxies would be well-justified in certain contexts, but did not indicate who could act as a proxy, when proxies could be used, what domains of patient health they could report on, or how data should be reported. Observer-reported outcomes were typically defined as those based on observed behaviors, however there was not a consistent differentiation between proxy and observer reporting. Based on information extracted from these resources, we developed a checklist of considerations when including proxy-reported measures or using proxies in study design, data collection, analysis, interpretation and reporting of proxy reported data.

CONCLUSION

Our targeted review highlights a lack of clarity in capturing, interpreting and reporting data from proxies in adult populations. We provide a checklist of considerations to assist researchers and clinicians with including proxies in research studies and clinical care. Lastly, our review identified areas where further guidance and future research are necessary.

Psychometrics of the Physical Resilience Scale in Older Adults Living with Dementia: Proxy Responses

Objectives: The purpose of this study was to determine if proxies can complete the Physical Resilience Scale for older adults living with dementia. Methods: This was a descriptive study using Rasch analysis and baseline data from the Function Focused Care for Acute Care Using the Evidence Integration Triangle trial. The first 240 patients living with dementia were included in this analysis. Results: There was evidence of reliability based on person and item separation index. There was no evidence of Differential Item Functioning (DIF) between genders and a DIF by race on Item 7. Validity was supported based on items fitting the model with the exception of one item, and a significant relationship between physical resilience and pain and function. Discussion: There is some evidence that the Physical Resilience Scale is reliable and valid when completed by proxy reports. Future use should remove one of the items due to redundancy.

Convergent validity of EQ-5D with core outcomes in dementia: a systematic review

Objectives

To explore through a systematic review, the convergent validity of EQ-5D (EQ-5D-3L and EQ-5D-5L (total score and dimensions)) with core outcomes in dementia and investigate how this may be impacted by rater-type; with the aim of informing researchers when choosing measures to use in dementia trials.

Methods

To identify articles relevant to the convergent validity of EQ-5D with core dementia outcomes, three databases were electronically searched to September 2022. Studies were considered eligible for inclusion within the review if they included individual level data from people with dementia of any type, collected self and/or proxy reported EQ-5D and collected at least one core dementia outcome measure. Relevant data such as study sample size, stage of dementia and administration of EQ-5D was extracted, and a narrative synthesis was adopted.

Results

The search strategy retrieved 271 unique records, of which 30 met the inclusion criteria for the review. Twelve different core outcome measures were used to capture dementia outcomes: cognition, function, and behaviour/mood across the studies. Most studies used EQ-5D-3L (n = 27). Evidence related to the relationship between EQ-5D and measures of function and behaviour/mood was the most robust, with unanimous directions of associations, and more statistically significant findings. EQ-5D dimensions exhibited associations with corresponding clinical outcomes, whereby relationships were stronger with proxy-EQ-5D (than self-report).

Conclusion

Measuring health-rated quality of life in dementia populations is a complex issue, particularly when considering balancing the challenges associated with both self and proxy report. Published evidence indicates that EQ-5D shows evidence of convergent validity with the key dementia outcomes, therefore capturing these relevant dementia outcomes. The degree of associations with clinical measures was stronger when considering proxy-reported EQ-5D and differed by EQ-5D dimension type. This review has revealed that, despite the limited targeted psychometric evidence pool and reliance on clinical and observational studies, EQ-5D exhibits convergent validity with other dementia outcome measures.

Do we agree or disagree? A systematic review of the application of preference-based instruments in self and proxy reporting of quality of life in older people

PURPOSE

Quality of life is an important person-centred outcome in health and aged care settings. Due to an increasing prevalence of cognitive decline and dementia in ageing populations, a proportion of older people receiving health and aged care services may not be able to reliably assess their own quality of life, highlighting the need for proxy assessment. This systematic review sought to investigate the level of agreement between self and proxy-report of older people's quality of life using established preference-based instruments of quality of life suitable for economic evaluation.

METHODS

A systematic review was conducted following PRISMA guidelines. Eight databases were searched: Web of Science, Scopus, Medline, Econlit, PsychINFO, CINAHL, Ageline and Cochrane Library. Information was extracted on the instruments, population samples (including any cognitive thresholds applied), mean scores, type of proxy, and measures of inter-rater agreement.

RESULTS

A total of 50 studies using eight different preference-based quality of life instruments were identified. Most studies were cross-sectional (72%) with a wide variety of cognitive assessments and thresholds applied to define older participants with cognitive impairment. The most common proxies were family members, mostly spouses. The level of agreement between self and proxy-report was generally poor - irrespective of the instrument applied or type of proxy - with proxy-report generally indicating lower levels of quality of life than self-report. There was some evidence of stronger agreement on more observable quality of life domains e.g., physical health and mobility, relative to less observable domains e.g. emotional well-being. Few studies tracked self and/or proxy-report of quality of life longitudinally.

CONCLUSIONS

More research is needed to develop evidence to inform guidance on self-report versus proxy-report of quality of life for older people receiving health and aged care services. Until then, the collection of both self and proxy reports as complementary measures is indicated.

FACE-Q Craniofacial Module: Part 1 validation of CLEFT-Q scales for use in children and young adults with facial conditions

BACKGROUND

The CLEFT-Q includes 12 independently functioning scales that measure appearance (face, nose, nostrils, teeth, lips, jaws), health-related quality of life (psychological, social, school, speech distress), and speech function, and an eating/drinking checklist. Previous qualitative research revealed that the CLEFT-Q has content validity in noncleft craniofacial conditions. This study aimed to examine the psychometric performance of the CLEFT-Q in an international sample of patients with a broad range of facial conditions.

METHODS

Data were collected between October 2016 and December 2019 from 2132 patients aged 8 to 29 years with noncleft facial conditions. Rasch measurement theory (RMT) analysis was used to examine Differential Item Function (DIF) by comparing the original CLEFT-Q sample and the new FACE-Q craniofacial sample. Reliability and validity of the scales in a combined cleft and craniofacial sample (n=4743) were examined.

RESULTS

DIF was found for 23 CLEFT-Q items when the datasets for the two samples were compared. When items with DIF were split by sample, correlations between the original and split person locations showed that DIF had negligible impact on scale scoring (correlations ≥0.995). In the combined sample, RMT analysis led to the retention of original content for ten CLEFT-Q scales, modification of the Teeth scale, and the addition of an Eating/Drinking scale. Data obtained fit with the Rasch model for 11 scales (exception School, p=0.04). Person Separation Index and Cronbach alpha values met the criteria.

CONCLUSION

The scales described in this study can be used to measure outcomes in children and young adults with cleft and noncleft craniofacial conditions.