Evaluating the content validity of generic preference-based measures for use in Parkinson's disease

Confirmatory analysis of the 13-MD and ranking of its meta-dimensions and items

Background

The 13-MD is a new generic instrument developed to measure general health-related quality of life (GHRQoL). This instrument considers all aspects of health (i.e., physical, mental, and social) in a balanced way. A previous study led to minor changes in the original version of the 13-MD. The objective of this study was to confirm the validity of the modified 13-MD.

Methods

Validity was assessed with recent data from the general population of Quebec, Canada. The meta-dimensions and items composing the 13-MD were also subjected to a ranking procedure, which allowed to determine the most important aspects for respondents.

Results

A total of 1337 French-speaking participants were recruited with 1099 completing the 13-MD for validation purposes and 1084 completing the ranking procedure. The 13-MD showed very satisfactory results and confirmed to be a valid instrument. The ranking of the meta-dimensions revealed that "Well-being" received the most points, followed by "Sleep and energy" and "Body functioning."

Conclusion

These results will be very useful in the continuous improvement of the 13-MD, ultimately leading to the valuation stage (i.e., development of a value set).

Cognitive Interviewing to Develop a New Health-Related Quality of Life Measure for Parkinson's Disease: The Preference-Based Parkinson's Disease Index (PB-PDI)

Preference-based measures (PBM) for health-related quality of life (HRQoL) are essential in assessing the cost-utility of different treatment options. The preference-based Parkinson's disease Index (PB-PDI) is being developed for people with Parkinson's disease (PD). The aim of this study was to refine the PB-PDI through cognitive interviews with people with PD. Cognitive debriefing was conducted to assess patients' interpretation of items, both in English and French. Participants' feedback guided the iterative modification of the PB-PDI and items were accepted for final inclusion if they were endorsed by three consecutive participants. A total of 16 participants provided feedback on the items, refined the response options, and discussed how to clarify questions. They selected a 2-week timeframe for the PB-PDI recall period. At the end of the cognitive interviews, all seven items and their response options were endorsed in both languages. The cognitive interview process allowed us to refine items and ensure that they were clear in terms of instructions and response options from the perspective of people with PD. The next step will be to elicit preference weights to develop a scoring algorithm and assess its measurement properties.

Components of a Behavior Change Model Drive Quality of Life in Community-Dwelling Older Persons

This study aimed to inform a measurement approach for older persons who wish to engage in active living such as participating in a walking program. The Patient Generated Index, an individualized measurement approach, and directed and summative content analyses were carried out. A sample size of 204 participants (mean age 75 years; 62% women) was recruited; it generated 934 text threads mapped to 460 unique categories within 45 domains with similarities and differences for women and men. The Capability, Opportunity, Motivation, and Behaviors Model best linked the domains. The results suggest that older persons identify the need to overcome impaired capacity, low motivation, and barriers to engagement to live actively. These are all areas that active living programs could address. How to measure the outcomes of these programs remains elusive.

Item Selection for a New Health-Related Quality of Life Measure for Parkinson's Disease: The Preference-Based Parkinson's Disease Index (PB-PDI)

Background

Parkinson's disease (PD) is a neurodegenerative condition, predominantly affecting older adults. Preference-based measures (PBMs) can be used to make decisions about the cost-utility of different treatments. There are currently no PBMs for health-related quality of life (HRQoL) for PD. A previous study identified important health domains for individuals with PD and developed an item pool from existing measures per domain. The current study aims to contribute to the development of a new disease-specific PBM of HRQoL for PD by reducing the current pool of items according to the preferences of individuals with PD.

Methods

Fifty-three participants completed a visual analogue scale (VAS) of self-perceived health, the prototype PBM measure, and an item importance rating. To reduce the item pool, the following were calculated: (1) inter-item correlations; (2) impact of each item based on item performance and importance rating; (3) directionality of response options by comparing the VAS scores against each item.

Results

Participants (male = 54.7%, age = 60.0 ± 10.2) had a median Hoehn and Yahr score of 2.5 (interquartile range = 1). Items supported for inclusion by this analysis were sleep, fatigue, tremor, mood, walking, memory, and dexterity. Items demonstrating a logical decrease in VAS score with each increasing severity level were sleep, memory, tremor, fatigue, and mood.

Conclusion

This PBM will be critical for informing decisions about the cost-utility of PD treatments, guiding the resource allocation within our healthcare system. Future research will include cognitive debriefing with individuals with PD to refine item response options.

Development of a Prototype for a Bilingual Patient-Reported Outcome Measure of the Important Health Aspects of Quality of Life in People Living with HIV: The Preference Based HIV Index (PB-HIV)

(1) Background: The aim of this project was to develop a short, HIV-specific, health-related quality of life measure with a scoring system based on patient preferences for the different dimensions of the Preference-Based HIV Index (PB-HIV). (2) Methods: This study is a cross-sectional analysis of data from the Canadian Positive Brain Health Now cohort (n = 854; mean age 53 years). Items from the standardized measures were mapped to the areas from the Patient-Generated Index and formed the domains. A Rasch analysis was used to identify the best performing item to represent each dimension. Each item was then regressed on self-rated health (scored 0 to 100) and the regression parameters were used as scaling weights to form an index score for the prototype measure. (3) Results: Seven independent dimensions with three declarative statements ordered as response options formed the PB-HIV Index (pain, fatigue, memory/concentration, sleep, physical appearance/body image, depression, motivation). Regression parameters from a multivariable model yielded a measure with a scoring range from 0 (worst health) to 100 (perfect health). (4) Conclusions: Preference-based measures are optimal, as the total score reflects gains in some dimensions balanced against losses in others. The PB-HIV Index is the first HIV-specific preference-based measure.

Do Generic Preference-Based Measures Accurately Capture Areas of Health-Related Quality of Life Important to Individuals with Amyotrophic Lateral Sclerosis: A Content Validation Study

Objective

The objectives of this study were to 1) assess the content validity of generic preference-based measures (GPBMs), and (2) examine the convergent validity of the EuroQol 5 Dimension 5 Level (EQ-5D-5L), against the Patient Generated Index (PGI) in Amyotrophic Lateral Sclerosis (ALS).

Methods

Participants were recruited from 3 clinical sites across Canada. The PGI, EQ-5D-5L and Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) were administered through an online or hardcopy survey and scores compared for convergent validation. Domains nominated by participants as important to their health-related quality of life were generated using the PGI, classified using the International Classification of Functioning, Disability and Health (ICF) and mapped onto GPBMs to determine content coverage.

Results

Fifty-two participants (N=28 female; 61.3 ± 11.6 mean age ± standard deviation (SD); 3.5 ± 2.9 mean ± SD years since diagnosis) completed this study. The top three ICF domains identified by participants were recreation and leisure, lower limb mobility, and interpersonal relationships. The Quality of Well-Being Self-Administered (QWB-SA) scale had the highest content coverage (87%) and the Health Utilities Index 3 (HUI3) had the lowest (33%). Two domains were covered by all GPBMs and no GPBM included all domains identified as important by participants. A moderate correlation coefficient of 0.52 between the PGI and EQ-5D-5L was found.

Conclusion

The majority of GPBMs covered only approximately half of the domains important to individuals with ALS suggesting the need for an ALS specific preference-based measure to better reflect the health-related quality of life of this population.

A single patient reported outcome measure for acquired brain injury, multiple sclerosis & Parkinson's disease

OBJECTIVE

To determine psychometric properties of the PROMIS-10 and Standard Stroke Question Set (by International Consortium for Health Outcome Measures) presented as a new 15-item Patient Related Outcome (PRO), for patients with: acquired Brain Injury (ABI), Multiple sclerosis (MS) and Parkinson's disease (PD).

METHODS

In an eight centre, UK wide, cross-sectional study we approached patients during their routine follow-up to complete: a disease-specific instrument (European Brain Injury Questionnaire, Multiple Sclerosis Impact Scale, and Parkinson's disease questionnaire); General Health questionnaire with a Quality of life measure (EQ-5D); and PRO. We validated the PRO using factor analysis to define the latent construct domains, then calculated the internal consistency (Cronbach's-α), and construct validity (correlation).

RESULTS

There were 340 patients with ABI (N = 91, median age = 55.1, 41% female), MS (N = 99, age = 58.9, 69%) and PD (N = 150, age = 74.5, 40%). Factor analysis suggested the PRO offered three domains of: physical health; functionality-capacity and mental health. All factors correlated strongly with the three disease-specific instruments, and the overall PRO had a large correlation with the EQ-5D (correlation>0.8) offering good construct validity and excellent internal consistency (∝>0.89).

INTERPRETATION

The PRO offered promising psychometric properties and could be used in place of disease specific questionnaires for patients with ABI, MS, and PD. The PRO has three construct domains, describing patients': mental health; physical health; and functional-capacity, and may be used in routine clinical practice. The PRO offered both relevance to each of the three separate neurological conditions and generalisability across all the conditions, increasing its utility.

Content validity of preference-based measures for economic evaluation in chronic obstructive pulmonary disease

BACKGROUND

Generic preference-based measures (GPBMs) are health-related quality of life (HRQoL) measures commonly used to evaluate the cost-utility of interventions in healthcare. However, the degree to which the content of GPBMs reflect the HRQoL of individuals with chronic obstructive pulmonary disease (COPD) has not yet been assessed. The purpose of this study was to examine the content and convergent validity of GPBMs in people with COPD.

METHODS

COPD patients were recruited from healthcare centers in Ontario, Canada. The Patient-Generated Index (PGI) (an individualized HRQoL measure) and the RAND-36 (to obtain SF-6D scores; a GPBM) were administered. Life areas nominated with the PGI were coded using the International Classification of Functioning Disability and Health and mapped onto GPBMs.

RESULTS

We included 60 participants with a mean age of 70 and FEV1% predicted of 43. The mean PGI score was 34.55/100 and the top three overarching areas that emerged were: 'mobility' (25.93%), 'recreation and leisure' (25.19%) and 'domestic life' (19.26%). Mapping of the nominated areas revealed that the Quality of Well-Being scale covered the highest number of areas (84.62%), Health Utilities Indices covered the least (15.38% and 30.77%) and other GPBMs covered between 46 and 62%. A correlation of 0.32 was calculated between the SF-6D and the PGI.

CONCLUSIONS

The majority of GPBMs covered approximately half of the areas reported as being important to individuals with COPD. When areas relevant to COPD are not captured, HRQoL scores generated by these measures may inaccurately reflect patients' values and affect cost-effectiveness decisions.

Validation of an Individualized Measure of Quality of Life, Patient Generated Index, for Use with People with Parkinson's Disease

Methods

Patients with PD completed the PGI and various standard patient-reported outcome (PRO) measures. The PGI and standard PRO measures were compared at the total score, domain, and item levels. Pearson's correlations and independent t-tests were used, as well as positive and negative predictive values.

Results

The sample (n = 76) had a mean age of 69 (standard deviation 9) and were predominantly men (59%). The PGI was moderately correlated (r = -0.35) with the standardized disease-specific QOL measure Parkinson's Disease Questionnaire (PDQ-8). Within one severity rating, agreement between the PGI and different standard outcome measures ranged from 85 to 100% for walking, 69 to 100% for fatigue, 38 to 75% for depression, and 20 to 80% for memory/concentration.

Conclusion

This study demonstrates that nominated areas of QOL on the PGI provide comparable results to standard PRO measures, and provides evidence in support of the validity of this individualized measure in PD.