Huntington's Disease and Employment: The Relative Contributions of Cognitive and Motor Decline to the Decision to Leave Work

Health state utility estimates for value assessments of novel treatments in Huntington's disease: a systematic literature review

BACKGROUND

Huntington's disease (HD) is a progressive neurodegenerative disease with a devastating impact on patients and their families. Quantifying how treatments affect patient outcomes is critical for informing reimbursement decisions. Many countries mandate a formal value assessment in which the treatment benefit is measured as quality-adjusted life-years, calculated with the use of utility estimates that reflect respondents' preferences for health states.

OBJECTIVE

To summarize published health state utility data in HD and identify gaps and uncertainties in the data available that could be used to inform value assessments.

METHODS

We conducted a systematic literature review of studies that used preference-based instruments (e.g., EQ-5D and SF-6D) to estimate utility values for people with HD. The studies were published between January 2012 and December 2022.

RESULTS

Of 383 articles screened, 16 articles reported utility values estimated in 11 distinct studies. The utility measure most frequently reported was EQ-5D (9/11 studies). Two studies reported SF-6D data; one used time trade-off methods to value health state descriptions (vignettes). Although utility scores generally worsened to a lower value with increased HD severity, the estimates varied considerably across studies. The EQ-5D index range was 0.89 - 0.72 for mild/prodromal HD and 0.71 - 0.37 for severe/late-stage disease.

CONCLUSIONS

This study uncovered high variability in published utility estimates, indicating substantial uncertainty in existing data. Further research is needed to better understand preferences and valuation across all stages and domains of HD symptoms and the degree to which generic utility measures capture the impact of cognitive changes on quality of life.

Prevalence of neurocognitive disorder in Huntington's disease using the Enroll-HD dataset

Background

Cognitive decline in Huntington's disease (HD) begins early in the disease course, however the reported prevalence and severity of cognitive impairment varies based on diagnostic approach. A Movement Disorders Society Task Force recently endorsed the use of standardized DSM-5-based criteria to diagnose neurocognitive disorder (NCD) in Huntington's disease.

Objectives

To determine the prevalence and severity of cognitive impairment across different stages of HD by applying NCD criteria (mild and major) to participant data from the Enroll-HD database.

Methods

Enroll-HD participants were triaged into either premanifest (preHD), manifest or control groups. PreHD was further dichotomized into preHD near or preHD far based on predicted time to diagnosis using the scaled CAG-age product score (CAPs). Embedded cognitive performance and functional independence measures were used to determine prevalence of NCD (mild and major) for all groups.

Results

Prevalence of NCD-mild was 25.2%-38.4% for manifest HD, 22.8%-47.3% for preHD near, 11.5%-25.1% for preHD far, and 8.8%-19.1% for controls. Prevalence of NCD-major was 21.1%-57.7% for manifest HD, 0.5%-16.3% for preHD near, 0.0%-4.5% for preHD far, and 0.0%-3.0% for controls.

Conclusion

The prevalence of NCD in HD is elevated in preHD and demonstrates a sharp rise prior to diagnosis. In manifest HD, the vast majority of participants meet criteria for NCD. These findings are important for optimizing clinical care and/or anticipating the need for supportive services.

Disease Burden of Huntington's Disease (HD) on People Living with HD and Care Partners in Canada

Background:

Huntington’s disease (HD) has been shown to reduce health-related quality of life (HRQoL) and affect healthcare resource utilization (HRU) among patients and care partners internationally but has not been studied specifically in the Canadian context.

Objective:

To characterize the burden of HD on individuals with HD and care partners of individuals with HD in Canada.

Methods:

An online survey was distributed (September 14–November 23, 2020) through patient organizations to collect data on demographic and clinical characteristics, as well as: HRQoL, measured using the 36-Item Short-Form Health Survey (SF-36v1); HRU, measured using the Client Service Receipt Inventory (CSRI); and care partner burden, measured using the Caregiver Strain Index (CSI) and Huntington’s Disease Quality of Life Battery for Carers (HDQoL-C). Descriptive statistics were used to report data and compare subgroups.

Results:

A total of 62 adult individuals with HD (or their proxies) and 48 care partners met defined eligibility criteria. The mean [standard deviation] age was 51.2 [13.8] and 58.1 [13.9] years for individuals with HD and care partner respondents, respectively. For individuals with HD, the greatest HRQoL burden (i.e., lowest score) was for the SF-36v1 Role –Physical scale (46.8 [42.9]). HRU was higher for some services (e.g., general practitioner visits) for respondents who had experienced motor onset transition. Among care partners, 55.3% experienced high strain, as indicated by the CSI. The HDQoL-C showed the greatest HRQoL burden in feelings about life (45.1 [17.9]).

Conclusion:

This study quantified the substantial burden on individuals with HD and care partners in Canada, addressing a critical knowledge gap that can affect the availability of and access to healthcare services.

Huntington's disease influences employment before and during clinical manifestation: A systematic review

Huntington's disease (HD) is an inherited neurodegenerative disease. People at risk for HD can choose to get predictive testing years before the clinical onset. HD is characterized by motor, cognitive and psychiatric symptoms and has a mean age at onset between 30 and 50 years, an age at which people are usually still working. This systematic review focuses on summarizing which disease-specific characteristics influence employment and working capacity in HD. Twenty-three studies were identified and showed that while employment and working capacity in HD are negatively influenced by cognitive decline and motor impairments, apathy already plays a role in the prodromal stage. Moreover, the influence of HD transcends the clinical manifestation of the disease, as some people at risk are already experiencing the impact of HD on employment through fear of or actual genetic discrimination. Employment and working capacity are not influenced by predictive testing for HD in and of itself.

A Machine-Learning Derived Huntington's Disease Progression Model: Insights for Clinical Trial Design

BACKGROUND

Applying machine-learning algorithms to large datasets such as those available in Huntington's disease offers the opportunity to discover hidden patterns, often not discernible to clinical observation.

OBJECTIVES

To develop and validate a model of Huntington's disease progression using probabilistic machine learning methods.

METHODS

Longitudinal data encompassing 2079 assessment measures from four observational studies (PREDICT-HD, REGISTRY, TRACK-HD, and Enroll-HD) were integrated and machine-learning methods (Bayesian latent-variable analysis and continuous-time hidden Markov models) were applied to develop a probabilistic model of disease progression. The model was validated using a separate Enroll-HD dataset and compared with existing clinical reference assessments (Unified Huntington's Disease Rating Scale [UHDRS] diagnostic confidence level, total functional capacity, and total motor scores) and CAG-age product.

RESULTS

Nine disease states were discovered based on 44 motor, cognitive, and functional measures, which correlated with reference assessments. The validation set included 3158 participants (mean age, 48.4 years) of whom 61.5% had manifest disease. Analysis of transition times showed that "early-disease" states 1 and 2, which occur before motor diagnosis, lasted ~16 years. Increasing numbers of participants had motor onset during "transition" states 3 to 5, which collectively lasted ~10 years, and the "late-disease" states 6 to 9 also lasted ~10 years. The annual probability of conversion from one of the nine identified disease states to the next ranged from 5% to 27%.

CONCLUSIONS

The natural history of Huntington's disease can be described by nine disease states of increasing severity. The ability to derive characteristics of disease states and probabilities for progression through these states will improve trial design and participant selection. © 2021 International Parkinson and Movement Disorder Society.

Predictors of Working Capacity Changes Related to Huntington's Disease: A Longitudinal Study

BACKGROUND

Huntington's disease (HD) is an inherited neurodegenerative disorder that is characterized by motor, cognitive, and psychiatric symptoms. Although 65%of HD expanded gene carriers report changes in employment as the first functional loss, little is known about the predictors leading to changes of working capacity. Given the impact on quality of life, understanding of these factors is of great clinical value.

OBJECTIVE

This study evaluates disease specific characteristics and their predictive value in loss of working capacity in HD.

METHODS

Longitudinal data was collected through the worldwide observational study (Enroll-HD), with 15,301 participants in total and 2,791 HD and healthy control participants meeting the inclusion criteria. Changes in working capacity were analyzed by means of a survival analysis. Predictive values of demographic factors and clinical characteristics were assessed for premanifest and manifest HD through Cox regressions.

RESULTS

HD expanded gene carriers, manifest and premanifest combined, had a 31%chance of experiencing changes in employment after three years, compared to 4%in healthy controls. Apathy was found to be the most crucial determinant of working capacity changes in premanifest HD, while executive and motor dysfunction play an important role in manifest HD.

CONCLUSION

HD expanded gene carriers are more likely to lose working capacity compared to healthy controls. Disease progression, altered motor function, cognitive decline, and in an early stage of the disease apathetic symptoms are indicative of negative changes in working capacity. Clinicians should recognize that early disease related changes, especially apathy, can affect working capacity.

Influence of Age of Onset on Huntington's Disease Phenotype

Background

Older patients with Huntington's disease (HD) are often thought to have a slower progressing disease course with less behavioral symptoms than younger patients. However, phenotypic differences based on age of onset have not been well characterized in a large HD population. This study will determine the difference in manifestations and disease progression between patients with young, typical, and late onset adult HD at different stages of disease.

Methods

Data obtained from Enroll-HD. Adults with manifest HD were included. Age groups were defined as young onset (YO: 20-29 years), typical onset (TO: 30-59 years), and late onset (LO: 60+ years). Subjects were categorized by TFC score, from Stage I (least severe) to Stage V (most severe). Motor, cognitive, and behavioral symptoms were analyzed. Descriptive statistics and Bonferroni p-value correction for pairwise comparison were calculated.

Results

7,311 manifest HD participants were included (612 YO, 5,776 TO, and 923 LO). The average decline in TFC score from baseline to second visit (1.5-2.5 years) was significantly faster for YO (-1.75 points) compared to TO (-1.23 points, p = 0.0105) or LO (-0.97 points, p = 0.0017). Motor deficits were worse for LO participants at early stages of HD, and worse for YO participants at advanced stages. YO and TO participants had greater burden of behavioral symptoms at early stages of disease compared to LO.

Discussion

YO is predictive of a faster functional decline for adults with HD when compared to those with TO and LO. Motor and behavioral manifestations differ based on age of onset.

Highlights

This study compares HD manifestations while controlling for disease severity, detailing robust phenotypic differences by age of onset alone. These findings have implications for the clinical management of HD symptoms and have the possibility to improve prognostic and treatment precision.

Keeping People with Dementia or Mild Cognitive Impairment in Employment: A Literature Review on Its Determinants

Background: Approximately 10–20% of people with early onset dementias (EOD) or mild cognitive impairment (MCI) are aged under 65 and, due to extended working life and increasing prevalence of dementias, they more and more frequently will be present in the active workforce. This review aimed to synthesize the available information about the ability of people with EOD or MCI to retain their participation in the labor workforce. Methods: We searched SCOPUS and EMBASE for peer-reviewed papers that reported studies assessing work ability in employees with EOD or MCI that were published in the period of January 2010 to August 2019. Results: We selected four publications, in which 1012 participants with EOD or MCI were enrolled (41.2% males). Cognitive difficulties rather than motor dysfunction were found to reduce patients’ ability to work. Two main themes emerged: management of dementia in the workplace and the impact of symptoms on working status. Conclusions: EOD and MCI impact on workforce participation by determining problems in executive functions. Although this review was based on a small sample of studies, it can be shown that support in the workplace may act as a facilitator to enhance workforce participation, and occupational health professionals can help patients with EOD or MCI continue working as much as possible.

Therapeutic Use of Music, Dance, and Rhythmic Auditory Cueing for Patients with Huntington's Disease: A Systematic Review

Background:

Studies have assessed the therapeutic effect of music, dance, and rhythmic auditory cueing for patients with Huntington’s disease (HD). However, the synthesis of evidence in support of their positive impact on symptoms is lacking.

Objective:

We conducted a systematic literature review to evaluate the potential benefits of music, dance, and rhythm on the cognitive, psychiatric and motor function in patients with HD.

Methods:

Two- and three-keyword searches and a manual search identified medical literature published from 1999 through 2019. We considered literature that assessed outcomes of art-based rehabilitation programs or individual modalities for persons with early, middle, or advanced HD. Structured analysis was conducted using data entry tables with categories for patient health status, art methods, and outcomes.

Results:

Seven articles and six abstracts met eligibility criteria, of which nine evaluated art-based rehabilitation programs. Studies mainly assessed cognitive, psychiatric, and motor functions through music, dance, or rhythm modalities. Although results were conflicting, in summary improvements to motor function were dependent on disease severity and more responsive to art therapy programs than rhythm-motor synchronization. Benefits to global cognition that resulted from rhythmic training correlated with microstructural changes. Qualitative data verified a positive impact on language production, chorea, behavior, and quality of life.

Conclusions:

Our review has shown a potential benefit of music, dance, and rhythm for patients with HD, which is particularly important for a disease that has no cure. Art forms seemed to affect cognitive, psychiatric, motor, psychosocial, and neuroanatomical domains. However, evidence is preliminary, warranting further investigation to establish the foundation for this field.