Reliability, validity, and interpretation of the dependence scale in mild to moderately severe Alzheimer's disease

The Costs of Dementia in Europe: An Updated Review and Meta-analysis

BACKGROUND AND OBJECTIVE

The prevalence of dementia is increasing, while new opportunities for diagnosing, treating and possibly preventing Alzheimer's disease and other dementia disorders are placing focus on the need for accurate estimates of costs in dementia. Considerable methodological heterogeneity creates challenges for synthesising the existing literature. This study aimed to estimate the costs for persons with dementia in Europe, disaggregated into cost components and informative patient subgroups.

METHODS

We conducted an updated literature review searching PubMed, Embase and Web of Science for studies published from 2008 to July 2021 reporting empirically based cost estimates for persons with dementia in European countries. We excluded highly selective or otherwise biased reports, and used a random-effects meta-analysis to produce estimates of mean costs of care across five European regions.

RESULTS

Based on 113 studies from 17 European countries, the estimated mean costs for all patients by region were highest in the British Isles (73,712 EUR), followed by the Nordics (43,767 EUR), Southern (35,866 EUR), Western (38,249 EUR), and Eastern Europe and Baltics (7938 EUR). Costs increased with disease severity, and the distribution of costs over informal and formal care followed a North-South gradient with Southern Europe being most reliant on informal care.

CONCLUSIONS

To our knowledge, this study represents the most extensive meta-analysis of the cost for persons with dementia in Europe to date. Though there is considerable heterogeneity across studies, much of this is explained by identifiable factors. Further standardisation of methodology for capturing resource utilisation data may further improve comparability of future studies. The cost estimates presented here may be of value for cost-of-illness studies and economic evaluations of novel diagnostic technologies and therapies for Alzheimer's disease.

Clinical Trajectories at the End of Life in Dementia Patients With Alzheimer Disease and Lewy Body Neuropathologic Changes

BACKGROUND AND OBJECTIVES

Evaluating and understanding the heterogeneity in dementia course has important implications for clinical practice, healthcare decision-making, and research. However, inconsistent findings have been reported with regard to the disease courses of the two most common dementias, Alzheimer's disease (AD) and Dementia with Lewy bodies (DLB). Using autopsy-confirmed diagnoses, we aimed to examine the disease trajectories in the years before death among dementia patients with pure AD, pure DLB, or mixed (AD and DLB) pathologies.

METHODS

The current retrospective longitudinal study included 62 participants with autopsy-confirmed diagnoses of pure AD (n=34), mixed AD and DLB (AD+DLB, n = 17), or pure DLB (n=11) from the Predictors 2 Cohort Study, a prospective, clinic-based, cohort of dementia patients. Generalized estimating equation models, with time zero at death, were used to examine the trajectory of cognition (Folstein Mini-Mental State Examination, MMSE), function (Activities of Daily Living, ADL), and dependence scale among patients with different autopsy-confirmed diagnosis (pure AD, AD+DLB, and pure DLB). The models were adjusted for age, sex, education, and baseline features including extrapyramidal signs, MMSE, ADL, and dependence scale.

RESULTS

The participants on average received 9.4±4.6 assessments at 6-month intervals during a mean 5.4±2.9 years of follow-up time. The three groups were similar in both cognition and function status at baseline. Cognition and function were highly correlated among AD+DLB patients but not in pure AD or pure DLB patients at baseline. Patients of the three groups all declined in both cognition and function but had different trajectories of decline. More specifically, the pure DLB patients experienced approximately double the rate of both cognitive decline and functional decline than the pure AD patients, and the mixed pathology group showed double the rate of functional decline as compared to pure AD patients.

DISCUSSION

In this longitudinal study, we found that among patients with dementia, those with Lewy body pathology experienced faster cognitive and functional decline than those with pure AD pathology.

Dependence Clusters in Alzheimer Disease and Medicare Expenditures: A Longitudinal Analysis From the Predictors Study

INTRODUCTION

Dependence in Alzheimer disease has been proposed as a holistic, transparent, and meaningful representation of disease severity. Modeling clusters in dependence trajectories can help understand changes in disease course and care cost over time.

METHODS

Sample consisted of 199 initially community-living patients with probable Alzheimer disease recruited from 3 academic medical centers in the United States followed for up to 10 years and had ≥2 Dependence Scale recorded. Nonparametric K-means cluster analysis for longitudinal data (KmL) was used to identify dependence clusters. Medicare expenditures data (1999-2010) were compared between clusters.

RESULTS

KmL identified 2 distinct Dependence Scale clusters: (A) high initial dependence, faster decline, and (B) low initial dependence, slower decline. Adjusting for patient characteristics, 6-month Medicare expenditures increased over time with widening between-cluster differences.

DISCUSSION

Dependence captures dementia care costs over time. Better characterization of dependence clusters has significant implications for understanding disease progression, trial design and care planning.

(-)-Phenserine and Inhibiting Pre-Programmed Cell Death: In Pursuit of a Novel Intervention for Alzheimer's Disease

BACKGROUND

Concussion (mild) and other moderate traumatic brain injury (TBI) and Alzheimer's disease (AD) share overlapping neuropathologies, including neuronal pre-programmed cell death (PPCD), and clinical impairments and disabilities. Multiple clinical trials targeting mechanisms based on the Amyloid Hypothesis of AD have so far failed, indicating that it is prudent for new drug developments to also pursue mechanisms independent of the Amyloid Hypothesis. To address these issues, we have proposed the use of an animal model of concussion/TBI as a supplement to AD transgenic mice to provide an indication of an AD drug candidate's potential for preventing PPCD and resulting progression towards dementia in AD.

METHODS

We searched PubMed/Medline and the references of identified articles for background on the neuropathological progression of AD and its implications for drug target identification, for AD clinical trial criteria used to assess disease modification outcomes, for plasma biomarkers associated with AD and concussion/TBI, neuropathologies and especially PPCD, and for methodological critiques of AD and other neuropsychiatric clinical trial methods.

RESULTS

We identified and address seven issues and highlight the Thal-Sano AD 'Time to Onset of Impairment' Design for possible applications in our clinical trials. Diverse and significant pathological cascades and indications of self-induced neuronal PPCD were found in concussion/TBI, anoxia, and AD animal models. To address the dearth of peripheral markers of AD and concussion/TBI brain pathologies and PPCD we evaluated Extracellular Vesicles (EVs) enriched for neuronal origin, including exosomes. In our concussion/TBI, anoxia and AD animal models we found evidence consistent with the presence of time-dependent PPCD and (-)-phenserine suppression of neuronal self-induced PPCD. We hence developed an extended controlled release formulation of (-)-phenserine to provide individualized dosing and stable therapeutic brain concentrations, to pharmacologically interrogate PPCD as a drug development target. To address the identified problems potentially putting any clinical trial at risk of failure, we developed exploratory AD and concussion/TBI clinical trial designs.

CONCLUSIONS

Our findings inform the biomarker indication of progression of pathological targets in neurodegenerations and propose a novel approach to these conditions through neuronal protection against self-induced PPCD.

Dependence Levels as Interim Clinical Milestones Along the Continuum of Alzheimer's Disease: 18-Month Results from the GERAS Observational Study

BACKGROUND

While functional loss forms part of the current diagnostic criteria used to identify dementia due to Alzheimer's disease, the gradual and progressive nature of the disease makes it difficult to recognize clinically relevant signposts that could be helpful in making treatment and management decisions. Having previously observed a significant relationship between stages of functional dependence (the level of assistance patients require consequent to Alzheimer's disease deficits, derived from the Alzheimer's Disease Cooperative Study - Activities of Daily Living Scale) and cognitive severity, we investigated whether measures of functional dependence could be utilized to identify clinical milestones of Alzheimer's disease progression.

OBJECTIVES

To describe the patterns of change in dependence over the course of 18 months in groups stratified according to cognitive Alzheimer's disease dementia severity (determined using the Mini-Mental State Examination score) and to identify characteristics associated with patients showing worsening dependence (progressors) versus those showing no change or improvement (non-progressors).

DESIGN

Analysis of longitudinal data from the GERAS study.

SETTING

GERAS is an 18-month prospective, multicenter, naturalistic, observational cohort study reflecting the routine care of patients with Alzheimer's disease in France, Germany, and the United Kingdom.

PARTICIPANTS

1495 community-living patients, aged ≥55 years, diagnosed with probable Alzheimer's disease dementia, and their caregivers.

MEASUREMENTS

Dependence levels, cognitive function, behavioral symptoms, caregiver burden, and cost were assessed at baseline and at 18 months.

RESULTS

Of 971 patients having both baseline and 18-month data, 42% (408) were progressors and 563 (58%) were non-progressors. This general pattern held for all three levels of baseline Alzheimer's disease dementia severity - mild (Mini-Mental State Examination score 21-26), moderate (15-20) or moderately severe/severe (<15) - with 40-45% of each group identified as progressors and 55-60% as non-progressors. No baseline differences were seen between progressors and non-progressors in cognitive scores or behavioral symptoms, although progressors had significantly shorter times since diagnosis and showed milder functional impairment. Baseline factors predictive of increasing dependence over 18 months included more severe cognitive impairment, living with others, and having multiple caregivers. A higher level of initial dependence was associated with less risk of dependence progression. Total societal costs of care also increased with greater dependence.

CONCLUSIONS

In this large cohort, 42% of Alzheimer's disease dementia patients at all levels of cognitive severity became more dependent within 18 months of observation while 58% did not progress. Dependence levels may be considered as meaningful interim clinical milestones that reflect Alzheimer's disease-related functional deficits, although a time frame that extends beyond 18 months may be necessary to observe changes if used in clinical trials or other longitudinal studies. Recognition of predictors of greater dependence offers opportunities for intervention.

Utility of the Dependence Scale in dementia: validity, meaningfulness, and health economic considerations

Background

The concept of dependence has been proposed as a unified representation of disease severity to quantify and stage disease progression in a manner more informative to patients, caregivers, and healthcare providers.

Methods

This paper provides a review of the Dependence Scale (DS) as a quantitative measure of Alzheimer’s disease severity, its properties as an outcome measure, a metric of disease progression, and a correlate of medical costs.

Results

The literature supports the notion that the DS is related to, but distinct from, key severity measures, including cognition, function, and behavior, and captures the full spectrum of patient needs. It also presents as a useful measure for assessing disease progression.

Conclusions

Results underscore the importance of the DS as a unique endpoint in Alzheimer’s disease clinical trials, providing important information about the impact of therapeutic interventions. The DS also is a useful measure for economic evaluation of novel interventions aimed at delaying progression.

Assessing Dependency in a Multiethnic Community Cohort of Individuals With Alzheimer's Disease

BACKGROUND AND OBJECTIVES

Clinic-based studies of patients with Alzheimer's disease (AD) have demonstrated the value of assessing dependence when characterizing patients' functional status. The Dependence Scale, a validated tool to assess level of caregiving needs, is associated with markers of disease severity, cost, and progression, while offering independent functional information about patients. This study examines whether such associations between the Dependence Scale and markers of disease severity demonstrated in clinical cohorts are similarly exhibited in a multiethnic community population of individuals with AD.

RESEARCH DESIGN AND METHODS

One hundred fifty four elders with AD enrolled in the Predictors 3 cohort were assessed with the Dependence Scale, modified Mini-Mental State Examination (mMMS), instrumental (IADL) and basic (BADL) activities of daily living, and Clinical Dementia Rating (CDR) Scale, and were assigned an Equivalent Institutional Care (EIC) rating. Cross-sectional associations were examined using bivariate correlations and one-way analysis of variance analyses. Fisher-z tests examined differences in strengths of associations across previous clinic and current community cohorts.

RESULTS

Dependence Scale scores were associated with CDR (r = .20, p = .013), mMMS (r = -.23, p = .005), IADL (r = .39, p < .001), BADL (r = .65, p < .001), and EIC (r = .51, p < .001). Dependence was unassociated with ethnicity (F[3,144] = 1.027, p = .3822), age (r = .120, p = .145), and education (r = -.053, p = .519). The strength of the correlations was comparable across cohorts except that BADLs were more strongly associated with dependence (z = -4.60, p < .001) in the community cohort, and living arrangement was not associated with dependence (r = .13, p = .130).

DISCUSSION AND IMPLICATIONS

Associations between the Dependence Scale and markers of disease severity in a clinic-based cohort of AD patients are similar to associations in a multiethnic community cohort of individuals diagnosed with AD. The Dependence Scale relates to markers of disease severity rather than demographic factors, and may offer an unbiased assessment of care required in multiethnic and community populations.

Effects of Spiritual Group Therapy on Caregiver Strain in Home Caregivers of the Elderly with Alzheimer's Disease

INTRODUCTION

Care of patients with Alzheimer's disease is one of the most difficult types of care that exposes the caregiver to a high level of care strain. The present research aimed at determining the effect of spiritual care on caregiver strain of the elderly with Alzheimer's disease.

METHODS

An experimental study was carried out on 100 caregivers who were selected by convenience sampling and randomly divided into intervention, control one and control two groups. Group spiritual therapy was performed on the intervention group for five weeks, Control one participate in the group sessions without any particular interventions, and control two received no interventions. Data was collected through a demographic questionnaire and Robinson's (1983) Caregiver Strain Index, and analyzed using the Chi-square, Fisher's Exact test, one-way analysis of variance and paired t-test. Statistical significance level was considered as 0.05.

RESULTS

In the intervention group mean of the posttest care strain score 32.43±2.73 was significantly lower than pretest 37.16±1.26 (P<0.001). The mean posttest score of care strain was significantly lower in the intervention group compared to the two other groups (P<0.001).

CONCLUSION

Spiritual care can reduce care strain in home caregivers of the elderly with Alzheimer's disease.

Dependence Stage and Pharmacoeconomic Outcomes in Patients With Alzheimer Disease

The level of assistance patients with Alzheimer disease (AD) require in their care may be an important predictor of resource use, costs of care, and quality of life. The Dependence Scale (DS), a measure of care-assistance required, was used to estimate costs of care and quality of life of patients with AD categorized into 6 dependence stages based upon the summated item scores of the DS. Data were derived from a 3-year, noninterventional study of 132 patients with probable AD (ages, 50 to 85 y) and caregiver dyads. We investigated the association between DS scores and health care costs, health-related quality of life (HRQoL), caregiver burden and estimated annual costs and HRQoL for 6 dependence stages in adjusted models. DS scores were significant predictors of health care costs, HRQoL, and caregiver burden. The estimated annual health care costs and a measure of HRQoL (EuroQoL-5D) ranged from $11,418 and 1.00 for those at very mild dependence stage to $101,715 and 0.26 for those at very severe dependence stage. DS scores classified into 6 dependence stages provides a useful method to estimate unique levels of care-associated costs and health utilities for pharmacoeconomic evaluations of new treatments for AD.

A Path Analysis of Dependence and Quality of Life in Alzheimer's Disease

OBJECTIVE

To determine the direct and indirect relationships of cognitive, functional, and behavioral factors and other medical comorbidities with the quality of life (QoL) of patients with Alzheimer's disease (AD) according to the theoretical model of dependence.

METHODS

Observational and cross-sectional study. Cognitive and functional status, behavior, dependence, medical comorbidities, and QoL were assessed by using standardized instruments. A path analysis was used to model the direct and indirect relationships among clinical indicators according to the theoretically based model of dependence.

RESULTS

The sample consisted of 343 patients with AD (32.1% mild, 36.7% moderate, and 31.2% severe). Medical comorbidities, disease severity, and dependence level had a direct relationship with QoL. The functional disability and the behavior disturbances were indirectly related to QoL via dependence level, and the cognitive impairment was indirectly related to QoL via severity level.

CONCLUSION

Direct and indirect effects exist between clinical indicators, dependence, and QoL.

Clinical and Economic Characteristics of Milestones along the Continuum of Alzheimer's Disease: Transforming Functional Scores into Levels of Dependence

BACKGROUND

Because Alzheimer's disease (AD) is characterized by a gradual decline, it can be difficult to identify distinct clinical milestones that signal disease advancement. Adapting a functional scale may be a useful way of staging disease progression that is more informative for healthcare systems.

OBJECTIVES

To adapt functional scale scores into discrete levels of dependence as a way of staging disease progression that is more informative to care providers and stakeholders who rely on the functional impact of diseases to determine access to supportive services and interventions.

DESIGN

Analysis of data from the GERAS study.

SETTING

GERAS is an 18-month prospective, multicenter, naturalistic, observational cohort study reflecting the routine care of patients with AD in France, Germany, and the United Kingdom.

PARTICIPANTS

Data were from baseline results of 1497 community-living patients, aged ≥55 years, diagnosed with probable AD and their caregivers.

MEASUREMENTS

We used data from the Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory (ADCS-ADL) and mapped items onto established categories of functional dependence, validated using clinical and economic measures. Cognitive function, behavioral symptoms, caregiver burden, and cost were assessed. Based on stages of functional dependence described by the Dependence Scale, individual ADCS-ADL items were used to approximate 6 dependence levels.

RESULTS

There was a significant relationship between assigned level of dependence derived from the ADCS-ADL score and cognitive severity category. As the assigned level of dependence increased, the associated clinical and economic indicators demonstrated a pattern of greater disease severity.

CONCLUSIONS

This mapping provides initial support for dependence levels as appropriate interim clinical milestones that characterize the functional deficits associated with AD.

Psychometric properties of the Dependence Scale in large randomized clinical trials of patients with mild and moderate Alzheimer's disease

OBJECTIVE

The need for assistance from others is a hallmark concern in Alzheimer's disease (AD). The psychometric properties of the Dependence Scale (DS) for measuring treatment benefit were investigated in large randomized clinical trials of patients with mild to moderate AD.

METHODS

Reliability, validity, and responsiveness of the DS were examined. Path models appraised relationships and distinctiveness of key AD measures. The responder definition was empirically derived.

RESULTS

Generally acceptable reliability (α ≥ .65), significant (P < .001) known-groups tests, and moderate to strong correlations (r ≥ .31) confirmed the DS psychometric properties. Path models supported relationships and distinctiveness of key AD measures. A DS change of ≤ 1 point for patients with limited home care and ≤ 2 points for patients with assisted living care best described stability of the level of dependence on caregivers.

CONCLUSION

The DS is a psychometrically robust measure in mild to moderate AD. The empirically derived responder definition aids in the interpretation of DS change.

Evaluating disease-modifying agents: a simulation framework for Alzheimer's disease

BACKGROUND

Considerable advances have been made in modeling Alzheimer's disease (AD), with a move towards individual-level rather than cohort models and simulations that consider multiple dimensions when evaluating disease severity. However, the possibility that disease-modifying agents (DMAs) may emerge requires an update of existing modeling frameworks.

OBJECTIVES

The aim of this study was to develop a simulation allowing for economic evaluation of DMAs in AD.

METHODS

The model was developed based on a previously published, well-validated, discrete event simulation which measures disease severity on the basis of cognition, behaviour, and function, and captures the interrelated changes in these measures for individuals. The updated model adds one more domain, patient dependence, in addition to cognition, behaviour, and function to better characterize disease severity. Furthermore, the model was modified to have greater flexibility in assessing the impact of various important assumptions, such as the long-term effectiveness of DMAs and their impact on survival, on model outcomes. A validation analysis was performed to examine how well the model predicted change in disease severity among patients not receiving DMA treatment by comparing model results to those observed in two recent phase III clinical trials of bapineuzumab. In addition, various hypothetical scenarios were tested to demonstrate the improved features of the model.

RESULTS

Validation results show that the model closely predicts the mean changes in disease severity over 18 months. Results from different hypothetical scenarios show that the model allows for credible assessment of those major uncertainties surrounding the long-term effectiveness of DMAs, including the potential impact of improved survival with DMA treatment. They also indicate that varying these assumptions could have a major impact on the value of DMAs.

CONCLUSIONS

The updated economic model has good predictive power, but validation against longer-term outcomes is still needed. Our analyses also demonstrate the importance of designing a model with sufficient flexibility such that the model allows for assessment of the impact of key sources of uncertainty on the value of DMAs.