Quality of Life and Utility Measurement in a Large Clinical Trial Sample of Patients with Mild to Moderate Alzheimer's Disease: Determinants and Level of Changes Observed

OBJECTIVE

To evaluate the performance (in terms of responsiveness to change, associations with other criterion standards, and indicators of Alzheimer's disease [AD] severity) of a quality-of-life measure (Quality of Life in Alzheimer's Disease [QOL-AD]) and a health utility measure (Health Utilities Index Mark 3 [HUI-3]) from two recently completed clinical trials of a new drug for AD.

METHODS

Change from baseline scores was calculated, and treatment effects were analyzed using mixed models for repeated measures. Three separate models were then estimated to examine the association between the quality-of-life/utility end points and the clinical and other health outcome end points measured during the trials, including cognition, function, behavior, and dependence.

RESULTS

The performance of the two measures differed. Subject-assessed QOL-AD was found to be weakly associated with clinical measures of cognition, and with caregiver reports of function, behavior, and dependence, and showed little movement over time and did not appear to differ by baseline AD severity. Proxy-assessed QOL-AD scores were consistently lower than subject-assessed scores, and the level of decline in QOL-AD was greater using proxy-assessed QOL-AD. Proxy-assessed HUI-3 scores were more strongly associated with clinical measures of cognition, function, behavior, and dependence than the subject- and proxy-assessed QOL-AD scores. Larger proportionate changes over 78 weeks were observed with HUI-3 scores and greater separation in HUI-3 scores by baseline severity.

CONCLUSIONS

Subject-assessed QOL-AD is less likely than proxy-assessed QOL-AD to respond to changes in clinical measures used to track progression in clinical trials of subjects with mild to moderate AD. Proxy-assessed HUI-3 assessments were more in line with other outcome assessments and could therefore be better outcome measures to evaluate clinical progression in mild to moderate AD.

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

INTRODUCTION

The Dependence Scale (DS) was designed to measure dependence on others among patients with Alzheimer's disease (AD). The objectives of this research were primarily to strengthen the psychometric evidence for the use of the DS in AD studies.

METHODS

Patients with mild to moderately severe AD were examined in 3 study databases. Within each data set, internal consistency, validity, and responsiveness were examined, and structural equation models were fit.

RESULTS

The DS has strong psychometric properties. The DS scores differed significantly across known groups and demonstrated moderate to strong correlations with measures hypothesized to be related to dependence (|r| ≥ .31). Structural equation modeling supported the validity of the DS concept. An anchor-based DS responder definition to interpret a treatment benefit over time was identified.

DISCUSSION

The DS is a reliable, valid, and interpretable measure of dependence associated with AD and is shown to be related to--but provides information distinct from--cognition, functioning, and behavior.

Association between illness progression measures and total cost in Alzheimer's disease

OBJECTIVE

To compare the associations between dependence and clinical measures of cognition, function and behaviour and total care cost using data from a longitudinal study in Alzheimer's disease (AD).

DESIGN

Longitudinal, observational study.

SETTING

Community-dwelling subjects.

PARTICIPANTS

Male and female subjects between 50 and 85 years of age with mild to moderate AD.

INTERVENTION

None.

MEASUREMENTS

Subject dependence was assessed using the Dependence Scale (DS), cognition (ADAS-Cog, MMSE), function (DAD), behaviour (NPI) and resource utilization with the Resource Utilization in Dementia Questionnaire.

RESULTS

The repeated measures models confirmed a significant association between the DS and total care cost indicating an increase in cost with increasing dependence. A 1-unit increase in DS score was associated with a 28.60% increase in total care cost. Model 2 indicated that a one point change in MMSE, DAD and NPI is associated with 5.29%, 2.32% and 1.71% increase in total cost, respectively. Model 3 indicated that a one point change in ADAS-Cog, DAD and NPI is associated with a 1.74%, 2.42%and 1.62% increase in total cost, respectively.

CONCLUSION

Strategies which prevent deterioration in clinical measures or delay dependence should result in total cost savings. The quantitative relationships observed should assist in the economic assessment of interventions which effect cognition, function, behaviour and dependence.

Staging dementia from symptom profiles on a care partner website

BACKGROUND

The World Wide Web allows access to patient/care partner perspectives on the lived experience of dementia. We were interested in how symptoms that care partners target for tracking relate to dementia stage, and whether dementia could be staged using only these online profiles of targeted symptoms.

OBJECTIVES

To use clinical data where the dementia stage is known to develop a model that classifies an individual's stage of dementia based on their symptom profile and to apply this model to classify dementia stages for subjects from a Web-based dataset.

METHODS

An Artificial Neural Network (ANN) was used to identify the relationships between the dementia stages and individualized profiles of people with dementia obtained from the 60-item SymptomGuide (SG). The clinic-based training dataset (n=320), with known dementia stages, was used to create an ANN model for classifying stages in Web-based users (n=1930).

RESULTS

The ANN model was trained in 66% of the 320 Memory Clinic patients, with the remaining 34% used to test its accuracy in classification. Training and testing staging distributions were not significantly different. In the 1930 Web-based profiles, 309 people (16%) were classified as having mild cognitive impairment, 36% as mild dementia, 29% as moderate, and 19% as severe. In both the clinical and Web-based symptom profiles, most symptoms became more common as the stage of dementia worsened (eg, mean 5.6 SD 5.9 symptoms in the MCI group versus 11.9 SD 11.3 in the severe). Overall, Web profiles recorded more symptoms (mean 7.1 SD 8.0) than did clinic ones (mean 5.5 SD 1.8). Even so, symptom profiles were relatively similar between the Web-based and clinical datasets.

CONCLUSION

Symptoms targeted for online tracking by care partners of people with dementia can be used to stage dementia. Even so, caution is needed to assure the validity of data collected online as the current staging algorithm should be seen as an initial step.

Validation of an informant-reported web-based data collection to assess dementia symptoms

Background

The Web offers unprecedented access to the experience of people with dementia and their care partners, but data gathered online need to be validated to be useful.

Objective

To test the construct validity of an informant Web-based data collection to assess dementia symptoms in relation to the 15-point Dependence Scale (DS).

Methods

In an online survey posted on the DementiaGuide website, care partners of people with dementia built individualized profiles from the 60-item SymptomGuide and completed a questionnaire, which included the DS and a staging tool.

Results

In the 250 profilees (155, 62% women, mean age 77 years), increasing dependence was associated with a greater chance of institutionalization. For example, no one at the lowest levels of dependence (DS score < 5, n = 33) was in long-term care, compared with half (13/25) of the profilees at the highest levels of dependence (DS score > 12) being in institutions (χ²₄ = 27.9, P < .001). The Web-based DS was correlated with the number of symptoms: higher DS scores were associated with a higher stage of dementia (F > 50, P < .001).

Conclusion

In an online survey, the Web-based DS showed good construct validity, potentially demonstrating how the Web can be used to learn more about dementia progression and how it relates to symptoms experienced by patients across the course of dementing illnesses. Even so, caution is needed to assure the validity of data collected online.

Assessment of potential measures in models of progression in Alzheimer disease

BACKGROUND

In estimating the potential benefits of treatment, it is often necessary to extrapolate beyond clinical trial results using economic modeling. Previous attempts in Alzheimer disease (AD) were primarily based on the Mini-Mental State Examination (MMSE) due to its widespread use. These models were criticized as not accurately reflecting the total impact of the disease, providing untrustworthy estimates of treatment benefit. We compared 3 alternatives to the MMSE with respect to bridging between clinical outcomes needed for regulatory approval and economic and quality of life (QOL) outcomes important to reimbursement agencies.

METHODS

The MMSE, Disability Assessment in Dementia (DAD) scale, Clinical Dementia Rating (CDR) scale, and Dependence Scale (DS) were compared in their ability to explain variation in cognitive, functional, and behavioral measures as well as economic and QOL outcomes using univariate (Pearson correlations) and multivariate (linear regression) analyses of data from research sites in the United States and Europe.

RESULTS

Subjects with mild to moderate AD (n = 196; mean 75.9 years; 56% female) were evaluated. The DS, DAD, and CDR were moderately correlated with the MMSE (Pearson correlations, range 0.54-0.58) but performed better (higher adjusted R(2)) than the MMSE in explaining variations in subject behavior, QOL, and health status. The DS and DAD performed better in explaining variation in medical costs, caregiver QOL, and caregiver time.

CONCLUSIONS

Measures of function (DAD) or dependence on others (DS), or global measures (CDR), appear to be better candidates than the MMSE for modeling AD progression.

Novel approaches to incorporating pharmacoeconomic studies into phase III clinical trials for Alzheimer's disease

The societal and individual costs of Alzheimer's disease are significant, worldwide. As the world ages, these costs are increasing rapidly, while health systems face finite budgets. As a result, many regulators and payers will require or at least consider phase III cost-effectiveness data (in addition to safety and efficacy data) for drug approval and reimbursement, increasing the risks and costs of drug development. Incorporating pharmacoeconomic studies in phase III clinical trials for Alzheimer's disease presents a number of challenges. We propose several specific suggestions to improve the design of pharmacoeconomic studies in phase III clinical trials. We propose that acute episodes of care are key outcome measures for pharmacoeconomic studies. To improve the possibility of detecting a pharmacoeconomic impact in phase III, we suggest several strategies including; study designs for enrichment of pharmacoeconomic outcomes that include co-morbidity of patients; reducing variability of care that can affect pharmacoeconomic outcomes through standardized care management; employing administrative claims data to better capture meaningful pharmacoeconomic data; and extending clinical trials in open label follow-up periods in which pharmacoeconomic data are captured electronically by administrative claims. Specific aspects of power analysis for pharmacoeconomic studies are presented. The particular pharmacoeconomic challenges caused by the use of biomarkers in clinical trials, the increasing use of multinational studies, and the pharmacoeconomic challenges presented by biologicals in development for Alzheimer's disease are discussed. In summary, since we are entering an era in which pharmacoeconomic studies will be essential in drug development for supporting regulatory approval, payor reimbursement and integration of new therapies into clinical care, we must consider the design and incorporation of pharmacoeconomic studies in phase III clinical trials more seriously and more creatively.

A qualitative assessment of the concept of dependence in Alzheimer's disease

BACKGROUND

The Dependence Scale (DS) was designed to assess levels of patient need for care due to deficits typical of Alzheimer's disease (AD). This study examined content validity of the DS based on input from patients, caregivers, and clinicians.

METHODS

Qualitative interviews with experts, patients, and caregivers were used to collect information on the concept of dependence and to assess content validity.

RESULTS

Nine clinicians rated item relevance ''high'' with consensus on the primacy of functional abilities and dependence in the measurement of AD progression. Twenty-two US, 11 UK, and 14 informal caregivers from Spain participated in focus groups; 18 patients participated in 3 separate focus groups. Discussion supported DS hierarchy of dependence, capture of mild-to-severe dependence, suitability of response options, and short recall time frame.

CONCLUSIONS

Clinicians, caregivers, and patients support content validity of the DS in mild-to-moderate AD. The DS may be valuable to capture dependence within future clinical dementia trials.

Long-term follow-up of patients immunized with AN1792: reduced functional decline in antibody responders

BACKGROUND

Immunization of patients with Alzheimer's disease (AD) with synthetic amyloid-beta peptide (Abeta(42)) (AN1792) was previously studied in a randomized, double-blind, placebo-controlled phase 2a clinical trial, Study AN1792(QS-21)-201. Treatment was discontinued following reports of encephalitis. One year follow-up revealed that AN1792 antibody responders showed improvements in cognitive measures as assessed by the neuropsychological test battery (NTB) and a decrease in brain volume compared with placebo.

METHODS

A follow-up study, Study AN1792(QS-21)-251, was conducted to assess the long-term functional, psychometric, neuroimaging, and safety outcomes of patients from the phase 2a study 4.6 years after immunization with AN1792. The results were analyzed by comparing patients originally identified as antibody responders in the AN1792 phase 2a study with placebo-treated patients.

RESULTS

One hundred and fifty-nine patients/caregivers (30 placebo; 129 AN1792) participated in this follow-up study. Of the 129 AN1792-treated patients, 25 were classified in the phase 2a study as antibody responders (anti-AN1792 titers > or = 1:2,200 at any time after the first injection). Low but detectable, sustained anti-AN1792 titers were found in 17 of 19 samples obtained from patients classified as antibody responders in the phase 2a study. No detectable anti-AN1792 antibodies were found in patients not classified as antibody responders in the phase 2a study. Significantly less decline was observed on the Disability Assessment for Dementia scale among antibody responders than placebo-treated patients (p=0.015) after 4.6 years. Significant differences in favor of responders were also observed on the Dependence Scale (p=0.033). Of the small number of patients who underwent a follow-up MRI, antibody responders showed similar brain volume loss during the follow-up period subsequent to the AN1792 phase 2a study compared with placebo-treated patients.

CONCLUSIONS

Approximately 4.6 years after immunization with AN1792, patients defined as responders in the phase 2a study maintained low but detectable, sustained anti-AN1792 antibody titers and demonstrated significantly reduced functional decline compared with placebo-treated patients. Brain volume loss in antibody responders was not significantly different from placebo-treated patients approximately 3.6 years from the end of the original study. No further cases of encephalitis were noted. These data support the hypothesis that Abeta immunotherapy may have long-term functional benefits.

Bridging from clinical endpoints to estimates of treatment value for external decision makers

AIM

While clinical endpoints provide important information on the efficacy of treatment in controlled conditions, they often are not relevant to decision makers trying to gauge the potential economic impact or value of new treatments. Therefore, it is often necessary to translate changes in cognition, function or behavior into changes in cost or other measures, which can be problematic if not conducted in a transparent manner. The Dependence Scale (DS), which measures the level of assistance a patient requires due to AD-related deficits, may provide a useful measure of the impact of AD progression in a way that is relevant to patients, providers and payers, by linking clinical endpoints to estimates of cost effectiveness or value. The aim of this analysis was to test the association of the DS to clinical endpoints and AD-related costs.

METHOD

The relationship between DS score and other endpoints was explored using the Predictors Study, a large, multi-center cohort of patients with probable AD followed annually for four years. Enrollment required a modified Mini-Mental State Examination (mMMS) score >or= 30, equivalent to a score of approximately >or= 16 on the MMSE. DS summated scores (range: 0- 15) were compared to measures of cognition (MMSE), function (Blessed Dementia Rating Scale, BDRS, 0-17), behavior, extrapyramidal symptoms (EPS), and psychotic symptoms (illusions, delusions or hallucinations). Also, estimates for total cost (sum of direct medical cost, direct non-medical cost, and cost of informal caregivers' time) were compared to DS scores.

RESULTS

For the 172 patients in the analysis, mean baseline scores were: DS: 5.2 (SD: 2.0), MMSE: 23.0 (SD: 3.5), BDRS: 2.9 (SD: 1.3), EPS: 10.8%, behavior: 28.9% psychotic symptoms: 21.1%. After 4 years, mean scores were: DS: 8.9 (SD: 2.9), MMSE: 17.2 (SD: 4.7), BDRS: 5.2 (SD: 1.4), EPS: 37.5%, behavior: 60.0%, psychotic symptoms: 46.7%. At baseline, DS scores were significantly correlated with MMSE (r=-0.299, p < 0.01), BDRS (r=0.610, p < 0.01), behavior (r=.2633, p=0.0005), EPS (r=0.1910, p=0.0137) and psychotic symptoms (r=0.253, p < 0.01); and at 4-year follow-up, DS scores were significantly correlated with MMSE (r=-0.3705, p=0.017), BDRS (r=0.6982, p < 0.001). Correlations between DS and behavior (-0.0085, p=0.96), EPS (r=0.3824, p=0.0794), psychotic symptoms (r=0.130, ns) were not statistically significant at follow-up. DS scores were also significantly correlated with total costs at baseline (r=0.2615, p=0.0003) and follow-up (r=0.3359, p=0.0318).

DISCUSSION

AD is associated with deficits in cognition, function and behavior, thus it is imperative that these constructs are assessed in trials of AD treatment. However, assessing multiple endpoints can lead to confusion for decision makers if treatments do not impact all endpoints similarly, especially if the measures are not used typically in practice. One potential method for translating these deficits into a more meaningful outcome would be to identify a separate construct, one that takes a broader view of the overall impact of the disease. Patient dependence, as measured by the DS, would appear to be a reasonable choice - it is associated with the three clinical endpoints, as well as measures of cost (medical and informal), thereby providing a bridge between measures of clinical efficacy and value in a single, transparent measure.