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

Assessing quality of life in Alzheimer's disease: Implications for clinical trials

Introduction Characterization of the quality of life (QOL) in Alzheimer's disease (AD) scale within the context of a clinical trial may inform its applicability in future trials. Methods Using data from 1322 patients enrolled in two phase-III studies (EXPEDITION 1 [NCT00905372] and 2 [NCT00904683]) of intravenous solanezumab in outpatients with mild AD dementia, correlations between patient- and caregiver-assessed QOL and between QOL and clinical outcome measures were examined. Longitudinal effects of solanezumab over 80 weeks were explored, controlling for patient and caregiver baseline characteristics. Results Caregivers rated patients' QOL worse than did patients themselves. Patients' QOL was correlated, albeit modestly, with clinical/health measures. Patients' QOL changed minimally over 80 weeks, although a treatment effect of solanezumab on QOL was detected. Discussion Further investigations are needed to determine the optimal measures with which to quantify and qualify QOL of patients with mild AD

Longitudinal Medication Usage in Alzheimer Disease Patients

This study examined in detail patterns of cholinesterase inhibitors (ChEIs) and memantine use and explored the relationship between patient characteristics and such use. Patients with probable Alzheimer disease AD (n=201) were recruited from the Predictors Study in 3 academic AD centers and followed from early disease stages for up to 6 years. Random effects logistic regressions were used to examine effects of patient characteristics on ChEIs/memantine use over time. Independent variables included measures of function, cognition, comorbidities, the presence of extrapyramidal signs, psychotic symptoms, age, sex, and patient's living situation at each interval. Control variables included assessment interval, year of study entry, and site. During a 6-year study period, rate of ChEIs use decreased (80.6% to 73.0%) whereas memantine use increased (2.0% to 45.9%). Random effects logistic regression analyses showed that ChEI use was associated with better function, no psychotic symptoms, and younger age. Memantine use was associated with better function, poorer cognition, living at home, later assessment interval, and later year of study entry. Results suggest that high rate of ChEI use and increasing memantine use over time are consistent with current practice guidelines of initiation of ChEIs in mild-to-moderate AD patients and initiation of memantine in moderate-to-severe patients

Utilization of Antihypertensives, Antidepressants, Antipsychotics, and Hormones in Alzheimer Disease

This study explores the longitudinal relationship between patient characteristics and use of 4 drug classes (antihypertensives, antidepressants, antipsychotics, and hormones) that showed significant changes in use rates over time in patients with Alzheimer disease. Patient/caregiver-reported prescription medication usage was categorized by drug class for 201 patients from the Predictors Study. Patient characteristics included use of cholinesterase inhibitors and/or memantine, function, cognition, living situation, baseline age, and sex. Assessment interval, year of study entry, and site were controlled for. Before adjusting for covariates, useage increased for antihypertensives (47.8% to 62.2%), antipsychotics (3.5% to 27.0%), and antidepressants (32.3% to 40.5%); use of hormones decreased (19.4% to 5.4%). After controlling for patient characteristics, effects of time on the use of antidepressants were no longer significant. Antihypertensive use was associated with poorer functioning, concurrent use of memantine, and older age. Antipsychotic use was associated with poorer functioning and poorer cognition. Antidepressant use was associated with younger age, poorer functioning, and concurrent use of cholinesterase inhibitors and memantine. Hormone use was associated with being female and younger age. Findings suggest accurate modeling of the Alzheimer disease treatment paradigm for certain subgroups of patients should include antihypertensives and antipsychotics in addition to cholinesterase inhibitors and memantine

How to deal with missing longitudinal data in cost of illness analysis in Alzheimer’s disease—suggestions from the GERAS observational study

BACKGROUND: Missing data are a common problem in prospective studies with a long follow-up, and the volume, pattern and reasons for missing data may be relevant when estimating the cost of illness. We aimed to evaluate the effects of different methods for dealing with missing longitudinal cost data and for costing caregiver time on total societal costs in Alzheimer's disease (AD). METHODS: GERAS is an 18-month observational study of costs associated with AD. Total societal costs included patient health and social care costs, and caregiver health and informal care costs. Missing data were classified as missing completely at random (MCAR), missing at random (MAR) or missing not at random (MNAR). Simulation datasets were generated from baseline data with 10-40 % missing total cost data for each missing data mechanism. Datasets were also simulated to reflect the missing cost data pattern at 18 months using MAR and MNAR assumptions. Naïve and multiple imputation (MI) methods were applied to each dataset and results compared with complete GERAS 18-month cost data. Opportunity and replacement cost approaches were used for caregiver time, which was costed with and without supervision included and with time for working caregivers only being costed. RESULTS: Total costs were available for 99.4 % of 1497 patients at baseline. For MCAR datasets, naïve methods performed as well as MI methods. For MAR, MI methods performed better than naïve methods. All imputation approaches were poor for MNAR data. For all approaches, percentage bias increased with missing data volume. For datasets reflecting 18-month patterns, a combination of imputation methods provided more accurate cost estimates (e.g. bias: -1 % vs -6 % for single MI method), although different approaches to costing caregiver time had a greater impact on estimated costs (29-43 % increase over base case estimate). CONCLUSIONS: Methods used to impute missing cost data in AD will impact on accuracy of cost estimates although varying approaches to costing informal caregiver time has the greatest impact on total costs. Tailoring imputation methods to the reason for missing data will further our understanding of the best analytical approach for studies involving cost outcomes

Modeling screening, prevention, and delaying of Alzheimer's disease: an early-stage decision analytic model

<p>Abstract</p> <p>Background</p> <p>Alzheimer's Disease (AD) affects a growing proportion of the population each year. Novel therapies on the horizon may slow the progress of AD symptoms and avoid cases altogether. Initiating treatment for the underlying pathology of AD would ideally be based on biomarker screening tools identifying pre-symptomatic individuals. Early-stage modeling provides estimates of potential outcomes and informs policy development.</p> <p>Methods</p> <p>A time-to-event (TTE) simulation provided estimates of screening asymptomatic patients in the general population age ≥55 and treatment impact on the number of patients reaching AD. Patients were followed from AD screen until all-cause death. Baseline sensitivity and specificity were 0.87 and 0.78, with treatment on positive screen. Treatment slowed progression by 50%. Events were scheduled using literature-based age-dependent incidences of AD and death.</p> <p>Results</p> <p>The base case results indicated increased AD free years (AD-FYs) through delays in onset and a reduction of 20 AD cases per 1000 screened individuals. Patients completely avoiding AD accounted for 61% of the incremental AD-FYs gained. Total years of treatment per 1000 screened patients was 2,611. The number-needed-to-screen was 51 and the number-needed-to-treat was 12 to avoid one case of AD. One-way sensitivity analysis indicated that duration of screening sensitivity and rescreen interval impact AD-FYs the most. A two-way sensitivity analysis found that for a test with an extended duration of sensitivity (15 years) the number of AD cases avoided was 6,000-7,000 cases for a test with higher sensitivity and specificity (0.90,0.90).</p> <p>Conclusions</p> <p>This study yielded valuable parameter range estimates at an early stage in the study of screening for AD. Analysis identified duration of screening sensitivity as a key variable that may be unavailable from clinical trials.</p

Effect of diabetes on caregiver burden in an observational study of individuals with Alzheimer’s disease

Background The burden on caregivers of patients with Alzheimer’s disease (AD) is associated with the patient’s functional status and may also be influenced by chronic comorbid medical conditions, such as diabetes. This post-hoc exploratory analysis assessed whether comorbid diabetes in patients with AD affects caregiver burden, and whether caregivers with diabetes experience greater burden than caregivers without diabetes. Caregiver and patient healthcare resource use (HCRU) were also assessed. Methods Baseline data from the GERAS observational study of patients with AD and their caregivers (both n = 1495) in France, Germany and the UK were analyzed. Caregiver burden was assessed using the Zarit Burden Interview (ZBI). Caregiver time on activities of daily living (ADL: basic ADL; instrumental ADL, iADL) and supervision (hours/month), and caregiver and patient HCRU (outpatient visits, emergency room visits, nights hospitalized) were assessed using the Resource Utilization in Dementia instrument for the month before the baseline visit. Regression analyses were adjusted for relevant covariates. Time on supervision and basic ADL was analyzed using zero-inflated negative binomial regression. Results Caregivers of patients with diabetes (n = 188) were younger and more likely to be female (both p < 0.05), compared with caregivers of patients without diabetes (n = 1307). Analyses showed caregivers of patients with diabetes spent significantly more time on iADL (+16 %; p = 0.03; increases were also observed for basic ADL and total caregiver time but did not reach statistical significance) and had a trend towards increased ZBI score. Patients with diabetes had a 63 % increase in the odds of requiring supervision versus those without diabetes (p = 0.01). Caregiver and patient HCRU did not differ according to patient diabetes. Caregivers with diabetes (n = 127) did not differ from those without diabetes (n = 1367) regarding burden/time, but caregivers with diabetes had a 91 % increase in the odds of having outpatient visits (p = 0.01). Conclusions This cross-sectional analysis found caregiver time on iADL and supervision was higher for caregivers of patients with AD and diabetes versus without diabetes, while HCRU was unaffected by patient diabetes. Longitudinal analyses assessing change in caregiver burden over time by patient diabetes status may help clarify the cumulative impact of diabetes and AD dementia on caregiver burden

Alzheimer’s disease severity and its association with patient and caregiver quality of life in Japan: results of a community-based survey

Abstract Background Alzheimer’s disease (AD) dementia, a progressive neurodegenerative disease, exerts significant burden upon patients, caregivers, and healthcare systems globally. The current study investigated the associations between AD dementia patient disease severity and health-related quality of life (HRQoL) of both patients (proxy report) and their caregivers living in Japan, as well as caregiving-related comorbidities such as depression. Methods This cross-sectional study used self-reported data from caregivers of people diagnosed with AD dementia by a healthcare provider in Japan. Caregivers were identified via online panels and invited to participate in an online survey between 2014 and 2015. Caregivers completed survey items for themselves, in addition to providing proxy measures for patients with AD dementia for whom they were caring. Patient and caregiver HRQoL was measured using the EuroQoL 5-Dimension (EQ-5D). Additional outcomes for caregivers of AD dementia patients included the Patient Health Questionnaire (PHQ-9) of depressive symptomology, as well as comorbidities experienced since initiating caregiving for their AD dementia patients. These outcomes were examined as a function of AD dementia severity, as measured by long-term care insurance (LTCI) categories. Bivariate analyses between LTCI and outcomes were conducted using independent t-tests and chi-square tests. Multivariable analyses, controlling for potential confounders, were conducted using generalized linear models (GLMs) specifying a normal distribution. Results Across 300 caregiver respondents, multivariable results revealed that increasing AD dementia severity was significantly associated with poorer patient and caregiver EQ-5D scores and a high proportion of caregivers (30.0%) reported PHQ-9 scores indicative of major depressive disorder (MDD). The most frequent comorbidities experienced after becoming caregivers of AD dementia patients included hypertension (12.7%) and insomnia (11.0%). Depression and other comorbidities did not differ significantly by patient severity. Conclusions The current study provides unique insight into the specific degree of incremental burden associated with increasing AD dementia severity among patients and caregivers alike. Importantly, greater disease severity was associated with poorer quality of life among both patients and caregivers. These results suggest that earlier detection and treatment of AD dementia may provide an opportunity to reduce the burden of disease for patients, caregivers, and society at large

Sensitivity and specificity of the Mini-Mental State Examination for identifying dementia in the oldest-old: The 90+study

OBJECTIVES: To evaluate the sensitivity and specificity of the Mini-Mental State Examination (MMSE) in identifying dementia in the oldest-old when stratified by age and education. DESIGN: Cross-sectional. SETTING: Research clinic and in-home visits. PARTICIPANTS: Population-based sample of adults aged 90 and older (n=435) who are enrolled in the 90+ Study, a longitudinal, population-based study. MEASUREMENTS: Neurological examination to determine dementia diagnosis, MMSE, and demographic data. RESULTS: Receiver operating characteristic (ROC) analyses indicated that the MMSE had high diagnostic accuracy for identifying dementia in subjects aged 90 and older across different age and education groups (area under the ROC curve values ranged from 0.82 to 0.98). A range of possible cutoff values and corresponding sensitivity and specificity are provided for the following age groups: 90-93, 94-96, and &gt;= 97. Age groups were subdivided by educational attainment (&lt;= high school, vocational school or some college, college degree or higher). In subjects aged 90 to 93 with a college degree or higher, the suggested MMSE cutoff score is &lt;= 25 (sensitivity=0.82, specificity=0.80). In those aged 94 to 96 with a college degree or higher, the suggested cutoff is &lt;= 24 (sensitivity=0.85, specificity=0.80). Those aged 97 and older with an education of high school or less had the lowest suggested cutoff &lt;= 22 (sensitivity=0.80, specificity=0.76). CONCLUSION: Overall, the MMSE had good sensitivity and specificity across all age and educational groups. Optimal cutoff points were lower in the older age groups and those with less education, primarily to preserve specificity. This screening instrument is appropriate for use with the oldest-old