Clinical Outcome Measure Crosswalks in Alzheimer's Disease: A Systematic Review

Convergence and equating norms between the Telephone Interview for Cognitive Status (TICS), the MMSE and the MoCA in an Italian population sample

BACKGROUND

This study aimed at testing the convergence and deriving equating norms between the Telephone Interview for Cognitive Status (TICS) and the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) in an Italian population sample.

METHODS

Four-hundred and eighty two healthy Italian native-speaker (300 females; age: 57.8 ± 15.5, range = 20-94; education: 13.1 ± 3.8, range = 5-25) underwent the TICS (range = 1-41), MMSE and MoCA. An additional Delayed Recall of the 10-word list was administered as the last task of the TICS to compute a further total (TICS&DR; range = 1-51). Convergence between the TICS/TICS&DR and in-person screeners was tested via Bonferroni-corrected Spearman's coefficients, whilst equating norms were derived via a Log-linear Smoothing Equipercentile Equating (LSEE) approach. A two one-sided test (TOST) procedure was run to test the equivalence between empirical and LSEE-derived scores.

RESULTS

TICS scores converged with both MMSE (rs=0.34; p <.001) and MoCA scores (rs=0.42; p <.001)- the same being true for the TICS&DR (MMSE: rs=0.36; p <.001; MoCA: rs=0.42; p <.001). Cross-walks were estimated to derive TICS/TICS&DR scores from the MMSE/MoCA, and vice-versa. The algorithm could not compute the conversions for TICS, MMSE and MoCA scores < 22, <21 and < 14, respectively. TOST procedures revealed that all comparisons yielded equivalence except for those aimed at deriving TICS from MMSE scores and TICS&DR from both the MMSE and the MoCA.

DISCUSSION

The Italian TICS validly captures examinees' cognitive efficiency as measured by MMSE or MoCA; derived cross-walks between the TICS and MMSE/MoCA allows for a flexible use of in-person and telephone-based screeners.

Linking Cognitive Screening Tests in Community-Dwelling Older Adults: Crosswalk between the Montreal Cognitive Assessment-Basic and the Mini-Mental State Examination

OBJECTIVE

To develop the crosswalk between the Montreal Cognitive Assessment-Basic (MoCA-B) and Mini-Mental Status Examination (MMSE) based on a community-dwelling older population to facilitate data synthesis and comparison.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

We used baseline data of 2170 subjects with total MoCA-B and MMSE scores from an ongoing prospective cohort study, the Beijing Longitudinal Disability Survey in Community Elderly (BLINDSCE).

METHODS

The MoCA-B and MMSE were administered by trained assessors. Equipercentile equating was used to develop the conversion table between MoCA-B and MMSE scores in the total sample and subgroups by age, sex, residency, and education level. The mean absolute error (MAE), intraclass correlation coefficient (ICC), and Bland-Altman plot were used to evaluate the linking performance.

RESULTS

MoCA-B and MMSE scores converted bi-directionally for the overall sample and subgroups, with small standardized MAE (SMAE) and high ICC. The linking results between MoCA-B and MMSE scores were consistent across the total sample and the age and sex subgroups, while a 2-score difference was observed within the residency and education subgroups.

CONCLUSIONS AND IMPLICATIONS

This study provides easy-to-use crosswalks between measures of MoCA-B and MMSE with precision among community-dwelling older adults. Our results help to compare and pool data across studies using either of the 2 cognitive screening tests and provide a useful reference to clinicians for better evidence-based practice in patients evaluated using different cognitive tests.

IPECAD Modeling Workshop 2023 Cross-Comparison Challenge on Cost-Effectiveness Models in Alzheimer's Disease

OBJECTIVES

Decision-analytic models assessing the value of emerging Alzheimer's disease (AD) treatments are challenged by limited evidence on short-term trial outcomes and uncertainty in extrapolating long-term patient-relevant outcomes. To improve understanding and foster transparency and credibility in modeling methods, we cross-compared AD decision models in a hypothetical context of disease-modifying treatment for mild cognitive impairment (MCI) due to AD.

METHODS

A benchmark scenario (US setting) was used with target population MCI due to AD and a set of synthetically generated hypothetical trial efficacy estimates. Treatment costs were excluded. Model predictions (10-year horizon) were assessed and discussed during a 2-day workshop.

RESULTS

Nine modeling groups provided model predictions. Implementation of treatment effectiveness varied across models based on trial efficacy outcome selection (clinical dementia rating - sum of boxes, clinical dementia rating - global, mini-mental state examination, functional activities questionnaire) and analysis method (observed severity transitions, change from baseline, progression hazard ratio, or calibration to these). Predicted mean time in MCI ranged from 2.6 to 5.2 years for control strategy and from 0.1 to 1.0 years for difference between intervention and control strategies. Predicted quality-adjusted life-year gains ranged from 0.0 to 0.6 and incremental costs (excluding treatment costs) from -US$66 897 to US$11 896.

CONCLUSIONS

Trial data can be implemented in different ways across health-economic models leading to large variation in model predictions. We recommend (1) addressing the choice of outcome measure and treatment effectiveness assumptions in sensitivity analysis, (2) a standardized reporting table for model predictions, and (3) exploring the use of registries for future AD treatments measuring long-term disease progression to reduce uncertainty of extrapolating short-term trial results by health-economic models.

Methods to crosswalk between cognitive test scores using data from the Alzheimer's Disease Neuroimaging Cohort

INTRODUCTION

Studies use multiple different instruments to measure dementia-related outcomes, making head-to-head comparisons of interventions difficult.

METHODS

To address this gap, we developed two methods to crosswalk estimated treatment effects on cognitive outcomes that are flexible, broadly applicable, and do not rely on strong distributional assumptions.

RESULTS

We present two methods to crosswalk effect estimates using one measure to estimates using another measure, illustrated with global cognitive measures from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Specifically, we develop crosswalks for the following measures and associated change scores over time: the clinical dementia rating scale sum of box (CDR-SB), Montreal Cognitive Assessment (MoCA), and Mini-Mental State Examination (MMSE) scores. Finally, a setting in which crosswalking is not appropriate is illustrated with plasma phosphorylated tau (p-tau) concentration and global cognitive measures.

DISCUSSION

Given the inconsistent collection and reporting of dementia and cognitive outcomes across studies, these crosswalking methods offer a valuable approach to harmonizing and comparing results reported on different scales.

HIGHLIGHTS

Developed methods to crosswalk from one cognitive outcome to another in studies of dementia interventions. Methods illustrated using combinations of global cognitive tests: the CDR-SB, MoCA, and MMSE. Illustrates scenarios where crosswalking may not be appropriate for certain combinations of measures. Crosswalking methods support comparison of interventions with accurate error propagation. Facilitates inclusion of more studies in meta-analyses by increasing data comparability.

Informal care for people with dementia in Europe

INTRODUCTION

Informal care estimates for use in health-economic models are lacking. We aimed to estimate the association between informal care time and dementia symptoms across Europe.

METHODS

A secondary analysis was performed on 13,529 observations in 5,369 persons from 9 European pooled cohort or trial studies in community-dwelling persons with dementia. A mixed regression model was fitted to time spent on instrumental or basic activities of daily living using disease severity and demographic characteristics.

RESULTS

Daily informal care time was 0.5 hours higher in moderate compared to mild and 1.3h higher in severe compared to mild cognitive impairment. Likewise, this was 1.2h and 2.7h for functional disability and 0.3h and 0.6h for behavioral symptoms in the same directions.

DISCUSSION

Estimates can be used in both single- and multi-domain health-economic models for dementia in European settings.

Equating norms between the ALS Cognitive Behavioral Screen (ALS-CBS™) and the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) in non-demented ALS patients

BACKGROUND

The present study aimed at deriving equating norms to estimate scores on the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) based on those on the ALS Cognitive Behavioral Screen (ALS-CBS™) in an Italian cohort of non-demented ALS patients.

METHODS

ALS-CBS™ and ECAS scores of 293 ALS patients without frontotemporal dementia were retrospectively retrieved. Concurrent validity of the ALS-CBS™ towards the ECAS was tested by covarying for demographics, disease duration and severity, presence of C9orf72 hexanucleotide repeat expansion and behavioural features. A linear-smoothing equipercentile equating (LSEE) model was employed to derive ALS-CBS™-to-ECAS cross-walks. Gaps in LSEE-based estimation were managed via a linear regression-based equating approach. Equivalence between empirical and derived ECAS scores was tested via a two-one-sided test (TOST) procedure for the dependent sample.

RESULTS

The ALS-CBS™ predicted the ECAS (β = 0.75), accounting for the vast majority of its variance (60% out of an R² = 0.71). Consistently, a strong, one-to-one linear association between ALS-CBS™ and ECAS scores was detected (r = 0.84; R² = 0.73). The LSEE was able to estimate conversions for the full range of the ALS-CBS™, except for raw scores equal to 1 and 6 - for whom a linear equating-based equation was derived. Empirical ECAS scores were equivalent to those derived with both methods.

DISCUSSION

Italian practitioners and researchers have been herewith provided with valid, straightforward cross-walks to estimate the ECAS based on ALS-CBS™ scores in non-demented ALS patients. Conversions herewith provided will help avoid cross-sectional/longitudinal inconsistencies in test adoption within research, and possibly clinical, settings.

Access to Disease-Modifying Alzheimer's Therapies: Addressing Possible Challenges Using Innovative Payment Models

OBJECTIVES

Aduhelm is the first approved disease-modifying therapies (DMT) for Alzheimer disease (AD). Nevertheless, under current payment models, AD DMTs-especially because they treat broader populations-will pose challenges to patient access since costs may accrue sooner than benefits do. New payment approaches may be needed to address this difference in timing.

METHODS

We use the Future Elderly Model that draws on nationally representative data sets such as the Health and Retirement Study to estimate the potential benefits because of hypothetical AD DMTs in 4 stylized treatment scenarios for patients with mild cognitive impairment or mild AD, and develop a payment model to estimate the accrual of net costs and benefits to private and public payers.

RESULTS

The modeled AD DMTs result in clinical benefit of 0.30 to 0.55 quality-adjusted life-years gained per patient in the baseline treatment scenario and 0.13 to 0.24 quality-adjusted life-years gained per patient in the least optimistic scenario. Private payers may observe a net loss in patients at the age of 61 to 65 years under the status quo (payment upon treatment). Constant and deferred installment payment models resolve this issue.

CONCLUSIONS

Innovative payment solutions, such as installment payments, may be required to address misaligned incentives that AD DMTs may create among patients younger than the age of 65 years and may help address concerns about the timing and magnitude of costs and benefits accrued to private payers.

Crosswalk between the Mini-Mental State Examination and the Telephone Interview for Cognitive Status (TICS-27/30/40)

BACKGROUND

We develop a crosswalk between the Mini-Mental State Examination (MMSE) and Telephone Interview for Cognitive Status (TICS)-27, TICS-30, and TICS-40 for adults 65 years and older.

METHODS

We examined the scores of 1809 participants, with and without cognitive impairment, who completed the MMSE and the TICS assessment in the 2016 Health and Retirement Study and the 2016 Harmonized Cognitive Assessment Protocol study. Crosswalks between MMSE and TICS-27/30/40 were developed via equipercentile equating.

RESULTS

We present crosswalks for MMSE and TICS-27/30/40 for the 65+ population representative of the US elderly. While monotonic, the pattern of the TICS-30 to MMSE crosswalk differs from the other two crosswalks (MMSE to TICS-27/40).

CONCLUSION

Our analysis offers an empirical crosswalk between two commonly used cognitive measures-the MMSE and TICS. Our findings suggest the need for validated and robust measures that allow for the comparison of scores on different cognitive scales.

Addressing Challenges to Alternative Payment Models for New Alzheimer's Disease Therapies for US Commercial Payers

Commercial payers that ultimately decide to cover aducanumab or other Alzheimer's disease therapies may require innovative payment tools to minimize their financial risk given the uncertain benefits and high cost of such treatments. Drawing on the published evidence, we propose two different types of payment models applicable to disease-modifying therapies in Alzheimer's disease, and suggest four strategies to overcome challenges in their implementation. Such strategies range from developing best practices for outcome measurement in Alzheimer's disease, investing in infrastructure to collect real-world data, increasing representativeness of registry data in Alzheimer's disease, and integrating the diagnostic, treatment, and payment landscape. These important steps could make access to emerging therapies in Alzheimer's disease more sustainable in the long term, and could serve as a blueprint for better access to novel therapies in other indications in the future.