Memantine in patients with moderate to severe Alzheimer's disease: meta-analyses using realistic definitions of response

BACKGROUND/AIMS

We aimed to develop realistic definitions of clinical worsening in advanced Alzheimer's disease (AD) and to use them in a post hoc responder analysis of memantine.

METHODS

2,340 patients with moderate to severe AD (Mini-Mental State Examination <20) were included from 9 multicentre, 16- to 28-week, randomised, double-blind, placebo-controlled studies of memantine 20 mg/day versus placebo. Responder meta-analyses were performed, with definitions of response based on minimally important differences (MIDs) on cognitive, functional, and global assessment scales. Validated or established MIDs were used where available; otherwise, MIDs were estimated by a data-driven approach, using data from our moderate to severe AD population.

RESULTS

Patients with moderate to severe AD treated with memantine had a lower incidence of worsening from baseline to endpoint than patients treated with placebo, in cognition [24.4 vs. 35.0%; odds ratio (OR) = 0.60; p < 0.001], function (38.1 vs. 43.4%; OR = 0.81; p = 0.01), global status (39.8 vs. 48.6%; OR = 0.70; p < 0.001), and in a combined 'triple' worsening measure (9.4 vs. 16.1%; OR = 0.54; p < 0.001).

CONCLUSIONS

New definitions of clinical worsening based on MIDs represent a more realistic functional decline in advanced stages of AD. Results of this new analysis show that memantine reduces the incidence of clinical worsening in key symptomatic domains in moderate to severe AD.

Memantine in patients with Alzheimer's disease receiving donepezil: new analyses of efficacy and safety for combination therapy

Introduction

Memantine and cholinesterase inhibitors potentially offer additional benefits in Alzheimer's disease (AD) when used together. This study assessed the efficacy and safety of combination treatment with memantine added to stable donepezil in patients with moderate to severe AD, and in a subset with moderate AD.

Methods

Post hoc meta-analyses of data combined from two 24-week, randomised, double-blind, placebo-controlled trials of memantine 20 mg/day versus placebo, added to a stable cholinesterase inhibitor, were conducted. Data were included for all patients receiving donepezil 10 mg/day with Mini-Mental State Examination (MMSE) scores < 20 (n = 510). Efficacy was assessed using measures of cognition, function, and global status. Furthermore, marked clinical worsening, defined as concurrent deterioration from baseline in the three main efficacy domains, and safety, measured by treatment-emergent adverse events, were assessed. Analyses were performed for patients with moderate to severe AD (MMSE 5-19; MOD-SEV subgroup), and also for patients with moderate AD (MMSE 10-19; MOD subgroup; n = 367).

Results

At week 24, in the MOD-SEV subgroup, patients receiving memantine added to donepezil significantly outperformed those receiving placebo added to donepezil in measures of cognition (P < 0.0001), function (P = 0.02), and global status (P = 0.010), with standardised mean differences (SMDs) of 0.36, 0.21, and 0.23, respectively (all last observation carried forward). Similarly, in the MOD subgroup, significant benefits were observed for cognition (P = 0.008), function (P = 0.04) and global status (P = 0.008), with SMDs of 0.28, 0.21, and 0.28, respectively. Significantly fewer patients receiving memantine added to donepezil showed marked clinical worsening than those receiving placebo added to donepezil, in both subgroups (MOD-SEV: 8.7% versus 20.4%, P = 0.0002; MOD: 5.9% versus 15.0%, P = 0.006). The incidence of adverse events was similar between treatment groups.

Conclusions

These results support and extend previous evidence that combination treatment with memantine added to stable donepezil in patients with moderate AD, and in those with moderate to severe AD, is associated with significant benefits in reducing 24-week decline in cognition, function and global status. Combination treatment produces substantially reduced rates of marked clinical worsening, has good safety and tolerability, and generates effect sizes that are both statistically significant and clinically meaningful.

Efficacy of memantine in delaying clinical worsening in Alzheimer's disease (AD): responder analyses of nine clinical trials with patients with moderate to severe AD

OBJECTIVE

Responder analyses are of relevance to evaluate the benefits of a medical treatment. The aim of the current paper is to analyse the response of patients with moderate to severe Alzheimer's disease (AD) to memantine, and clinical relevant response is defined as a delay of clinical worsening.

METHODS

Post hoc analyses were performed over the results of nine individual clinical trials including 2506 study patients. Overall, estimates of the odds ratio (OR) and corresponding confidence intervals were based upon a random-effect model for three individual domains (cognition, activities of daily living and clinical global impression). In addition, a combined responder criterion (triple response) includes all three individual domains.

RESULTS

Responder analyses have shown that AD patients treated with memantine benefited from a significant delay of clinical worsening compared with placebo-treated patients, and fewer patients faced clinical worsening in the relevant domains cognition (24.6% vs 36.2%, p < 0.001), activities of daily living (56.2% vs 61.6%, p < 0.05) and global impression of change (40.9% vs 49.8, p < 0.001). In addition, response to treatment on the combined domains (triple response) was significantly in favour of memantine compared with placebo, with fewer patients showing clinical worsening (11.0% vs 20.4%, p < 0.001).

CONCLUSIONS

Treatment with memantine delays clinical worsening in patients with moderate to severe AD when compared with placebo. This effect was seen in single domains (cognition, functional abilities and clinical global impression) as well as in the combination of these domains. The consistent results prove the beneficial effects of memantine in moderate to severe AD patients.

A randomized, double-blind, placebo-controlled clinical trial to evaluate the efficacy and safety of neramexane in patients with moderate to severe subjective tinnitus

Background

Neramexane is a new substance that exhibits antagonistic properties at α₉α₁₀ cholinergic nicotinic receptors and N-methyl-D-aspartate receptors, suggesting potential efficacy in the treatment of tinnitus.

Methods

A total of 431 outpatients with moderate to severe subjective tinnitus (onset 3-18 months before screening) were assigned randomly to receive either placebo or neramexane mesylate (25 mg/day, 50 mg/day and 75 mg/day) for 16 weeks, with assessment at 4-week intervals. The primary (intention-to-treat) efficacy analysis was based on the change from baseline in Week 16 in the total score of the adapted German short version of the validated Tinnitus Handicap Inventory questionnaire (THI-12).

Results

Compared with placebo, the largest improvement was achieved in the 50 mg/d neramexane group, followed by the 75 mg/d neramexane group. This treatment difference did not reach statistical significance at the pre-defined endpoint in Week 16 (p = 0.098 for 50 mg/d; p = 0.289 for 75 mg/d neramexane), but consistent numerical superiority of both neramexane groups compared with placebo was observed. Four weeks after the end of treatment, THI-12 scores in the 50 mg/d group were significantly better than those of the controls. Secondary efficacy variables supported this trend, with p values of < 0.05 for the 50 mg/d neramexane group associated with the functional-communicational subscores of the THI-12 and the assessments of tinnitus annoyance and tinnitus impact on life as measured on an 11-point Likert-like scale. No relevant changes were observed for puretone threshold, for tinnitus pitch and loudness match, or for minimum masking levels. The 25 mg/d neramexane group did not differ from placebo. Neramexane was generally well tolerated and had no relevant influence on laboratory values, electrocardiography and vital signs. Dizziness was the most common adverse event and showed a clear dose-dependence.

Conclusions

This study demonstrated the safety and tolerability of neramexane treatment in patients with moderate to severe tinnitus. The primary efficacy variable showed a trend towards improvement of tinnitus suffering in the medium- and high-dose neramexane groups. This finding is in line with consistent beneficial effects observed in secondary assessment variables. These results allow appropriate dose selection for further studies.

Trial Registration

ClinicalTrials.gov NCT00405886

Memantine in moderate to severe Alzheimer's disease: a meta-analysis of randomised clinical trials

The efficacy of memantine in Alzheimer's disease (AD) has been investigated in multiple randomised, placebo-controlled phase III trials. Recently, the indication label for memantine in Europe was extended to cover patients with moderate to severe AD, i.e. Mini-Mental State Exam total scores below 20. The efficacy data for memantine in this patient subgroup has been summarised by a meta-analysis of 1,826 patients in six trials. Efficacy was assessed using measures of global status (Clinician's Interview-Based Impression of Change Plus Caregiver Input), cognition (Alzheimer's Disease Assessment Scale - Cognitive Subscale, or Severe Impairment Battery), function (Alzheimer's Disease Cooperative Study Activities of Daily Living 19- or 23-item scale), and behaviour (Neuropsychiatric Inventory). Results (without replacement of missing values) showed statistically significant effects for memantine (vs. placebo) in each domain. Memantine was well tolerated, and the overall incidence rates of adverse events were comparable to placebo. This meta-analysis supports memantine's clinically relevant efficacy in patients with moderate to severe AD.

Effects of memantine on behavioural symptoms in Alzheimer's disease patients: an analysis of the Neuropsychiatric Inventory (NPI) data of two randomised, controlled studies

INTRODUCTION

Behavioural symptoms are common in moderate to severe Alzheimer's disease (AD). We have analysed the databases of two randomised studies with regard to the effects of memantine treatment on behavioural symptoms, measured using the 12-item version of the Neuropsychiatric Inventory (NPI).

SUBJECTS

The monotherapy study (memantine only) reported by Reisberg et al. (2003) involved 252 patients with baseline MMSE total score of between 3 and 14, whereas the combination study (memantine and donepezil) reported by Tariot et al. (2004) comprised 404 patients with MMSE scores of between 5 and 14. In both studies, patients received 10 mg memantine b.i.d. or matching placebo, and lived in the community.

METHODS

For both studies NPI total and individual domains scores were analysed in the ITT population. For the monotherapy study a dichotomised analysis was performed separately for patients who had behavioural symptoms at baseline and for those without pre-existing symptoms. Furthermore, a factor analysis was used to identify any behavioural clusters within the patient population.

RESULTS

In both studies, the change in NPI total scores at endpoint was consistently in favour of memantine treatment, reaching statistical significance in the combination study (p = 0.002). Memantine treatment showed a significant beneficial effect in comparison to placebo treatment in the NPI agitation/aggression domain in both studies (p = 0.008; p = 0.001). The dichotomised analysis of the monotherapy study showed that there was significantly less agitation/aggression emerging in the memantine-treated group compared to placebo (p = 0.003). Factor analysis showed that hyperactivity accounted for 27% of the data variance.

CONCLUSIONS

Memantine has a beneficial effect on the behavioural symptoms of patients with moderate to severe AD, with the most pronounced effect on agitation/aggression.

Specific functional effects of memantine treatment in patients with moderate to severe Alzheimer's disease

Treatment of Alzheimer's disease (AD) that combats progressive functional deterioration can improve the patient's quality of life and reduce caregiver burden. Memantine, a moderate affinity N-methyl-D-aspartate receptor antagonist, reduces global deterioration in AD patients and provides cognitive and functional benefits relative to placebo. Two previous studies reported statistically significant benefits of memantine for overall functional ability on the Alzheimer Disease Cooperative Study Activities of Daily Living Inventory modified for severe dementia (ADCS-ADL(19)), Functional Assessment Staging, and G2 scale. The present study reports a single-item analysis of the ADL scales from the two trials and shows that patients treated with memantine demonstrated a numerical advantage over placebo on all items assessed. These results help to translate the positive effects of memantine into specific aspects of functional ability, information that is relevant to AD patients and their families as well as to researchers interested in the assessment of functional ability in AD clinical trials.

Resource utilisation and cost analysis of memantine in patients with moderate to severe Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a devastating illness that causes enormous emotional stress to affected families and is associated with substantial medical and nonmedical costs.

OBJECTIVE

To determine the effects of 28 weeks of memantine treatment for patients with AD on resource utilisation and costs.

STUDY DESIGN AND METHODS

Multicentre, prospective, double-blind, randomised, placebo-controlled clinical trial performed in the US. The Wilcoxon-Mann-Whitney test was used to examine the resource utilisation variables and logistic regression models were used for multivariate resource utilisation analyses. Analysis of covariance (ANCOVA) models (log and non-log) were computed to examine costs from a societal perspective. All costs were calculated in 1999 US dollars.

STUDY POPULATION

Outpatients with moderate to severe AD. Overall, 252 patients received randomised treatment, and 166 patients (placebo n = 76, memantine n = 90) formed the treated-per-protocol (TPP) subset for the health economic analyses, on which the main cost analysis was based.

MAIN OUTCOME MEASURE

Resource Utilisation in Dementia (RUD) scale, measuring patient and caregiver resource utilisation, and various sources for cost calculations.

RESULTS

Controlling for baseline differences between the groups, significantly less caregiver time was needed for patients receiving memantine than for those receiving placebo (difference 51.5 hours per month; 95% CI -95.27, -7.17; p = 0.02). Analysis of residential status also favoured memantine: time to institutionalisation (p = 0.052) and institutionalisation at week 28 (p = 0.04 with the chi-square test). Total costs from a societal perspective were lower in the memantine group (difference dollars US 1089.74/month [non-overlapping 95% CI for treatment difference -1954.90, -224.58]; p = 0.01). The main differences between the groups were total caregiver costs (dollars US-823.77/month; p = 0.03) and direct nonmedical costs (dollars US-430.84/month; p = 0.07) favouring memantine treatment. Patient direct medical costs were higher in the memantine group (p < 0.01), mainly due to the cost of memantine.

CONCLUSION

Resource utilisation and total health costs were lower in the memantine group than the placebo group. The results suggest that memantine treatment of patients with moderate to severe AD is cost saving from a societal perspective.