Article

Validity, significance, strengths, limitations, and evidentiary value of real-world clinical data for combination therapy in Alzheimer's disease: comparison of efficacy and effectiveness studies.

Department of Neurology, Massachusetts General Hospital, Boston, Mass 02114, USA.
Neurodegenerative Diseases (Impact Factor: 3.41). 02/2012; 10(1-4):170-4. DOI: 10.1159/000335156
Source: PubMed

ABSTRACT Randomized controlled efficacy trials (RCTs), the scientific gold standard, are required for regulatory approval of Alzheimer's disease (AD) interventions, yet provide limited information regarding real-world therapeutic effectiveness.
To compare the nature of evidence regarding the combination of approved AD treatments from RCTs versus long-term observational controlled studies (LTOCs).
Comparisons of strengths, limitations, and evidence level for monotherapy [cholinesterase inhibitor (ChEI) or memantine] and combination therapy (ChEI + memantine) in RCTs versus LTOCs.
RCTs examined highly selected populations over months. LTOCs collected data across multiple AD stages in large populations over many years. RCTs and LTOCs show similar patterns favoring combination over monotherapy over placebo/no treatment. Long-term combination therapy compared to monotherapy reduced cognitive and functional decline and delayed time to nursing home admission. Persistent treatment was associated with slower decline. While LTOCs used control groups, adjusted for multiple covariates, had higher external validity, and favorable ethical, practical and cost considerations, their limitations included potential selection bias due to lack of placebo comparisons and randomization.
Naturalistic LTOCs provide complementary long-term level II evidence to complement level I evidence from short-term RCTs regarding therapeutic effectiveness in AD that may otherwise be unobtainable. A coordinated strategy/consortium to pool LTOC data from multiple centers to estimate long-term comparative effectiveness, risks/benefits, and costs of AD treatments is needed.

0 Bookmarks
 · 
77 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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. © 2013 S. Karger AG, Basel.
    Dementia and Geriatric Cognitive Disorders 10/2013; 37(1-2):71-85. · 2.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Accurate measurement of cognitive function is critical for understanding the disease course of Alzheimer's disease (AD). Detecting cognitive change over time can be confounded by level of premorbid intellectual function or cognitive reserve and lead to under- or over-diagnosis of cognitive impairment and AD. Statistical models of cognitive performance that include cognitive reserve can improve sensitivity to change and clinical efficacy. We used confirmatory factor analysis to test a four-factor model composed of memory/language, processing speed/executive function, attention, and cognitive reserve factors in a group of cognitively healthy older adults and a group of participants along the spectrum of amnestic mild cognitive impairment to AD (aMCI-AD). The model showed excellent fit for the control group (χ2 = 100; df = 78; CFI = .962; RMSEA = .049) and adequate fit for the aMCI-AD group (χ2 = 1750; df = 78; CFI = .932; RMSEA = .085). Although strict invariance criteria were not met, invariance testing to determine if factor structures are similar across groups yielded acceptable absolute model fits and provide evidence in support of configural, metric, and scalar invariance. These results provide further support for the construct validity of cognitive reserve in healthy and memory impaired older adults. (JINS, 2012, 18, 1-10).
    Journal of the International Neuropsychological Society 10/2012; · 2.70 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background. Acetylcholinesterase (AChE)/cholinesterase (ChE) inhibitors (Is) and memantine are licensed for symptomatic treatment of mild-moderate and moderate-severe forms of Alzheimer's disease (AD), respectively. High doses of the AChE-I donepezil were licensed in the USA for moderate-severe AD, and the association AChE/ChE-Is plus memantine was proposed for AD at this stage. Objectives. This paper has reviewed evidence from clinical trials of the effectiveness of memantine, donepezil, or the two drugs in association in managing moderate-severe AD. Method. Double-blind, placebo-controlled randomized trials (RCTs) using memantine or donepezil alone or in association versus placebo in moderate-severe AD were reviewed. Analysis done in January 2013 considered the years 2007-2012. Results and Conclusion. Only 83 of the 941 papers selected were considered relevant, and only 13 met the criterion of "adequacy and representativeness." Memantine and donepezil lead to improvements in moderate-to-severe AD and the choice between the compounds should be based on their contraindications more than on disease severity. No evidence was found of advantages of the association of memantine-donepezil. The heterogeneity of conditions explored by RCTs, the relatively short time of observation (24-52 weeks), and the different cognitive assessment tools used did not allow comparing properly different trials.
    The Scientific World Journal 01/2013; 2013:925702. · 1.22 Impact Factor

Full-text (2 Sources)

Download
6 Downloads
Available from
Aug 19, 2014