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Methodological issues in a cluster-randomized trial to prevent dementia by intensive vascular care
E Richard1, S A Ligthart, E P Moll van Charante
1Academic Medical Center, University of Amsterdam, Department of Neurology, Amsterdam, The Netherlands. e.richard@amc.uva.nl
The Journal of Nutrition, Health & Aging
|March 23, 2010
Summary
This study investigated if intensive vascular care can prevent dementia in older adults. Methodological challenges in cluster-randomized trials, like loss of power due to patient clustering, require careful consideration in study design and analysis.
Area of Science:
- Gerontology
- Clinical Trials
- Vascular Medicine
Background:
- Dementia prevention is a critical public health concern.
- Vascular risk factors are implicated in dementia development.
- Effective interventions targeting vascular health in older adults are needed.
Purpose of the Study:
- To describe methodological issues encountered in a cluster-randomized trial evaluating a multi-component intervention for dementia prevention.
- To assess the impact of intensive vascular care on dementia incidence and other health outcomes in non-demented elderly individuals.
Main Methods:
- A multi-center, open, cluster-randomized controlled trial (preDIVA) involving 3535 non-demented participants aged 70-78.
- General practices were randomized to either standard care or intensive vascular care, with the latter involving 4-monthly nurse visits to manage cardiovascular risk factors.
- Primary outcomes included incident dementia and disability; secondary outcomes comprised mortality, vascular events, cognitive decline, and depression.
Main Results:
- 3535 subjects from 115 general practices were enrolled between May 2006 and February 2009.
- 1658 patients in 52 practices received standard care, while 1877 patients in 63 practices received intensive vascular care.
- The average cluster size was 31 participants per general practice.
Conclusions:
- Clustering of patient data within general practices in cluster-randomized trials can lead to a loss of statistical power, necessitating adjustments in power calculations.
- Competing risks, such as cardiovascular mortality, should be accounted for when evaluating interventions aimed at dementia prevention, especially those involving intensive vascular care.
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