Journal
NEUROEPIDEMIOLOGY
Volume 41, Issue 3-4, Pages 208-216Publisher
KARGER
DOI: 10.1159/000354629
Keywords
Africa; HIV; Dementia; Prevalence; Power
Funding
- American Academy of Neurology Practice Research Training Fellowship
- Fogarty International Center of the National Institutes of Health [K01TW008764]
- Fogarty International Clinical Research Fellowship [5 R24 TW00798, 3 R24 TW00798-02S1]
- National Institutes of Health
- Fogarty International Center through Vanderbilt University
- National Cancer Institute
- National Institute on Drug Abuse
- Office of the Director
- National Institute of Mental Health
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Background: Between 0 and 48% of normal HIV-uninfected individuals score below threshold neuropsychological test scores for HIV-associated neurocognitive disorders (HAND) or are false positives. There has been little effort to understand the effect of varied interpretations of research criteria for HAND on false-positive frequencies, prevalence and analytic estimates. Methods:The proportion of normal individuals scoring below Z score thresholds drawn from research criteria for HAND, or false-positive frequencies, was estimated in a normal Kenyan population and a simulated normal population using varied interpretations of research criteria for HAND. We calculated the impact of false-positive frequencies on prevalence estimates and statistical power. Results: False-positive frequencies of 2-74% were observed for asymptomatic neurocognitive impairment/mild neurocognitive disorder and 0-8% for HIV-associated dementia. False-positive frequencies depended on the definition of an abnormal cognitive domain, Z score thresholds and neuropsychological battery size. Misclassification led to clinically important overestimation of prevalence and dramatic de creases in power. Conclusions: Minimizing false-positive frequencies is critical to decrease bias in prevalence estimates and minimize reductions in power in studies of association, particularly for mild forms of HAND. We recommend changing the Z score threshold to for mild impairment, limiting analysis to 3-5 cognitive domains and using the average Z score to define an abnormal domain. (C) 2013 S. Karger AG, Basel
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