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Clin Neuropsychol. 2017 Aug - Oct;31(6-7):1188-1203. doi: 10.1080/13854046.2017.1349931. Epub 2017 Jul 5.

An evidence-based approach to the creation of normative data: base rates of impaired scores within a brief neuropsychological battery argue for age corrections, but against corrections for medical conditions.

Author information

1
a Department of Psychology , University of Saskatchewan , Saskatoon , Canada.
2
b Institute on Aging & Lifelong Health, University of Victoria , Victoria , Canada.
3
c School of Psychology, Laval University and Centre de recherche de l'Institut universitaire en santé mentale de Québec , Québec City , Canada.
4
d Department of Health Research Methods, Evidence, and Impact , McMaster University , Hamilton , Canada.
5
e School of Psychology, University of Ottawa & Bruyère Research Institute , Ottawa , Canada.
6
f Department of Epidemiology and Biostatistics and Occupational Health , McGill University , Montreal , Canada.
7
g Department of Community Health and Epidemiology , Dalhousie University , Halifax , Canada.
8
h Faculty of Health Sciences, Department of Health Research Methods, Evidence and Impact, McMaster Institute for Research on Aging & Labarge Centre for Mobility in Aging , McMaster University , Hamilton , Canada.

Erratum in

Abstract

OBJECTIVE:

We detail a new approach to the creation of normative data for neuropsychological tests. The traditional approach to normative data creation is to make demographic adjustments based on observations of correlations between single neuropsychological tests and selected demographic variables. We argue, however, that this does not describe the implications for clinical practice, such as increased likelihood of misclassification of cognitive impairment, nor does it elucidate the impact on decision-making with a neuropsychological battery.

METHOD:

We propose base rate analyses; specifically, differential base rates of impaired scores between theoretical and actual base rates as the basis for decisions to create demographic adjustments within normative data. Differential base rates empirically describe the potential clinical implications of failing to create an appropriate normative group. We demonstrate this approach with data from a short telephone-administered neuropsychological battery given to a large, neurologically healthy sample aged 45-85 years old. We explored whether adjustments for age and medical conditions were warranted based on differential base rates of spuriously impaired scores.

CONCLUSIONS:

Theoretical base rates underestimated the frequency of impaired scores in older adults and overestimated the frequency of impaired scores in younger adults, providing an evidence base for the creation of age-corrected normative data. In contrast, the number of medical conditions (numerous cardiovascular, hormonal, and metabolic conditions) was not related to differential base rates of impaired scores. Despite a small correlation between number of medical conditions and each neuropsychological variable, normative adjustments for number of medical conditions does not appear warranted. Implications for creation of normative data are discussed.

KEYWORDS:

CLSA; Normative data; base rates; demographic adjustments; medical conditions

PMID:
28679302
DOI:
10.1080/13854046.2017.1349931
[Indexed for MEDLINE]

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