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Measuring the quality of life in mild to very severe dementia: Testing the inter-rater and intra-rater reliability of the German version of the QUALIDEM

Published online by Cambridge University Press:  10 February 2014

Martin Nikolaus Dichter ,
Christian G. G. Schwab ,
Gabriele Meyer ,
Sabine Bartholomeyczik ,
Olga Dortmann  and
Margareta Halek
Martin Nikolaus Dichter*
Affiliation:
German Center for Neurodegenerative Diseases (DZNE), Witten, Germany School of Nursing Science, Witten/Herdecke University, Witten, Germany
Christian G. G. Schwab
Affiliation:
German Center for Neurodegenerative Diseases (DZNE), Witten, Germany School of Nursing Science, Witten/Herdecke University, Witten, Germany
Gabriele Meyer
Affiliation:
School of Nursing Science, Witten/Herdecke University, Witten, Germany Institute of Health and Nursing Research, Medical Faculty, Martin-Luther-University Halle-Wittenberg, Germany
Sabine Bartholomeyczik
Affiliation:
School of Nursing Science, Witten/Herdecke University, Witten, Germany
Olga Dortmann
Affiliation:
German Center for Neurodegenerative Diseases (DZNE), Witten, Germany School of Nursing Science, Witten/Herdecke University, Witten, Germany
Margareta Halek
Affiliation:
German Center for Neurodegenerative Diseases (DZNE), Witten, Germany School of Nursing Science, Witten/Herdecke University, Witten, Germany
*
Correspondence should be addressed to: Martin Nikolaus Dichter, German Center for Neurodegenerative Diseases (DZNE), Stockumer Straße 12, 58453 Witten, Germany. Phone: +49 2302926-253; Fax: +49 2302926-239. Email: Martin.Dichter@dzne.de.
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Abstract

Background:

Quality of life (Qol) is an increasingly used outcome measure in dementia research. The QUALIDEM is a dementia-specific and proxy-rated Qol instrument. We aimed to determine the inter-rater and intra-rater reliability in residents with dementia in German nursing homes.

Methods:

The QUALIDEM consists of nine subscales that were applied to a sample of 108 people with mild to severe dementia and six consecutive subscales that were applied to a sample of 53 people with very severe dementia. The proxy raters were 49 registered nurses and nursing assistants. Inter-rater and intra-rater reliability scores were calculated on the subscale and item level.

Results:

None of the QUALIDEM subscales showed strong inter-rater reliability based on the single-measure Intra-Class Correlation Coefficient (ICC) for absolute agreement ≥ 0.70. Based on the average-measure ICC for four raters, eight subscales for people with mild to severe dementia (care relationship, positive affect, negative affect, restless tense behavior, social relations, social isolation, feeling at home and having something to do) and five subscales for very severe dementia (care relationship, negative affect, restless tense behavior, social relations and social isolation) yielded a strong inter-rater agreement (ICC: 0.72–0.86). All of the QUALIDEM subscales, regardless of dementia severity, showed strong intra-rater agreement. The ICC values ranged between 0.70 and 0.79 for people with mild to severe dementia and between 0.75 and 0.87 for people with very severe dementia.

Conclusions:

This study demonstrated insufficient inter-rater reliability and sufficient intra-rater reliability for all subscales of both versions of the German QUALIDEM. The degree of inter-rater reliability can be improved by collaborative Qol rating by more than one nurse. The development of a measurement manual with accurate item definitions and a standardized education program for proxy raters is recommended.

Keywords

quality of lifenursing homesGermanydementiapsychometric propertiesreliabilitylong-term careproxy-measurement
Type
Research Article
Information
International Psychogeriatrics , Volume 26 , Issue 5 , May 2014 , pp. 825 - 836
Copyright
Copyright © International Psychogeriatric Association 2014 

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