gms | German Medical Science

GMS Psycho-Social-Medicine

Gemeinsame Zeitschrift psychosozialer Fachgesellschaften in der Medizin

ISSN 1860-5214

Measuring the quality of life of people with dementia in nursing homes in Germany – the study protocol for the Qol-Dem Project

Die Erfassung der Lebensqualität von Menschen mit Demenz in stationären Altenpflegeeinrichtungen in Deutschland – Studienprotokoll des Qol-Dem Projektes

Research Article

  • corresponding author Martin Nikolaus Dichter - Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Standort Witten, Germany; Department für Pflegewissenschaft, Universität Witten/Herdecke, Witten, Germany
  • author Margareta Halek - Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Standort Witten, Germany
  • author Olga Dortmann - Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Standort Witten, Germany
  • author Gabriele Meyer - Department für Pflegewissenschaft, Universität Witten/Herdecke, Witten, Germany; Martin-Luther-University Halle-Wittenberg, Institute for Health and Nursing Sciences, Halle, Germany
  • author Sabine Bartholomeyczik - Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Standort Witten, Germany; Department für Pflegewissenschaft, Universität Witten/Herdecke, Witten, Germany

GMS Psychosoc Med 2013;10:Doc06

doi: 10.3205/psm000096, urn:nbn:de:0183-psm0000961

Veröffentlicht: 26. Juli 2013

© 2013 Dichter et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen ( Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Background: QUALIDEM is a standardized dementia-specific quality of life (Qol) measurement, which was developed and validated in the Netherlands. A German version has been available since 2008. This study protocol describes the design and methodology for the quality of life of people with dementia (Qol-Dem) project.

Objective: This project aims to evaluate the reliability and validity of the German version of the QUALIDEM.

Method: Due to the lack of both a universal definition of Qol and of standards to verify the validity of Qol measurements, this study is divided into three phases. The aim of the first theoretical phase is the development of a dementia-specific Qol model as a result of a meta-synthesis of qualitative studies. The second empirical phase consists of the three following steps: (a) an investigation of the scalability and internal consistency of the measure, (b) an evaluation of the interrater and intrarater reliability, and (c) an extensive evaluation of the validity of the QUALIDEM. The resulting Qol model (phase 1) will be used for the selection of appropriate comparators for validity testing. In the third phase, the QUALIDEM will be adapted, if necessary, based on the knowledge generated in the first two phases.

Conclusion: The findings of the Qol-Dem project should deliver an accurate assessment of the psychometric properties of the German version of the QUALIDEM. The results will contribute to the further development of the instrument. Furthermore, the results will contribute to the theoretical development of the concept of Qol among people with dementia.

Keywords: quality of life, dementia, nursing homes, psychometrics, proxy-assessment, meta-synthesis, QUALIDEM


Hintergrund: Das standardisierte demenzspezifische Lebensqualitätsinstrument QUALIDEM wurde in den Niederlanden entwickelt und validiert. Eine deutsche Übersetzung des Fragebogens liegt seit 2008 vor. Das vorliegende Studienprotokoll beschreibt Design und Methode des Quality of life of people with dementia (Qol-Dem) Projektes.

Zielsetzung: Ziel dieses Projektes ist die Untersuchung der Reliabilität und Validität der deutschsprachigen QUALIDEM-Version.

Methodik: Da eine allgemeingültige Definition der Lebensqualität von Menschen mit Demenz ebenso wie ein Standard zur Untersuchung der Validität von Lebensqualitätsinstrumenten fehlt, ist die Studie in drei Phasen unterteilt: Ziel der ersten theoretischen Phase ist die Entwicklung eines Modells zur Lebensqualität von Menschen mit Demenz als Ergebnis einer Meta-Synthese qualitativer Studien. Die zweite empirische Phase besteht aus drei Schritten: (a) einer Untersuchung der Skalierbarkeit und Internen Konsistenz, (b) einer Evaluation der Interrater- und Intrarater-Reliabilität und (c) einer intensiven Überprüfung der Validität des QUALIDEM. Ausgehend von dem entwickelten Lebensqualitätsmodell aus Phase 1 erfolgt die Auswahl geeigneter Vergleichskonstrukte zur Untersuchung der Validität. Basierend auf den Ergebnissen der beiden ersten Phasen erfolgt bei Bedarf eine Überarbeitung des deutschsprachigen QUALIDEM.

Fazit: Insgesamt soll das Qol-Dem Projekt eine genaue Einschätzung der testtheoretischen Eigenschaften sowie einen Beitrag zur Weiterentwicklung des QUALIDEM liefern. Daneben werden die Ergebnisse zur theoretischen Weiterentwicklung des Konzeptes Lebensqualität von Menschen mit Demenz beitragen.

Schlüsselwörter: Lebensqualität, Demenz, stationäre Altenpflegeeinrichtung, psychometrische Eigenschaften, Fremdeinschätzung, Meta-Synthese, QUALIDEM


The incidence and prevalence of dementia is increasing due to changes in demographics [1]. The most common type of dementia, Alzheimer’s disease, is expected to increase from approximately 6 to 13 million affected people in Europe by 2040 [2]. In addition, estimates suggest an increase from the current prevalence of 1.2 million people in Germany to 2.5 million in the year 2060 [3]. Dementia is the primary reason why older adults are admitted to a nursing home [4]. In Germany, approximately 70% of care-dependent people with dementia live in nursing homes [3], [5]. For people with dementia, the disease results in a loss of significant roles, respect, autonomy, self-worth and competency [6]. Dementia is a progressive disease with an often insidious onset. This allows those who are affected with the disease to adapt to the situation and to manage the disease actively [7]. Because the disease is not curable, caring interventions provide support for patients who are trying to adapt to their new and changing life situation. The primary objective of care is the maintenance and promotion of quality of life (Qol) in this population [8]. Therefore, Qol has become a primary outcome in intervention studies and an indicator for the quality of care in this population [9], [10]. In addition, there is a need for dementia-specific Qol-measures [11], [12]. Thus, several dementia-specific Qol measures have been developed, which have used self-ratings, proxy ratings or observational data as information sources [12], [13]. Qol is a subjective, multi-dimensional and independent construct [14]. Therefore, self-reports from people with dementia are acknowledged as the gold standard for measuring Qol in this population [15], [16]. However, the cognitive decline among people with dementia is characterized by memory and concentration deficits and results in a decrease in decision-making and communicative abilities. Therefore, the reliability and validity of Qol self-reports has been questioned in later stages of the disease [12], and the use of proxy measures is preferred in advanced dementia and for longitudinal Qol evaluation [17]. However, proxy-rated Qol measures are associated with numerous methodological difficulties. Scores are systematically lower than self-rated Qol values [18], [19], [20], [21]. Proxy-rated Qol values from people with dementia are influenced by the burden [22], [23] and attitudes of proxy-raters [24]. Existing measurements can be distinguished based on their feasibility, psychometric properties, stage of dementia and care setting in which the application of the instrument is possible, as well as the underlying Qol definition and domains [12], [13]. These factors complicate the selection of an appropriate instrument.

The lack of theoretical clarity leads to a wide variance in the different strategies for the psychometric evaluation of these instruments, especially the evaluation of validity. Thus, different comparators and statistical methods have been used for the evaluation of the validity of dementia-specific Qol measures. These comparators include other standardized generic instruments, e.g. the EQ-5D [23], different dementia-specific measurements [25] and general ratings of the Qol of people with dementia that are made by relatives or head nurses. Mood and feelings [26], domains of challenging behavior [27], daily and social activities [27], [28], pain medication [29] as well as functional and cognitive ability are the commonly used comparators [25], [27], [28], [30]. The last two comparators might be questioned as long as there is no evidence for the assumption that a correlation, for example between cognitive impairment and Qol, is a reference for the validity of a dementia-specific Qol-measure. In contrast, pain is rarely used as a comparator, although pain is very likely to be associated with reduced Qol [31] and has a high prevalence in nursing home residents [32], [33]. Because a commonly accepted Qol definition does not exist, and standards to verify the validity of assessments as well as a validated set of comparators are lacking, it remains unclear how the validity of dementia-specific Qol-measures, either for self-rating or proxy-rating, should be appropriately investigated.


QUALIDEM is a fairly new dementia-specific Qol instrument [34]. It has been evaluated with respect to its psychometric properties with a focus on psychosocial domains [34]. The instrument is easy to administer [35] and was developed for proxy-rating of Qol throughout the entire course of dementia in nursing home residents [27]. Consequently, QUALIDEM is recommended for Qol assessment in the late stages of dementia [36] and to assess Qol longitudinally [11]. QUALIDEM was developed and validated between 2005 and 2007 by Dutch researchers. The instrument consists of two versions. Qol among people with mild to severe dementia is assessed using the 37 item-version covers the following nine domains of Qol: care relationships, positive affect, negative affect, restless tense behavior, positive self-image, social relationships, social isolation, feeling at home and having something to do. The domains positive self-image, feeling at home and having something to do cannot be assessed in people with very severe dementia. Thus, the second version consists of 18 items covering the following six domains of Qol: care relationship, positive affect, negative affect, restless tense behavior, social relationships and social isolation. The response options for all items are as follows: never, rarely, sometimes and frequently. The stages of dementia severity are classified according to the Global Deterioration Scale (GDS), which is a staging instrument indicating cognitive deterioration in dementia [37]. The scale score ranges from 1 to 7 (1: free of cognitive impairment, 2–6: very mild dementia to severe dementia, 7: very severe dementia) [37].

In 2008, the QUALIDEM was translated to German by a certified agency using forward-backward translation. The back-translated version has been verified by the questionnaire’s first author, and the German version has been subsequently revised based on his comments. An initial exploratory study demonstrates the construct validity, as measured by factor analysis, and the moderate to high internal consistency of the German version [35].

Aim of the study

The study primarily aims to investigate the reliability and further validity of the QUALIDEM in Germany, using a theoretical framework for the evaluation of validity. To achieve this aim, a further goal is the development of a dementia-specific Qol model as a result of a meta-synthesis of qualitative studies. This is an important foundation for deriving appropriate strategies for the evaluation of the validity of dementia-specific Qol measurements among people with dementia.

The specific research questions are as follows:

  • Which domains of Qol are described as relevant from the perspective of people with dementia?
  • To what extent is the scalability of the German QUALIDEM?
  • To what extent is the internal consistency of the German QUALIDEM?
  • What is the interrater reliability of the German QUALIDEM?
  • What is the intrarater reliability of the German QUALIDEM?
  • To what extent is the validity of the German QUALIDEM?


The project consists of three methodological phases with different steps (Figure 1 [Fig. 1]). The phases build on each other; thus, the results of the first phases will influence and guide the methods used in the following phases.

Theoretical phase

Referring to the first research question, a meta-synthesis of qualitative studies on Qol from the perspective of people with dementia will be performed (Review registration: PROSPERO register CRD42013005014). This synthesis of perspectives on Qol will result in a dementia-specific Qol model and guide the selection of adequate strategies for the validation of the QUALIDEM as a further step.

Search strategy

To identify all relevant published studies addressing the research question, an extensive search strategy will be used covering the databases Medline, EMBASE, CINAHL, and PsychINFO without any time limit. Search terms for all relevant expressions of dementia and Qol will be combined using a sensitive strategy from the McMaster University, Canada [38] for the identification of qualitative studies. Reference lists of included publications will be checked. Web of Science or eligible databases will be used for forward citation tracking of selected papers.

Selection of the studies and quality appraisal

Both the selection of the relevant studies and the quality appraisal of the studies will be conducted by two independent reviewers. In the case of any discrepancy, a consensus will be reached by discussion or via consultation with a third reviewer. Table 1 [Tab. 1] provides the pre-defined inclusion criteria for the study selection.

The methodological quality of the selected studies and manuscripts will be assessed using the formal appraisal criteria from the Critical Appraisal Skills Programme [39].

Data extraction and synthesis

Data extraction will be conducted by two independent reviewers using the template form of the Qualitative Assessment Review Instrument [40]. Potential discrepancies will be discussed until a consensus is achieved, if necessary with the addition of a third reviewer. The principles and procedures of grounded theory will guide the analysis of the included publications [41]. In particular, the constant comparative method will be used for the coding, identification of categories and synthesis. The possible influence of culture and care setting as well as influences over time will be considered during the synthesis. The data will be analyzed using the MAXQDA software [42].

Selection of validation strategies

The results of the meta-synthesis will be used to determine the appropriate strategies for the validation of the QUALIDEM (see also empirical phase: validity).

Empirical phase: scalability and internal consistency

To evaluate scalability and internal consistency (research questions 2 and 3), a secondary data analysis of baseline data from the following three studies will be performed: Data collected in a pre-post-test design on the evaluation of quality instruments in nursing homes (InDemA: Interdisciplinary Implementation of Quality Instruments for the Care of residents with Dementia in Nursing Homes) [43], a cluster-randomized controlled trial on the evaluation of the Serial Trial Intervention (STI-D: Serial Trial Intervention-Germany) [44], and a cross-sectional study on Dementia Care Mapping use (Leben-QD I: Strengthening Qol among people with dementia) [45].

Setting and location

Data collection for the InDemA study occurred between October and December 2008, for the STI-D study between January and March 2009, and for the Leben-QD I study between September and November 2010. The total sample consisted of approximately 630 residents with dementia from 43 German nursing homes located in the area of Frankfurt/Main (STI-D study, n=19) and in North-Rhine Westphalia (InDemA study and Leben-QD I study, n=24).


In the three primary studies, nurses with different qualifications (registered nurses and nursing assistants) completed the instrument based on a retrospective observation period of two weeks. Inclusion criteria for nurses were a close relationship to the assessed resident. A Functional Assessment Staging (FAST) [37] score ≥2 (Leben-QD I) or a Mini Mental Status Examination (MMSE) [46] score ≤24 (InDemA and STI-D) were the inclusion criteria for residents with dementia. In addition, the residents were required to have been living in the nursing home for at least 2 weeks (Leben-QD I and InDemA) or 4 weeks (STI-D). The Mini Mental Status Examination (MMSE) ranges from 1 to 30 points (≤ 24 points: mild dementia, ≤ 10 points: severe dementia) [46]. The interpretation of the FAST scale is similar to the GDS [37]. Exclusion criteria were a documented diagnosis of schizophrenia or other psychotic disorders (InDemA and STI-D). For the purpose of quality assurance, QUALIDEM administration was always initiated by external study assistants who were registered nurses and students in nursing or health care study programs. They received prior training on data collection, and a comprehensive manual for data collection was available.

Statistical methods

To examine whether the adopted Dutch subscales are present in the German version of the QUALIDEM, Mokken’s non-parametric latent trait model for uni-dimensional scaling will be used in a confirmatory manner. This non-parametric method is an improved version of the Guttman scale, which has a broad application in the social sciences [47]. Using this method, it is possible to identify homogeneous unidimensional (sub)scales based on a set of ordinal polytomous items, which allows for the reliable ranking of individuals. In addition, the choice of this technique provides the possibility of a direct comparison with the results from previous Dutch studies [11], [34]. To examine the internal consistency, Cronbach’s Alpha will be calculated for all resulting subscales. If the presumption of double monotonicity will be fulfilled, the reliability coefficient Rho will also be calculated. This coefficient is not as prone to bias as Cronbach’s alpha [48]. The Mokken scale analysis will be performed using the Mokken package for the software R [48], [49].

Empirical phase: interrater and intrarater reliability

This step aims to answer research questions 4 and 5, which result in an estimation of the interrater and intrarater reliability of QUALIDEM.

Setting and location

The data for interrater and intrarater reliability testing will be collected as a part of the baseline data collection of the Leben-QD II study (a quasi-experimental trial on Dementia Care Mapping use) [50]. This sample consists of residents of nursing homes distributed across the state North-Rhine Westphalia.

Sample size calculation

The sample size calculation is based on the recommendations of Bonett et al. [51]. They developed a method to estimate the number of subjects required for two or more raters to obtain a 95% confidence interval (CI) with desired width for any planning value of intraclass correlation coefficient (ICC). We aim to achieve ICCs similar to that obtained by Ettema et al. calculated for the different QUALIDEM subscales in their study [34]. We use the planning ICC values to obtain an interrater reliability range between 0.79 and 0.47 (37-item version) and between 0.79 and 0.55 (18-item version). With four independent raters (nurses) and a width of 0.2 for the resulting 95% (CIs), the sample size is, depending on the subscale, 34 to 106 residents with mild to severe dementia for the 37-item version and 34 to 93 residents with very severe dementia for the 18-item version of the QUALIDEM. To achieve precise results, we aimed to recruit 106 residents with mild to severe dementia and 93 residents with very severe dementia for the evaluation of interrater reliability.

Based on previous findings [34] and on a defined CI width of 0.2, the sample size calculation for the investigation of the intrarater reliability resulted in a range between 18 and 85 (37-item version) and 39 to 75 (18-item version) residents depending on the subscale. To obtain precise results for intrarater reliability, we aim to recruit 85 (37-item version) and 75 (18-item version) residents for the evaluation of intrarater reliability.


The evaluation of the interrater and intrarater reliability will also be based on proxy-ratings from nurses based on a retrospective observation period of 2 weeks. Inclusion criteria for residents with dementia will be a GDS score ≥2 and a length of stay of at least 2 weeks in the nursing home. The qualification level of the nurses (registered nurses and nursing assistants) will depend on organizational conditions and staffing levels at the time of the data collection. Inclusion criteria for nurses are as follows: a close relationship to the assessed resident and a working contract of at least 50% of the regular working hours. In addition, the nurses must be at work during most days within the last 2 weeks prior to the data collection to ensure the close relationship, which will facilitate the use of up-to-date information about the resident. For the examination of interrater reliability, four nurses from each nursing home will assess the Qol of 106 residents with mild to severe dementia and 93 residents with very severe dementia independently from each other. For intrarater reliability, one of these nurses will assess the Qol of 85 residents with mild to severe dementia and 75 residents with very severe dementia again after one week. The socio-demographic data for the nurses, e.g., age, professional qualification and work experience, will be recorded. To ensure standardized data collection, the QUALIDEM application will be initiated by external trained study assistants who are registered nurses.

Statistical methods

For the interrater and intrarater reliability, an ICC based on a two-way random effects model for absolute agreement will be calculated for each subscale of the QUALIDEM. This procedure allows the comparison of the results with previous findings from the Netherlands [34]. The interrater and intrarater reliability of every item of the QUALIDEM will be calculated using the mean of quadratic weighted Kappas. These additional analyses provide information about the reliability of the individual items within a subscale and, thus, can potentially be used to improve the reliability of a subscale.

Empirical phase: validity

In this step of the project, the sixth research question will be examined. The methods to be used are guided by the Qol model based on the previous meta-synthesis (theoretical phase).

Setting and location

The validity of the QUALIDEM will be examined in the nine nursing homes that are participating in the Leben-QD II project.


Our meta-synthesis will identify domains of Qol. Consequently, relevant comparators and hypotheses can be derived for the investigation of the validity of the QUALIDEM. In addition to the identified constructs, further comparators will be assessed, allowing for a comparison of study results against other validation studies of Qol measurements. These comparators include mood and feelings [27], [28], [30], domains of challenging behavior [27], and daily and social activities [26], [28].

The commonly applied Qol measurements, the Quality of Life-Alzheimer Disease (QOL-AD) [52] (self- and proxy-assessment) and the Dementia Quality of Life Instrument (DQol) [15] (self-assessment), will also be used as comparators for the evaluation of validity. Both instruments are recommended by a European consensus paper for the self-assessment of dementia-specific Qol [36].

Furthermore, possible pain of people with dementia will be assessed as comparator. There have been very few studies that have compared Qol among people with dementia and pain, as an expression of the validity of a Qol instrument. We identified only one study, which suggested the lack of a significant correlation between measured pain and Qol among people with dementia [53]. This result might be due to the lack of a sensitive assessment of pain among people with dementia. Therefore, a correlation between Qol and pain as an expression of the validity of a Qol instrument seems to be theoretically well justified.

Statistical methods

Descriptive statistics will be calculated for the sample characteristics. Bivariate statistics will be used to study the correlation between the scalable and reliable QUALIDEM subscales and the defined comparators.

Final phase: summarizing evaluation

In the final phase, all results from the previous project steps will be summarized to offer conclusions regarding the content and the psychometric quality of the German version of the QUALIDEM. Based on previous results, it may be necessary that adaptations of the content or the operationalization of individual items or subscales have to be performed.


The psychometric properties of a standardized measurement are context-specific attributes. An instrument that has demonstrated satisfactory measurement properties in one population is not necessarily appropriate for use in other populations [54]. Moreover, the highly subjective construct of Qol underlies culture specific influences in the expression of Qol domains. The intensive psychometric evaluation of the German version of the QUALIDEM will result in a comprehensive statement of the reliability, validity and content quality of the use of the instrument during clinical trials in Germany. The samples for the different phases of the study are heterogeneous with respect to the course of dementia. This is the primary requirement for testing the instrument [11]. The results will be important for the comparison of Qol as a primary outcome in intervention studies for people with dementia.

The theoretical phase of the study is expected to provide an important contribution to the theoretical discussion of the Qol concept. The synthesis of qualitative studies on the perspectives of people with dementia about their Qol results in a new dementia-specific Qol model. The stepwise approach of the study allows for a theoretical justification of the methods in the validation step, and the summaries offer a broad and careful evaluation of the content and the psychometric properties of the German version of the QUALIDEM.



The study protocol of the STI-D study was approved by the ethics committee of the Charité-Universitätsmedizin, Berlin. The ethics committee of the German Society of Nursing Science approved the study protocol of the InDemA study and the Leben-QD study (part I and II). Approval for the Leben-QD study covers the empirical steps of the Qol-Dem project.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

MND, MH, GM and SB designed the study. MND drafted the manuscript. MH, GM, OD and SB helped to draft the manuscript and supervise the study. All authors read and approved the final manuscript.


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