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Item distribution, scalability and internal
consistency of the QUALIDEM quality of life
assessment for patients with dementia in acute
hospital settings
Daniel Lüdecke ( d.luedecke@uke.de )
University Medical Center Hamburg-Eppendorf
Martin Nikolaus Dichter
University of Cologne, University of Cologne Medical Faculty and University Hospital Cologne
Stefan Nickel
University Medical Center Hamburg-Eppendorf
Christopher Kofahl
University Medical Center Hamburg-Eppendorf
Research Article
Keywords: QUALIDEM, quality of life, patients with dementia, hospitals, validation
Posted Date: March 31st, 2022
DOI: https://doi.org/10.21203/rs.3.rs-1506571/v1
License: This work is licensed under a Creative Commons Attribution 4.0 International License.
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Abstract
Background
Quality of life (QoL) of people with dementia (PwD) is an important indicator of quality of care. Studying
the impact of acute hospital settings on PwD’s QoL requires assessment instruments that consider
environmental factors. Until now, dementia-specic QoL instruments have not demonstrated their
feasibility in acute hospitals. Therefore, validated instruments to study QoL-outcomes of patients with
dementia in hospitals are needed.
Methods
Data stem from a study that analysed the impact of a special care concept in acute hospitals for patients
with dementia on their QoL. Total sample size consisted of N = 526 patients. QoL was assessed with the
QUALIDEM. This instrument consists of nine subscales that can be applied to people with mild to severe
dementia (N = 344), while six of the nine subscales are applicable for people with very severe dementia
(N = 182). Scalability and internal consistency were tested with Mokken scale analysis.
Results
For people with mild to severe dementia, seven out of nine subscales were scalable (0.31 ≤ H ≤ 0.75).
Five of these seven subscales were also internally consistent (ρ ≥ 0.69), while two had insucient
reliability scores (ρ = 0.53 and 0.52). The remaining two (
positive self-image
,
feeling at home
) subscales
had rather low scalability (H = 0.17/0.16) and reliability scores (ρ = 0.35/0.36). For people with very severe
dementia, all six subscales were scalable (0.34 ≤ H ≤ 0.71). Five out of six showed acceptable internal
consistency (ρ = 0.65 to 0.91). Only the item s
ocial relations
had insucient reliability (ρ = 0.55).
Conclusions
In comparison with a previous evaluation of the QUALIDEM in a long-term care setting, the application in
a hospital setting leads to very similar, acceptable results for people with mild to severe dementia. For
people with very severe dementia, the QUALIDEM seems to t even better in a hospital context. Results
suggest either a revision of unsatisfactory items or a general reduction to six items for the QUALIDEM, for
all PwD. In general, the QUALIDEM can be recommended as instrument to assess the QoL for PwD in the
context of hospital research. Additionally, an investigation of the inter-rater reliability is recommended.
Background
Acute hospitals face the challenge of changes in demographic and clinical characteristics of people who
need acute health care, which leads to an increased prevalence of people with dementia (PwD) [1, 2].
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According to current studies and systematic reviews, there are no precise numbers on the prevalence of
cognitive impairment in patients in hospitals. Most studies, however, indicate that a proportion of approx.
40% inpatients has at least mild cognitive impairments or diagnosed dementia [3].
Many hospitals and their personnels are insuciently prepared for those people with cognitive
impairments, especially in acute care units predominantly focussing on somatic diseases [4]. This results
in an increased likelihood of complications during the hospital stay and of post-operative complications,
which in turn affects the quality of life (QoL) of PwD [5–7]. However, QoL is an important indicator of
quality of care and a major dimension when assessing patient reported outcomes, particularly in older
people as global outcome measure for interventions [8, 9].
Therefore, psychometrically validated instruments to measure QoL of PwD in hospital contexts are
strongly needed. A recent systematic review and meta-regression analysis by Li et al. reveals a number of
generic instruments such as the EuroQol ve-dimension questionnaire (EQ-5D) and dementia-specic
instruments such as the DEMQOL-U [10]. Most instruments, however, are not feasible to assess QoL in
acute hospitals. Usually, QoL instruments for PwD were only validated in nursing home care settings.
This holds true for the recently developed QUALIDEM instrument, too [11, 12]. QUALIDEM is based on the
adaptation-coping model [13] and denes dementia-specic QoL as a multidimensional assessment of
the individual person-environment system in terms of adaptation to the perceived consequences of
dementia [11]. This means that the dementia-specic QoL is the result of a successful or unsuccessful
adaptation of the PvD to the physical, psychological and social consequences of the dementia syndrome.
Against this background, the aim of this paper is to investigate whether the item distribution, scalability
and internal consistency of the subscales of the German version of the QUALIDEM instrument can be
replicated in a hospital context, to draw conclusions about the applicability of the QUALIDEM in hospital
research with PwD. However, proxy ratings with an instrument as QUALIDEM are accompanied by
methodological challenges, and the results are systematically lower than those for self-rated QoL [14].
Methods
Design
Primary data was collected in a study called “DAVID” (German acronym for Diagnostics, Acute therapy,
Validation at an Internal medicine ward for patients with Dementia) that compared the quality of care for
patients with dementia within an internal medicine unit with a specialised dementia care concept as
opposed to regular care in acute hospitals. The study was designed as a cross-sectional case-control-
study, including two internal medicine wards in two hospitals located in Hamburg, Germany [15].
Prior to the study, a study protocol was developed and submitted to the ethical committee of the medical
association of Hamburg. The ethical committee approved the proposal and attested that the study
conforms to ethical and legal requirements (approval code PV5102). Study participants were not able to
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give their informed consent due to their cognitive impairments. However, as data mostly derived from the
hospitals’ regular documentation, and as data was completely anonymous, the ethics committee waived
the need of an informed consent.
Intervention Group
The special care ward “DAVID” is an internal medicine ward in the Protestant Hospital Alsterdorf, a not-
for-prot organization, and has 14 beds. During the 12 months of data collection, 349 patients were
treated. The ward employed nine care workers as nursing staff. Key components of the special care
concept are a specic architectonical design, including a homelike lounge or a specic colouring of doors
and walls; doctors, nurses and service staff are trained in coping with challenging behaviour and other
dementia related issues, like basal stimulation or validation therapy; mobile devices for diagnostics, to
perform as many treatments as possible in the different rooms of the special care ward; involvement of
relatives into assessment, care and discharge planning; and regular therapeutic offers like occupational
or speech therapy, and social offers like music, playing or spending more time than usual to care for the
patients.
Control Group
The regular care ward is part of a larger private-company hospital with emergency hospitalisation. It has
80 beds and during the 12 months of data collection, about 3,500 patients were treated in this internal
medicine ward. Twenty-six employees worked as care staff in this ward. Trainees sometimes supported
the care team. The regular care ward had no specic care concept for dementia patients. The care staff
was not particularly trained in dementia topics.
Data collection and participants
An assessment questionnaire was developed to obtain data from PwD. Study nurses were trained in
using this assessment questionnaire and then conducted the data collection in both hospitals. The
assessment questionnaire comprised items on different domains like QoL, functional limitations,
cognitive status, comorbidities, agitation or challenging behaviour. Participants were observed for about
one week (depending on the length of stay). The study nurses then rated the participants’ outcomes for
these domains. Two study nurses were responsible for data collection in the special care ward and one
study nurse for the data collection in the regular care ward. Data was collected from June 2016 to July
2017. People with dementia were included when they showed at least mild cognitive impairments or
memory problems. A short dementia screening using the Salzburg dementia test prediction (SDTP) [16]
was carried out by the study nurse to assess the severity of dementia of patients who had no claried
dementia diagnosis, and to identify further patients who qualify for the study. Patients were excluded
when they were not responsive or completely conned to bed due to severe health-related dependency. As
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both care wards had no particular selection criteria for patients such as age, mobility, or the main
diagnosis that lead to hospital admission, no further exclusion criteria for the study were dened. The
total sample size for the present analysis consists of N = 526 people with dementia (special care ward: n
= 333; regular care ward: n = 193).
Measurements
For the description of the sample, information on age, gender, length of stay, functional limitations and
quality of life were used. Functional limitations in daily living were assessed with the Barthel-Index [17].
This score ranges from 0 (completely dependent) to 100 points (no basic functional limitations).
The QUALIDEM (Version 1) [11, 12] was used to assess the QoL in PwD. QUALIDEM for people with mild
to severe dementia comprises 37 items reecting nine different subdomains of QoL: “care relationship” (7
items, 0–21 points), “positive affect” (6 items, 0–18 points), “negative affect” (3 items, 0–9 points),
“restless and tense behaviour” (3 items, 0–9 points), “positive self-image” (3 items, 0–9 points), “social
relations” (6 items, 0–18 points), “social isolation” (3 items, 0–9 points), “feeling at home” (4 items, 0–12
points) and “have something to do” (2 items, 0–6 points). For individuals with very severe dementia, only
six of the nine subscales apply (with a total of 18 items), whereby the dimensions “positive self-image”,
“feeling at home” and “have something to do” were omitted. For each subscale, higher values indicate
higher QoL. In the QUALIDEM questionnaire, not all of the 37 items were coded in the same direction.
That is, for some items higher values mean a better QoL, while other items were coded so that lower
values indicate better QoL. Thus, where necessary, items were recoded so higher values always indicate
higher QoL. In the original version of the QUALIDEM, which was developed for long-term care settings,
some items used the wording “residents”. In the present study, the term “patients” was used, which is
more appropriate in a hospital setting.
The Mini Mental Status Examination test [18] was used to assess the severity of dementia. The score
ranges from 0 (very strong cognitive impairments) to 30 (very mild or no cognitive impairments) points. A
cut-off score of MMSE < 10 indicates very severe dementia in patients.
Statistical analysis
The descriptions of the participants, the missing data, and the item distributions are based on descriptive
statistics. Since the QUALIDEM subscales differ in the number of items contributing to each subscale, we
normalized the subscale scores (for the gures only), so each subscale in the gures ranges from 0 to 1.
This allows a more intuitive comparison of QUALIDEM subscales because they no longer have different
ranges.
The item distribution for all QUALIDEM items is reported and the diculty for each item is calculated to
indicate oor (item diculty < 0.2) or ceiling (item diculty > 0.8) effects, which means items have poor
discrimination if these thresholds are exceeded [19].
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Scalability and internal consistency of the QUALIDEM subscales were analysed with the conrmatory
Mokken scale analysis (MSA) [20–22], which is a scaling procedure for both dichotomous and ordinal
polytomous items. It can be used to assess whether a number of items measure the same underlying
concept of a scale. MSA has been widely used in QoL research and is the preferred method for
instruments like the QUALIDEM that consist of ordinal data [12, 23, 24]. The scalability of scales is
measured by Loevinger's coecient H, in short just “H”. It indicates the internal correlation of each
subscale. Mokken [20] proposed the following rules of thumb for this coecient: A scale is considered
weak if 0.3 ≤ H < 0.4, moderate if 0.4 ≤ H < 0.5, and strong if H ≥ 0.5. If H is lower than 0.3, an item or
scale is considered “not scalable”, which means items are unrelated, thus not reecting the underlying
concept of a scale. The correlation between a single item to the remaining items of a scale is expressed
by the value “Hi”, which should be non-negative to full the assumptions of the MSA, and should be
higher than 0.3 to show at least moderate discrimination power and thereby being useful for the scale
[24]. The criterion of the MSA (“crit”, [25]) was used to check monotonicity assumptions. This assumption
relates to the probability of a particular item level or the correct answer is a monotonically non-decreasing
function of the latent trait of that item [26].
Finally, the Molenaar Sijtsma statistic (“rho”, ρ) as well as Cronbach’s α were calculated as reliability
measures for the internal consistency of scales [27, 28], the latter mainly for comparison to other study
results. For both ρ and α, a value smaller than 0.6 indicate insucient internal consistency of a scale,
while values above 0.7 are acceptable or satisfying. Scales with ρ or α between 0.6 and 0.7 are sucient,
but questionable.
For the present MSA, missing values were imputed using the suggested two-way imputation [29, 30]. In a
second step, missing data were imputed using the multivariate imputation by chained equations method
[31], in order to compare how different imputation methods affect the results of the MSA (these results
are shown in the Additional le 1, table A1).
All analyses were performed using the R statistical package [32] with the R packages
mokken
[33],
mice
[31] and
sjPlot
[34]. Figures were created using
ggplot2
[35]. Analyses were carried out for the two
subgroups “mild to severe dementia” (MMSE > = 10) and “very severe dementia” (MMSE < 10) separately.
Results
Characteristics of the sample
Table 1 shows the sample characteristics. The sample consisted of 526 patients, − 344 people with mild
to severe dementia, and 182 with very severe dementia. 60.6% of the participants were female. The mean
age was 80.5 years and the average length of hospital stay was about 9.4 days. These characteristics are
similar for both sub-groups (mild to severe and very severe dementia).
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Table 1
Characteristics of the sample, shown are proportions of sample (%), or mean and standard deviation (in
parenthesis)
Characteristic Mild to severe
dementia Very severe dementia Total
Proportion Female, % 59.3 63.2 60.6
Mean Age (SD) 81.5 (9.5) 78.7 (12.1) 80.5 (10.6)
Mean Barthel-Index (SD) 45.9 (28.5) 19.4 (24.4) 36.7 (29.9)
Mean Length of Stay (in Days) 9.2 (5.4) 9.7 (7.8) 9.4 (6.3)
Mean QUALIDEM Total Score 51.2 (16.0) 40.1 (16.5) 47.3 (17.0)
Mean QUALIDEM Subscale
Scores*
A) Care Relationship 16.0 (4.5) 5.1 (2.7)
B) Positive Affect 11.0 (5.1) 5.2 (3.6)
C) Negative Affect 6.9 (1.8) 4.5 (1.5)
D) Restless tense behaviour 7.2 (2.2) 6.5 (2.7)
E) Positive self-image 7.5 (1.6) NA
F) Social relations 9.8 (3.6) 4.5 (2.1)
G) Social Isolation 6.4 (2.2) 6.2 (2.3)
H) Feeling at home 7.4 (2.1) NA
I) Having something to do 2.2 (1.8) NA
N 344 182 526
Barthel-Index: 0-100 (higher = better functioning); QUALIDEM: 0-100 (higher = better QoL); * Mean
values are not directly comparable because number of items per subscale differ between patients
with mild to severe and patients with very severe dementia
The average Barthel-Index in the sample was 36.7, but comparably higher for people with mild to severe
dementia (45.9) as opposed to those people with very severe dementia (19.4). According to the QoL,
people with mild to severe dementia had a mean QUALIDEM-score of 51.2, while the group of people with
severe dementia had a mean score of 40.1. Looking at the normalized scores of the QUALIDEM
subscales for people with mild to severe dementia in gure 1, we nd higher QoL for the “care
relationship”, “restless behaviour”, “positive self-image” and “social isolation”, while especially the domain
of “having something to do” is associated with the lowest QoL score. People with very severe dementia
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show higher QoL scores for “negative affect” and “restless behaviour”, while “positive affect” and “social
relations” are those domains with the lowest QoL scores (gure 2).
Fig. 1: Distribution of QUALIDEM Scores from each subscale for patients with mild to severe dementia
(n=344)
Fig. 2: Distribution of QUALIDEM Scores from each subscale for patients with very severe dementia
(n=182)
Missing Value Analysis
Of the 37 QUALIDEM items for the group of people with mild to severe dementia, 612 out of 12,728
responses were missing (4.8%). For the people with very severe dementia, 350 out of 3,276 responses of
the 18 QUALIDEM items (10.7%) were missing.
Item distribution
Table2 shows the distribution of items of the QUALIDEM for people with mild to severe dementia. The
distribution of items varies between the different subscales of the QUALIDEM. Eleven items out of six
subscales (“care relationship”, “negative affect”, “restless tense behaviour”, “positive self-image”, “social
isolation” or “feeling at home”) showed a ceiling effect with a left-skewed distribution from “often” to
“never”. The response category for these items was in most cases “never” (from about 45–75%, except
for two items “cries” and “is rejected by other patients”, which have a proportion of 35.8% and 37.8%,
respectively). 11 items show ceiling effects, while two items show oor effects. Subscales where at least
half of the items have ceiling or oor effects are “negative affect”, “positive self-image” and “feeling at
home”. The items of the subscale “positive affect” showed a similar distribution with a peak at the
response category “rarely”, so the ceiling effect was less evident. The other scales showed no consistent
pattern across items.
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Table 2
Item distribution (range 0–3) of nine QUALIDEM subscales for people with mild to severe dementia,
including missing values and mean/SD (n = 344)
Item
Nr. Subscale (Item) 0 1 2 3 Missing
values Mean
(SD) Item
Diculty
A Care
Relationship
4. Rejects help
from nursing
assistants a
20
(5.8%) 40
(11.6%) 48
(14.0%) 217
(63.1%) 19
(5.5%) 2.4
(0.9) 0.81
7. Is angry a33
(9.6%) 70
(20.3%) 82
(23.8%) 157
(45.6%) 2
(0.6%) 2.1
(1.0) 0.69
14. Has conicts
with nursing
assistants a
29
(8.4%) 66
(19.2%) 76
(22.1%) 170
(49.4%) 3
(0.9%) 2.1
(1.0) 0.71
17. Accuses others a26
(7.6%) 55
(16.0%) 61
(17.7%) 183
(53.2%) 19
(5.5%) 2.2
(1.0) 0.74
24. Appreciates help
he or she
receives b
29
(8.4%) 57
(16.6%) 90
(26.2%) 162
(47.1%) 6
(1.7%) 2.1
(1.0) 0.71
31. Accepts help b11
(3.2%) 33
(9.6%) 90
(26.2%) 194
(56.4%) 16
(4.7%) 2.4
(0.8) 0.81
33. Criticizes the
daily routine a
16
(4.7%) 38
(11.0%) 60
(17.4%) 225
(65.4%) 5
(1.5%) 2.5
(0.9) 0.82
B Positive Affect
1. Is cheerful b52
(15.1%) 78
(22.7%) 102
(29.7%) 98
(28.5%) 14
(4.1%) 1.7
(1.0) 0.58
5. Radiates
satisfaction b
37
(10.8%) 72
(20.9%) 124
(36.0%) 105
(30.5%) 6
(1.7%) 1.9
(1.0) 0.63
8. Is capable of
enjoying things
in daily life b
25
(7.3%) 81
(23.5%) 134
(39.0%) 100
(29.1%) 4
(1.2%) 1.9
(0.9) 0.64
10. Is in a good
mood b
39
(11.3%) 84
(24.4%) 124
(36.0%) 94
(27.3%) 3
(0.9%) 1.8
(1.0) 0.60
21. Has a smile
around the
mouth b
38
(11.0%) 85
(24.7%) 109
(31.7%) 98
(28.5%) 14
(4.1%) 1.8
(1.0) 0.60
a = coding of items is 0 = often, 1 = sometimes, 2 = rarely, 3 = never; b = coding of items is 0 = never, 1 =
rarely, 2 = sometimes, 3 = often
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Item
Nr. Subscale (Item) 0 1 2 3 Missing
values Mean
(SD) Item
Diculty
40. Mood can be
inuenced in
positive sense b
30
(8.7%) 97
(28.2%) 105
(30.5%) 109
(31.7%) 3
(0.9%) 1.9
(1.0) 0.62
C Negative Affect
6. Makes an
anxious
impression a
16
(4.7%) 16
(4.7%) 40
(11.6%) 255
(74.1%) 17
(4.9%) 2.6
(0.8) 0.88
11. Is sad a8
(2.3%) 18
(5.2%) 50
(14.5%) 248
(72.1%) 20
(5.8%) 2.7
(0.7) 0.89
23. Cries a82
(23.8%) 69
(20.1%) 67
(19.5%) 123
(35.8%) 3
(0.9%) 1.7
(1.2) 0.56
D Restless tense
behaviour
2. Makes restless
movements a
23
(6.7%) 50
(14.5%) 69
(20.1%) 196
(57.0%) 6
(1.7%) 2.3
(1.0) 0.77
19. Is restless a13
(3.8%) 20
(5.8%) 51
(14.8%) 258
(75.0%) 2
(0.6%) 2.6
(0.8) 0.87
22. Has tense body
language a
27
(7.8%) 44
(12.8%) 76
(22.1%) 182
(52.9%) 15
(4.4%) 2.3
(1.0) 0.75
E Positive self-
image
27. Indicates he or
she would like
more help a
7
(2.0%) 21
(6.1%) 55
(16.0%) 243
(70.6%) 18
(5.2%) 2.6
(0.7) 0.88
35. Indicates not
being able to do
anything a
13
(3.8%) 50
(14.5%) 90
(26.2%) 173
(50.3%) 18
(5.2%) 2.3
(0.9) 0.77
37. Indicates feeling
worthless a
19
(5.5%) 23
(6.7%) 27
(7.8%) 251
(73.0%) 24
(7.0%) 2.6
(0.9) 0.86
F Social relations
3. Has contact
with other
patients b
68
(19.8%) 95
(27.6%) 91
(26.5%) 68
(19.8%) 22
(6.4%) 1.5
(1.0) 0.50
a = coding of items is 0 = often, 1 = sometimes, 2 = rarely, 3 = never; b = coding of items is 0 = never, 1 =
rarely, 2 = sometimes, 3 = often
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Item
Nr. Subscale (Item) 0 1 2 3 Missing
values Mean
(SD) Item
Diculty
12. Responds
positively when
approached b
6
(1.7%) 39
(11.3%) 110
(32.0%) 185
(53.8%) 4
(1.2%) 2.4
(0.8) 0.80
18. Takes care of
other patients b
233
(67.7%) 34
(9.9%) 13
(3.8%) 16
(4.7%) 48
(14.0%) 0.4
(0.8) 0.12
25. Cuts
himself/herself
off from
environment a
30
(8.7%) 59
(17.2%) 60
(17.4%) 179
(52.0%) 16
(4.7%) 2.2
(1.0) 0.73
29. Is on friendly
terms with one
or more patients
b
135
(39.2%) 60
(17.4%) 65
(18.9%) 56
(16.3%) 28
(8.1%) 1.1
(1.2) 0.38
34. Feels at ease in
the company of
others a
37
(10.8%) 45
(13.1%) 32
(9.3%) 228
(66.3%) 2
(0.6%) 2.3
(1.1) 0.77
G Social Isolation
16. Is rejected by
other patients a
81
(23.5%) 53
(15.4%) 76
(22.1%) 130
(37.8%) 4
(1.2%) 1.8
(1.2) 0.58
20. Openly rejects
contact with
others a
17
(4.9%) 23
(6.7%) 48
(14.0%) 241
(70.1%) 15
(4.4%) 2.6
(0.8) 0.85
32. Calls out a39
(11.3%) 66
(19.2%) 64
(18.6%) 173
(50.3%) 2
(0.6%) 2.1
(1.1) 0.69
H Feeling at home
13. Indicates that he
or she is bored a
19
(5.5%) 26
(7.6%) 45
(13.1%) 235
(68.3%) 19
(5.5%) 2.5
(0.9) 0.84
28. Indicates feeling
locked up a
2
(0.6%) 20
(5.8%) 55
(16.0%) 237
(68.9%) 30
(8.7%) 2.7
(0.6) 0.89
36. Feels at home
on the ward b
222
(64.5%) 36
(10.5%) 41
(11.9%) 20
(5.8%) 25
(7.3%) 0.6
(0.9) 0.19
39. Wants to get off
the ward a
75
(21.8%) 78
(22.7%) 51
(14.8%) 120
(34.9%) 20
(5.8%) 1.7
(1.2) 0.59
a = coding of items is 0 = often, 1 = sometimes, 2 = rarely, 3 = never; b = coding of items is 0 = never, 1 =
rarely, 2 = sometimes, 3 = often
Page 12/28
Item
Nr. Subscale (Item) 0 1 2 3 Missing
values Mean
(SD) Item
Diculty
I Having
something to do
26. Finds things to
do without help
from others b
87
(25.3%) 83
(24.1%) 93
(27.0%) 65
(18.9%) 16
(4.7%) 1.4
(1.1) 0.47
38. Enjoys helping
with chores on
the ward b
145
(42.2%) 31
(9.0%) 28
(8.1%) 16
(4.7%) 124
(36.0%) 0.6
(1.0) 0.20
a = coding of items is 0 = often, 1 = sometimes, 2 = rarely, 3 = never; b = coding of items is 0 = never, 1 =
rarely, 2 = sometimes, 3 = often
The distributions of the QUALIDEM items for people with very severe dementia (Table 3) show
comparable patterns as in Table2, however, with a less pronounced proportion of the response category
“never”. Only two items show ceiling effects (“makes an anxious impression” and “openly rejects contact
with others”), while we found no oor effects in the six subscales of the QUALIDEM items for people with
very severe dementia.
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Table 3
Item distribution (range 0–3) of six QUALIDEM subscales for people with very severe dementia, including
missing values and mean/SD (n = 182)
Item
Nr. Subscale (Item) 0 1 2 3 Missing
values Mean
(SD) Item
Diculty
A Care
Relationship
7. Is angry a26
(14.3%) 29
(15.9%) 41
(22.5%) 80
(44.0%) 6
(3.3%) 2.0
(1.1) 0.66
14. Has conicts
with nursing
assistants a
30
(16.5%) 42
(23.1%) 33
(18.1%) 71
(39.0%) 6
(3.3%) 1.8
(1.1) 0.61
31. Accepts help b63
(34.6%) 43
(23.6%) 37
(20.3%) 32
(17.6%) 7
(3.8%) 1.2
(1.1) 0.41
B Positive Affect
5. Radiates
satisfaction b
39
(21.4%) 57
(31.3%) 50
(27.5%) 30
(16.5%) 6
(3.3%) 1.4
(1.0) 0.47
8. Is capable of
enjoying things
in daily life b
48
(26.4%) 49
(26.9%) 61
(33.5%) 18
(9.9%) 6
(3.3%) 1.3
(1.0) 0.43
21. Has a smile
around the
mouth b
53
(29.1%) 46
(25.3%) 48
(26.4%) 29
(15.9%) 6
(3.3%) 1.3
(1.1) 0.43
40. Mood can be
inuenced in
positive sense b
50
(27.5%) 49
(26.9%) 51
(28.0%) 25
(13.7%) 7
(3.8%) 1.3
(1.0) 0.43
C Negative Affect
6. Makes an
anxious
impression a
4
(2.2%) 4
(2.2%) 10
(5.5%) 101
(55.5%) 63
(34.6%) 2.7
(0.7) 0.92
23. Cries a55
(30.2%) 30
(16.5%) 17
(9.3%) 72
(39.6%) 8
(4.4%) 1.6
(1.3) 0.54
D Restless tense
behaviour
2. Makes restless
movements a
26
(14.3%) 38
(20.9%) 33
(18.1%) 79
(43.4%) 6
(3.3%) 1.9
(1.1) 0.65
19. Is restless a18
(9.9%) 16
(8.8%) 21
(11.5%) 123
(67.6%) 4
(2.2%) 2.4
(1.0) 0.80
Page 14/28
Item
Nr. Subscale (Item) 0 1 2 3 Missing
values Mean
(SD) Item
Diculty
22. Has tense body
language a
11
(6.0%) 26
(14.3%) 21
(11.5%) 62
(34.1%) 62
(34.1%) 2.1
(1.0) 0.71
F Social relations
3. Has contact
with other
patients b
98
(53.8%) 36
(19.8%) 22
(12.1%) 6
(3.3%) 20
(11.0%) 0.6
(0.9) 0.20
12. Responds
positively when
approached b
23
(12.6%) 38
(20.9%) 67
(36.8%) 50
(27.5%) 4
(2.2%) 1.8
(1.0) 0.60
25. Cuts
himself/herself
off from
environment a
22
(12.1%) 29
(15.9%) 15
(8.2%) 55
(30.2%) 61
(33.5%) 1.9
(1.2) 0.62
G Social Isolation
16. Is rejected by
other patients a
57
(31.3%) 22
(12.1%) 23
(12.6%) 73
(40.1%) 7
(3.8%) 1.6
(1.3) 0.55
20. Openly rejects
contact with
others a
9
(4.9%) 7
(3.8%) 13
(7.1%) 90
(49.5%) 63
(34.6%) 2.5
(0.9) 0.85
32. Calls out a49
(26.9%) 36
(19.8%) 17
(9.3%) 72
(39.6%) 8
(4.4%) 1.6
(1.3) 0.55
Scalability
Table4 shows the results from the MSA from the QUALIDEM for patients with mild to severe dementia.
Three of the nine subscales show strong scalability (“positive affect”, H = 0.77; “restless tense behaviour”,
H = 0.55; “having something to do”, H = 0.56). The subscales “care relationship” and “social relations”
have moderate scalability (H = 0.43 and H = 0.47 respectively). Most of their items were also scalable,
with exception of “rejects help from nursing assistants” (H = 0.24) and “feels at ease in the company of
others” (H = 0.28). “Negative affect” (H = 0.31) and “social isolation” (H = 0.32) show weak scalability. The
items “is sad” (H = 0.26) and “is rejected by other patients” (H = 0.28) are not scalable. The subscales
“positive self-image” (H = 0.17) and “feeling at home” (H = 0.16) were not scalable.
Page 15/28
Table 4
Scalability and internal consistency from nine QUALIDEM subscales for people with mild to severe
dementia (n = 344), 5% of all items have missing values (612 out of 12,728 data points from items are
missing)
QUALIDEM DAVID Dichter et al. [30] (Total) Arons et al.
[31] (2017)
Item
Nr. Subscale (Item) Scale-
H
(Item
Hi)
ρCronbach’s
α
Scale-
H
(Item
Hi)
ρCronbach’s
α
Scale-
H
(Item
Hi)
Ρ
A Care
Relationship .43 .82 .82 .42 .81 .81 .45 .80
4. Rejects help
from nursing
assistants
.24 .48 .47
7. Is angry .51 .49 .51
14. Has conicts
with nursing
assistants
.51 .52 .56
17. Accuses others .33 .32 .41
24. Appreciates help
he or she
receives
.47 .39 .30
31. Accepts help .42 .43 .36
33. Criticizes the
daily routine .51 .31 .44
B Positive Affect .77 .95 .94 .65 .91 .90 .65 .90
1. Is cheerful .80 .67 .66
5. Radiates
satisfaction .78 .69 .67
8. Is capable of
enjoying things
in daily life
.73 .62 .64
10. Is in a good
mood .81 .71 .72
21. Has a smile
around the
mouth
.78 .66 .66
Item numbers in tables correspond to those in Dichter et al. and Arons et al. to make comparison
easier.
Page 16/28
QUALIDEM DAVID Dichter et al. [30] (Total) Arons et al.
[31] (2017)
40. Mood can be
inuenced in
positive sense
.70 .52 .54
C Negative Affect .31 .48 .45 .53 .73 .72 .62 .80
6. Makes an
anxious
impression
.33 .49 .55
11. Is sad .26 .59 .65
23. Cries .33 .52 .65
D Restless tense
behaviour .55 .76 .74 .45 .69 .68 .36 .61
2. Makes restless
movements .53 .51 .41
19. Is restless .53 .51 .35
22. Has tense body
language .58 .32 .32
E Positive self-
image .17 .35 .34 .42 .67 .67 .64 .83
27. Indicates he or
she would like
more help
.12 .36 .64
35. Indicates not
being able to do
anything
.17 .50 .62
37. Indicates feeling
worthless .22 .41 .66
F Social relations .47 .79 .76 .43 .77 .73 .30 .65
3. Has contact with
other patients .47 .47 .40
12. Responds
positively when
approached
.46 .44 .34
18. Takes care of
other patients .67 .42 .24
Item numbers in tables correspond to those in Dichter et al. and Arons et al. to make comparison
easier.
Page 17/28
QUALIDEM DAVID Dichter et al. [30] (Total) Arons et al.
[31] (2017)
25. Cuts
himself/herself
off from
environment
.45 .33 .15
29. Is on friendly
terms with one
or more patients
.55 .45 .37
34. Feels at ease in
the company of
others
.28 .48 .38
G Social Isolation .32 .52 .52 .28 .53 .52 .44 .69
16. Is rejected by
other patients .28 .35 .46
20. Openly rejects
contact with
others
.36 .29 .45
32. Calls out .32 .21 .39
H Feeling at home .16 .36 .29 .31 .62 .61 .51 .77
13. Indicates that he
or she is bored .09 .26 .52
28. Indicates feeling
locked up .11 .34 .62
36. Feels at home
on the ward .12 .30 .20
39. Wants to get off
the ward .28 .34 .58
I Having
something to do .56 .69 .64 .18 .23 .24 .39 .53
26. Finds things to
do without help
from others
.56 .18 .39
38. Enjoys helping
with chores on
the ward
.56 .18 .39
Item numbers in tables correspond to those in Dichter et al. and Arons et al. to make comparison
easier.
Page 18/28
The MSA for the group of people with very severe dementia is shown in Table5. All six subscales were
scalable (0.34 ≤ H ≤ 0.71). The scalability could be considered as weak for “social relations”, moderate
for “social isolation” and strong for the remaining four subscales.
Page 19/28
Table 5
Scalability and internal consistency from six QUALIDEM subscales for people with very severe dementia
(n = 182), 11% of all items have missing values (350 out of 3,276 data points from items are missing)
QUALIDEM DAVID Dichter et al. [30] (Total) Arons et al.
[31] (2017)
Item
Nr. Subscale (Item) Scale-
H
(Item
Hi)
ρCronbach’s
α
Scale-
H
(Item
Hi)
ρCronbach’s
α
Scale-
H
(Item
Hi)
ρ
A Care
Relationship .50 .74 .70 .47 .73 .67 .43 .79
7. Is angry .55 .54 .53
14. Has conicts
with nursing
assistants
.58 .54 .56
31. Accepts help .36 .35 .41
B Positive Affect .71 .91 .90 .65 .86 .85 .65 .90
5. Radiates
satisfaction .72 .70 .66
8. Is capable of
enjoying things
in daily life
.71 .64 .64
21. Has a smile
around the
mouth
.75 .65 .68
40. Mood can be
inuenced in
positive sense
.67 .59 .61
C Negative Affect .65 .69 .62 .36 .50 .47 .61 .77
6. Makes an
anxious
impression
.64 .36 .51
23. Cries .64 .36 .65
D Restless tense
behaviour .65 .83 .80 .37 .59 .62 .38 .63
2. Makes restless
movements .60 .47 .48
19. Is restless .61 .45 .43
Page 20/28
QUALIDEM DAVID Dichter et al. [30] (Total) Arons et al.
[31] (2017)
22. Has tense body
language .72 .18 .24
F Social relations .34 .55 .53 .33 .53 .52 .34 .60
3. Has contact with
other patients .27 .36 .38
12. Responds
positively when
approached
.42 .34 .43
25. Cuts
himself/herself
off from
environment
.32 .30 .21
G Social Isolation .45 .65 .66 .20 .42 .41 .41 .66
16. Is rejected by
other patients .39 .25 .46
20. Openly rejects
contact with
others
.56 .21 .39
32. Calls out .42 .13 .37
Internal consistency
From the nine subscales of the QUALIDEM for people with mild to severe dementia, only ve showed
acceptable to excellent internal consistencies varying from ρ = 0.69 to 0.95 (“care relationship”, “positive
affect”, “restless tense behaviour”, “social relations” and “having something to do”, see Table 4). Five out
of six subscales from the QUALIDEM for people with very severe dementia showed at least acceptable
internal consistencies (ρ = 0.65 to 0.91, Table 5). Only “social relations” had an insucient reliability (ρ =
0.55).
Discussion
The aim of the current study was to investigate whether the item distribution, scalability and internal
consistency of the dementia-specic QUALIDEM instrument can be replicated in a hospital context. As a
reference for comparison, we chose two studies from Dichter et al. [36] and Arons et al. [37], which
represent recent works on analysing the item distribution and testing the scalability and internal
consistency of the QUALIDEM in nursing home settings.
Page 21/28
Item distribution
The investigation of the item distribution of the QUALIDEM demonstrated a moderately balanced
distribution of the four response options. Twenty-six out of 37 items for people with mild to severe
dementia showed an acceptable item diculty, and only two out of 18 items for people with very severe
dementia showed a ceiling effect. The proportion of missing values varies from 0.6 to 36.0% and is not
always in an acceptable range (< 10%); particularly for the items in the “social relations” dimension; this
proportion was high due to the frequent use of the failure rating category “not applicable”. One reason for
these results might be a missing cross-cultural adaption of the QUALIDEM measurement for the German
context and in particular for the German hospital settings.
These descriptive ndings are widely in line with previous results. Yet, Arons et al. [37], for example,
reported that with one exeption (item “feels at home on the ward”) all other items had less than 1%
missing values. A recent study by Dichter et al. [38] showed fewer ceiling effects, but the German-
language QUALIDEM version 2.0 was used here, which offers a total of seven assessment options
(“never”, “very rarely”, “rarely”, “sometimes”, “often”, “frequently” and “very frequently”) to choose from. In
the present study, the original German version 1.0 of the QUALIDEM was used with only four assessment
options. Hence, the small number of rating options could be the reason for the high number of ceiling
effects (and lower internal consistency).
It is also noticeable that almost all item raw scores in seven subscales for people with mild to severe
dementia, but no items in two subscales (”positive affect”, “having something to do”) are left-skewed in
distribution. The most obvious right-skewness in one dimension appears in item 18 (“takes care of other
patients”). Unlike the other items, here negative assessments prevail from the proxy perspective of the
study nurses. Researchers must consider the challenges inherent in rating before determining the QoL
outcome and adapt their methodological approaches accordingly.
Scalability
The subscales “care relationship” and “social relations” have moderate scalability, but still scoring good
or slightly better than the same subscales in the previous studies [36, 37]. The subscale “care
relationship” might be improved by omitting the items “rejects help from nursing assistants” (item 4) and
“accuses others” (item 17). Regarding the subscale “social relations”, the same holds true for the item
“feels at ease in the company of others” (item 34). Especially the item “rejects help from nursing
assistants” had a higher scalability in both studies from Dichter et al. [36] and Arons et al. [37]. This
indicates that a specic adaptation of the QUALIDEM for hospital settings seems reasonable.
“Negative affect” and “social isolation” show weak scalability. While the result for “social isolation” is at
least comparable to Dichter et al. [36], “negative affect” has a remarkably lower scalability compared to
the other study. These results are less surprising, given that limitations according to either weak or
inconsistent scalability of these two subscales have also been recognized by the authors of the
QUALIDEM instrument [11]. One explanation might be diculties according to the interrater reliability.
Page 22/28
Personal interviews with people using the QUALIDEM revealed that items like “cries” or “is sad” are
interpreted in very different ways, which seems to make those items prone to subjectively biased
perceptions of patients’ moods.
The subscales “positive self-image” and “feeling at home” were not scalable. For the items of the two
subscales, we assume that both the hospital setting as well as the shorter observation period – as
compared to nursing homes – might explain these results. Looking at single items, the item “wants to get
off the ward” (item 39) has a comparably higher scalability than the remaining items of the subscale
“feeling at home”, which is reasonable in a hospital context. The distributions of responses to this item
has a rather uniform shape. This implies that there is a notable amount of PwD, who want to get off the
ward. When it comes to revising the QUALIDEM for a hospital context, this item should still be considered
in order to adequately measure QoL.
Within the group of patients with very severe dementia, we found strong scalability for “care relationship”,
“positive aspect”, “negative affect” and “restless tense behaviour”. The differences in scalability between
the group of mild to severe dementia and very severe dementia can partly be explained due to the reduced
amount of items for some subscales in the latter group. Low scalable items like “rejects help from
nursing assistants” (item 4) or “accuses others” (item 17) were omitted for the subscale “care
relationship” in the reduced QUALIDEM version for patients with very severe dementia. However, the items
of “negative affect” have a much higher scalability for patient with very severe dementia as compared to
the group with mild to severe dementia.
Internal consistency
The internal consistency results only partially correspond to the results of the reference studies from
Dichter et al. [36] and Arons et al. [37]. For patients with mild to severe dementia, the subscales "care
relationship", "positive affect", “restless, tense behaviour“, “social relations” and “having something to do”
showed a similarly acceptable to excellent internal consistencies. Comparatively, there was signicantly
less homogeneity for the subscale “negative affect”, "positive self-image" and "feeling at home". In
accordance with both studies, an insucient level of internal consistency was determined for the
subscale “social isolation”, while better characteristics (rho, alpha) were only found for “having something
to do”.
The QUALIDEM subscales for people with a very severe dementia showed similar results as in the
previous studies [36, 37]. For the subscales “care relationship”, “positive affect”, “negative affect”,
“restless, tense behaviour“ and “social isolation” a good homogeneity could be determined – even better
values in three subscales. Comparably, the subscale “social relations” showed a similarly poor internal
consistency. One reason for lower Cronbach's alpha values can be affected in the rather small number of
items of subscales. This is typical of Cronbach's alpha values that increase as the number of items
increases [39].
Page 23/28
Our main nding suggests that for most of the subscales, especially for the group of people with very
severe dementia, the results from the internal consistency analysis as well as the MSA were at least as
good as in the two reference studies, and sometimes even better. Nevertheless, for all subscales, 50% of
the proxy participants reached a score of 50 or higher, regardless of dementia severity. This result raises
the question of the QUALIDEM’s sensitivity for change, which has not been assessed. Information on
responsiveness is scarce in general, which highlights the need for research on this topic. To use QoL as
an outcome in intervention studies, evidence of the QUALIDEM’s sensitivity for change is required.
Strength and limitations
The article is based on the rst study using data from inpatient care to analyse psychometrics of the
dementia-specic QUALIDEM instrument in Germany. There are, however, a number of limitations. There
was a high proportion of missing values in some items, but tackling this issue with imputation
techniques is feasible. Individual results relating item diculty may be enhanced by using German-
language QUALIDEM version 2.0, which did not yet exist at the time the data was collected in the DAVID
project. Furthermore, reliability scores (ρ, Cronbach’s α) were problematic for scales with less than 10
items. This problem was already identied by the authors of the QUALIDEM [11], which led to the
development of the revised second version of that assessment instrument. Unfortunately, it was not
possible to measure the interrater reliability in the DAVID project. Thus, we could not clearly identify the
causes for the low scalability scores of some subscales. Another limitation of the study relates to the
hypothesising. In the run-up to the study, it was only possible to fall back on preliminary empirical
ndings in the context of the formation of hypotheses, which were dicult to interpret due to the use of
different assessment instruments. Despite these limitations, one of the rst applications in hospital
context is arguably a strength of this study, providing evidence that the QUALIDEM is a useful tool to
measure QoL of PwD in hospitals.
Conclusions
Despite the limitations mentioned above (most are general diculties in measuring QoL) the instrument’s
psychometric properties justify its use in the context of hospital research. In comparison with a previous
evaluation of the scalability and reliability of the QUALIDEM in a long-term care setting, the application in
a hospital setting leads to very similar, acceptable results for people with mild to severe dementia. For
people with very severe dementia, the QUALIDEM instrument seems to t even better in a hospital context.
Results suggest either a revision of unsatisfactory items or a general reduction to six to seven subscales
for all PwD. In addition, an investigation of the inter-rater reliability of the QUALIDEM is recommended.
Declarations
Ethics approval and consent to participate
Not applicable.
Page 24/28
Consent for publication
Not applicable.
Availability of data and materials
The dataset supporting the conclusions of this article as well as the R source code to reproduce the
results are available in the OSF repository [40] at https://osf.io/vunmf/.
Competing interests
The authors declare that the research was conducted in the absence of any commercial or nancial
relationships that could be construed as a potential conict of interest.
Funding
This study received no external funding.
Authors' contributions
DL, MND, SN and CK OK developed the research question. DL prepared, analyzed and interpreted the data,
and drafted and nalized the manuscript. MND, SN and CK substantially contributed to interpreting the
data, drafting the manuscript, and critically revised and approved the nal manuscript. All authors
contributed to the article and approved the submitted version.
Acknowledgements
Not applicable.
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Figures
Figure 1
Distribution of QUALIDEM Scores from each subscale for patients with mild to severe dementia (n=344)
