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Lüdeckeetal.
Health and Quality of Life Outcomes (2023) 21:12
https://doi.org/10.1186/s12955-023-02094-1
RESEARCH
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Open Access
Health and Quality
of Life Outcomes
Item distribution, scalability andinternal
consistency oftheQUALIDEM quality oflife
assessment forpatients withdementia inacute
hospital settings
Daniel Lüdecke1*, Martin Nikolaus Dichter2, Stefan Nickel1 and Christopher Kofahl1
Abstract
Background Quality of life (QoL) of people with dementia (PwD) is an important indicator of quality of care. Study-
ing the impact of acute hospital settings on PwD’s QoL requires assessment instruments that consider environmental
factors. Until now, dementia-specific QoL instruments have not yet demonstrated their feasibility in acute hospitals
because their use takes up too much time or their validity depends on observation periods that usually exceed the
average length of hospital stays. Therefore, validated instruments to study QoL-outcomes of patients with dementia in
hospitals are needed.
Methods Data stem from a study that analyzed the impact of a special care concept on the QoL of patients with
dementia in acute hospitals. Total sample size consisted of N = 526 patients. Study nurses were trained in using an
assessment questionnaire and conducted the data collection from June 2016 to July 2017. 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 insufficient 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 = 0.65–0.91). Only the item social relations
had insufficient 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 fit 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 necessary because the qualification of the nurses and the length of stay
*Correspondence:
Daniel Lüdecke
d.luedecke@uke.de
Full list of author information is available at the end of the article
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
of the patients in the hospital differ from the previous investigations of the inter-rater reliability of QUALIDEM in the
nursing home.
Keywords QUALIDEM, Quality of life, Patients with dementia, Hospitals, Validation
Background
Acute hospitals face the challenge of changes in demo-
graphic and clinical characteristics of people who need
acute health care, which leads to an increased prevalence
of people with dementia (PwD) [1, 2]. According to cur-
rent studies and systematic reviews, there are no precise
numbers on the prevalence of cognitive impairment in
patients in hospitals. Most studies, however, indicate that
approximately 40% of inpatients have at least mild cogni-
tive impairments or are diagnosed with dementia [3].
Many hospitals and their personnel are insufficiently
prepared for those people with cognitive impairments,
especially in acute care units predominantly focusing on
somatic diseases [4]. is results in an increased likeli-
hood of complications during the hospital stay and post-
operative complications, which in turn affect the quality
of life (QoL) of PwD [5–7]. However, QoL is an impor-
tant indicator of quality of care and a major dimension
when assessing patient reported outcomes. is particu-
larly holds true for older people, regarding global out-
come measures for interventions [8, 9].
erefore, psychometrically validated instruments to
measure QoL of PwD in hospital contexts are strongly
needed. A recent systematic review and meta-regression
analysis by Li etal. reveals a number of generic instru-
ments such as the EuroQol five-dimension questionnaire
(EQ-5D) and dementia-specific instruments such as the
DEMQOL-U [10]. Most instruments, however, are not
feasible to assess QoL in acute hospitals. Usually, QoL
instruments for PwD are only validated in nursing home
care settings. e use of instruments developed for a
nursing home care settings take too long when used in
hospitals. eir validity depends on observation periods
that usually exceed the average length of a hospital stay.
Additionally, the critical life-event of hospitalization has
a direct impact on QoL. Another issue is the qualifica-
tions and experience of nurses in caring for people with
dementia, which differs between hospitals and nursing
homes. is might be relevant for a proxy instrument.
erefore, previous studies on psychometric properties
of QoL instruments are not directly transferable to a hos-
pital setting.
is also applies to the recently developed QUALIDEM
instrument, too [11, 12]. QUALIDEM is based on the
adaptation-coping model [13] and defines dementia-spe-
cific QoL as a multidimensional assessment of the indi-
vidual person-environment system in terms of adaptation
to the perceived consequences of dementia [11]. is
means that the dementia-specific QoL is the result of a
successful or unsuccessful adaptation of the PwD 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 ver-
sion of the QUALIDEM instrument can be replicated in
a hospital context, to draw conclusions about the appli-
cability of the QUALIDEM in hospital research regard-
ing PwD. However, proxy ratings with an instrument as
QUALIDEM are accompanied by methodological chal-
lenges, 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, Vali-
dation at an Internal medicine ward for patients with
Dementia) that compared the quality of care for patients
with dementia within an internal medicine unit using a
specialized dementia care concept as opposed to regular
care in acute hospitals. e study was designed as a cross-
sectional 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 asso-
ciation of Hamburg. e ethical committee approved
the proposal and confirmed that the study conforms to
ethical and legal requirements (approval code PV5102).
Study participants were not able to give their informed
consent due to their cognitive impairments. However, as
data mostly derived from the hospitals’ regular documen-
tation, and as data was completely anonymous, the ethics
committee waived the need of an informed consent.
First sample site
e special care ward “DAVID” was an internal medi-
cine ward in the Protestant Hospital Alsterdorf, a not-
for-profit organization, and had 14 beds. During the
12months of data collection, 349 patients were treated.
e ward employed nine care workers as nursing staff.
Key components of the special care concept were a spe-
cific architectonical design, including a homelike lounge
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
or a specific coloring of doors and walls; doctors, nurses
and service staff were trained in coping with challenging
behavior and other dementia related issues, e.g. using
basal stimulation or validation therapy; mobile devices
for diagnostics, to perform as many treatments as pos-
sible in the different rooms of the special care ward;
involvement of relatives regarding assessment, care and
discharge planning; and regular therapeutic offers like
occupational or speech therapy, plus social offers like
music, playing games or nurses spending more time than
usual to care for the patients.
Second sample site
e regular care ward was part of a larger private-com-
pany hospital with emergency hospitalization. It had 80
beds and during the 12months of data collection, about
3500 patients were treated in this internal medicine ward.
Twenty-six employees worked as care staff in this ward.
Trainees supported the care team. e regular care ward
had no specific care concept for dementia patients. e
care staff was not particularly trained in dementia topics.
Data collection andparticipants
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. e assessment question-
naire comprised items on different domains like QoL,
functional limitations, cognitive status, comorbidities,
agitation or challenging behavior. Participants were
observed for about 1 week (depending on the length of
stay). e study nurses then rated the participants’ out-
comes for these domains. Two study nurses were respon-
sible 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 prob-
lems. 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 clarified dementia diagnosis, and to
identify further patients who would qualify for the study.
Patients were excluded when they were not responsive or
completely confined to bed due to severe health-related
dependency. As both care wards had no particular selec-
tion criteria for patients such as age, mobility, or the
main diagnosis that lead to hospital admission, no further
exclusion criteria for the study were defined. e total
sample size for the present analysis consists of N = 526
people with dementia (special care ward: n = 333; reg ular
care ward: n = 193).
Measurements
For the description of the sample, information on age,
gender, length of stay, functional limitations, challeng-
ing behavior, comorbidities and quality of life were used.
Functional limitations in daily living were assessed with
the Barthel-Index [17]. is score ranged from 0 (com-
pletely dependent) to 100 points (no basic functional lim-
itations). Agitation and challenging behavior of patients
was assessed using the Pittsburgh Agitation Scale (PAS)
[18] ranging from 0 to 16 points (higher scores indicate
stronger agitation). A modified version of the Charlson’s
Comorbidity Index (CCI) was built to represent comor-
bidities and chronical diseases [19].
e QUALIDEM (Version 1) [11, 12] was used to
assess the QoL of PwD. QUALIDEM for people with
mild to severe dementia comprises 37 items reflecting
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 behavior” (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 some-
thing 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), hence 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. e rea-
son is that for some items higher values mean a better
QoL, while other items were coded so that lower values
indicate better QoL. us, 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 hos-
pital setting.
e Mini Mental Status Examination test [20] was used
to assess the severity of dementia. e score ranges from
zero (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
Sample description
e descriptions of the participants, the missing data,
and the item distributions were based on descriptive
statistics. Statistically significant differences of p < 0.05
between the two groups of “mild to severe” and “very
severe” dementia were tested using t-tests, χ2-tests or
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
Mann–Whitney-U-tests, depending on the level of
measurement and distribution of variables. Since the
QUALIDEM subscales differed in the number of items
contributing to each subscale, we normalized the sub-
scale scores (for the figures only), so each subscale in the
figures ranged from 0 to 1. is allowed a more intuitive
comparison of QUALIDEM subscales because they no
longer had different ranges.
Item distribution andoor/ceiling eects
e item distribution for all QUALIDEM items was
reported and the difficulty for each item was calculated
to indicate floor (item difficulty < 0.2) or ceiling (item
difficulty > 0.8) effects per item, which means items had
poor discrimination if these thresholds were exceeded
[21]. Furthermore, floor and ceiling effects for subscale
scores and the QUALIDEM total score were determined
by calculating the proportions of PwD appearing in the
lower or upper 10% of each score [22]. Floor or ceiling
effects larger than 15% were considered as statistically
significant and indicated poor discrimination of a scale
[23].
Known‑group validity
To assess how well the QUALIDEM distinguishes among
distinct groups, we calculated the known-group validity
[24]. Distinct groups were build based on five different
characteristics: age, sex, functional limitations (Barthel-
Index), agitation and challenging behavior (PAS-score)
and morbidity (CCI). erefore, all continuous char-
acteristics were dichotomized at the median. For each
characteristic, hypotheses were defined a priori. Prior
assumptions were based on research on this topic [25,
26]:
1. QoL is not significantly associated with age, hence
we expect no significant differences in QoL by age,
because our selection of the sample only contains
older aged patients.
2. QoL is not significantly associated with gender. We
expect no significant differences between male and
female patients.
3. QoL is negatively associated with functional limita-
tions. We expect lower QoL scores for higher func-
tional limitations.
4. We expect significantly lower QoL when PwD show
higher agitation and challenging behavior.
5. QoL is negatively associated with morbidity. e
higher the number of comorbidities, the lower the
QoL scores.
Differences among groups were tested for statistical
significance using one-sided or two-sided t-tests. Cohen’s
d was used to indicate the effect size. A coefficient < 0.2
was considered as very small, 0.2 to < 0.5 as small, 0.5 to
< 0.8 as medium and 0.8 and higher as large effect [27].
Scalability andinternal consistency
Scalability and internal consistency of the QUALIDEM
subscales were analyzed with the confirmatory Mokken
scale analysis (MSA) [28–30], which is a scaling pro-
cedure for both dichotomous and ordinal polytomous
items. It assesses 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 ordi-
nal data [12, 31, 32]. e scalability of scales was meas-
ured by Loevinger’s coefficient H, in short just “H”. It
indicates the internal correlation of each subscale. Mok-
ken [28] proposed the following rules of thumb for this
coefficient: A scale was considered weak if 0.3 ≤ H < 0.4,
moderate if 0.4 ≤ H < 0.5, and strong if H ≥ 0.5. If H was
lower than 0.3, an item or scale was considered “not
scalable”, which means items were unrelated, thus not
reflecting the underlying concept of a scale. e corre-
lation between a single item and the remaining items of
a scale was expressed by the value “Hi”, which should be
non-negative to fulfil the assumptions of the MSA, and
should be higher than 0.3 to show at least moderate dis-
crimination power, thereby being useful for the scale [24].
e criterion of the MSA (“crit”, [33]) was used to check
monotonicity assumptions. is 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 [34].
Finally, the Molenaar Sijtsma statistic (“rho”, ρ) as well
as Cronbach’s α were calculated as reliability measures
for the internal consistency of scales [35, 36], the latter
mainly for comparison to other study results. For both
ρ and α, a value smaller than 0.6 indicated insufficient
internal consistency of a scale, while values above 0.7
were acceptable or satisfying. Scales with ρ or α between
0.6 and 0.7 were sufficient, but questionable.
For the present MSA, missing values were imputed
using the suggested two-way imputation [37, 38]. In a
second step, missing data were imputed using the mul-
tivariate imputation by chained equations method [39],
in order to compare how different imputation methods
affect the results of the MSA (these results are shown in
the Additional file1: TableA1).
All analyzes were performed using the R statistical
package [40] with the R packages mokken [41], mice [39],
effectsize [42] and sjPlot [43]. Figures were created using
ggplot2 [44]. Analyzes were carried out for the two sub-
groups “mild to severe dementia” (MMSE ≥ 10) and “very
severe dementia” (MMSE < 10) separately.
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
Results
Characteristics ofthesample
Table 1 shows the sample characteristics. e sam-
ple consisted of 526 patients—344 people with mild to
severe dementia, and 182 with very severe dementia.
60.6% of the participants were female. e mean age
was 80.5 years and the average length of hospital stay
was about 9.4 days. ese characteristics were simi-
lar for both sub-groups (mild to severe and very severe
dementia).
e average Barthel-Index in the sample was 36.7, but
comparably higher for people with mild to severe demen-
tia (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. To complete the sample descrip-
tion, we provided the mean values and their SD for each
QUALIDEM subscale in Table2. However, these are not
directly comparable due to different numbers of items
between the two groups and thereby different ranges for
the subscales. Looking at the normalized scores of the
QUALIDEM subscales for people with mild to severe
dementia in Fig.1, we found higher QoL for “care rela-
tionship”, “restless behavior”, “positive self-image” and
“social isolation”, while especially the domain of “hav-
ing something to do” is associated with the lowest QoL
score. People with very severe dementia showed higher
QoL scores for “negative affect” and “restless behavior”,
while “positive affect” and “social relations” were those
domains with the lowest QoL scores (Fig.2).
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 3276 responses of the 18 QUALI-
DEM items (10.7%) were missing.
Item distribution
Table3 shows the distribution of items of the QUALI-
DEM for people with mild to severe dementia. e dis-
tribution of items varies between the different subscales
of the QUALIDEM. Eleven items out of six subscales
(“care relationship”, “negative affect”, “restless tense
behavior”, “positive self-image”, “social isolation” or “feel-
ing at home”) showed a ceiling effect with a left-skewed
distribution from “often” to “never”. In most cases, the
response category for these items was “never” (from
about 45% to 75%, except for the two items “cries” and
“is rejected by other patients”, which have a proportion
of 35.8% and 37.8%, respectively). 11 items show ceil-
ing effects, while two items show floor effects. ose
subscales where at least half of the items have ceiling or
Table 1 Characteristics of the sample, shown are proportions of sample (%), or mean and standard deviation (in parenthesis)
Barthel-Index: 0–100 (higher = better functioning); QUALIDEM: 0–100 (higher = better QoL)
a χ2-test
b t-test
c Mann–Whitney-U test
Characteristic Mild to severe dementia
(n = 344) Very severe dementia
(n = 182) Total (n = 526) p value of
dierence
Proportion female, % 59.3 63.2 60.6 0.439a
Mean age (SD) 81.5 (9.5) 78.7 (12.1) 80.5 (10.6) 0.007b
Mean barthel-index (SD) 45.9 (28.5) 19.4 (24.4) 36.7 (29.9) < 0.001c
Mean PAS-score (SD) 2.9 (3.1) 4.1 (3.3) 3.3 (3.2) < 0.001c
Mean CCI (SD) 2.8 (1.6) 2.7 (1.6) 2.8 (1.6) 0.292c
Mean length of stay, in days (SD) 9.2 (5.4) 9.7 (7.8) 9.4 (6.3) 0.732c
Mean QUALIDEM total score (SD) 51.2 (16.0) 40.1 (16.5) 47.3 (17.0) < 0.001b
Table 2 Sample characteristics of the QUALIDEM subscales,
mean and standard deviation (in parenthesis)
* Mean values are not directly comparable because number of items per
subscale dier between patients with mild to severe and patients with very
severe dementia
Mean QUALIDEM subscale
scores* (SD) Mild to severe
dementia (n = 344) Very severe
dementia
(n = 182)
(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 behavior 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
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
floor effects are “negative affect”, “positive self-image”
and “feeling at home”. e 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. e other scales showed no consistent pattern
across items.
e distributions of the QUALIDEM items for people
with very severe dementia (Table 4) show comparable
patterns as in Table3, however, with a less pronounced
proportion of the response category “never”. Only two
items show ceiling effects (“makes an anxious impres-
sion” and “openly rejects contact with others”). We found
no floor effects in the six subscales of the QUALIDEM
items for people with very severe dementia.
Floor andceiling eects forQUALIDEM subscales
Six out of nine subscales ("care relationship”, “positive
affect”, “negative affect”, “restless tense behavior”, “positive
self-image” and “social isolation”) showed significant ceil-
ing effects for the group of patients with mild to severe
dementia. Significant floor effects for this group were
found in one subscale (“having something to do”). e
total score of the QUALIDEM showed no floor nor ceil-
ing effects. For patients with very severe dementia, three
out of six subscales showed significant ceiling effects
(“negative affect” and “social isolation”), while “positive
affect” was the only subscale with a significant floor effect
(see Table5).
Known‑group validity
Table 6 shows the results for the known-group valid-
ity. For patients with mild to severe dementia, all a pri-
ori defined hypotheses were accepted, indicating a high
validity of the QUALIDEM score for the five defined
groups. Medium to large effects were found for differ-
ences between the distinct groups “lower/higher agi-
tation and challenging behavior” and “lower/higher
comorbidities”. For people with very sever dementia, only
the hypothesis that patients with higher comorbidities
had a lower QoL was rejected. Differences between the
distinct groups “lower/higher agitation and challenging
behavior” and “lower/higher comorbidities” were consid-
ered as large effects.
Scalability
Table7 shows the results of the MSA from the QUALI-
DEM for patients with mild to severe dementia. ree
of the nine subscales show strong scalability (“posi-
tive affect”, H = 0.77; “restless tense behavior”, H = 0.55;
“having something to do”, H = 0.56). e subscales “care
relationship” and “social relations” have moderate scal-
ability (H = 0.43 and H = 0.47 respectively). Most of their
Fig. 1 Distribution of QUALIDEM Scores from each subscale for patients with mild to severe dementia (n = 344)
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
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. e items “is sad” (H = 0.26) and “is rejected
by other patients” (H = 0.28) are not scalable. e sub-
scales “positive self-image” (H = 0.17) and “feeling at
home” (H = 0.16) were not scalable.
e MSA for the group of people with very severe
dementia is shown in Table8. All six subscales were scal-
able (0.34 ≤ H ≤ 0.71). e scalability could be considered
as weak for “social relations”, moderate for “social isola-
tion” and strong for the other remaining four subscales.
Internal consistency
From the nine subscales of the QUALIDEM for people
with mild to severe dementia, only five showed accept-
able to excellent internal consistencies varying from
ρ = 0.69 to 0.95 (“care relationship”, “positive affect”,
“restless tense behavior”, “social relations” and “hav-
ing something to do”, see Table7). Five out of six sub-
scales from the QUALIDEM for people with very severe
dementia showed at least acceptable internal consisten-
cies (ρ = 0.65–0.91, Table 8). Only “social relations” had
an insufficient reliability (ρ = 0.55).
Discussion
e aim of the current study was to investigate whether
the item distribution, scalability and internal consistency
of the dementia-specific QUALIDEM instrument can be
replicated in a hospital context. As a reference for com-
parison, we chose one study from Dichter etal. [45] and
one from Arons etal. [46], which represent recent works
on analyzing the item distribution and testing the scal-
ability and internal consistency of the QUALIDEM in
nursing home settings.
Item distribution
e investigation of the item distribution of the QUAL-
IDEM demonstrated a moderately balanced distribu-
tion of the four response options. Twenty-six out of 37
items for people with mild to severe dementia showed
an acceptable item difficulty, and only two out of 18
items for people with very severe dementia showed
Fig. 2 Distribution of QUALIDEM Scores from each subscale for patients with very severe dementia (n = 182)
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
Table 3 Item distribution (range 0–3) of nine QUALIDEM subscales for people with mild to severe dementia, including missing values
and mean/SD (n = 344)
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
Item Nr Subscale (Item) 0 1 2 3 Missing values Item diculty
A Care relationship
4 Rejects help from nursing assistantsa20 (5.8%) 40 (11.6%) 48 (14.0%) 217 (63.1%) 19 (5.5%) 0.81
7Is angrya33 (9.6%) 70 (20.3%) 82 (23.8%) 157 (45.6%) 2 (0.6%) 0.69
14 Has conflicts with nursing assistantsa29 (8.4%) 66 (19.2%) 76 (22.1%) 170 (49.4%) 3 (0.9%) 0.71
17 Accuses othersa26 (7.6%) 55 (16.0%) 61 (17.7%) 183 (53.2%) 19 (5.5%) 0.74
24 Appreciates help he or she receivesb29 (8.4%) 57 (16.6%) 90 (26.2%) 162 (47.1%) 6 (1.7%) 0.71
31 Accepts helpb11 (3.2%) 33 (9.6%) 90 (26.2%) 194 (56.4%) 16 (4.7%) 0.81
33 Criticizes the daily routinea16 (4.7%) 38 (11.0%) 60 (17.4%) 225 (65.4%) 5 (1.5%) 0.82
B Positive aect
1Is cheerfulb52 (15.1%) 78 (22.7%) 102 (29.7%) 98 (28.5%) 14 (4.1%) 0.58
5Radiates satisfactionb37 (10.8%) 72 (20.9%) 124 (36.0%) 105 (30.5%) 6 (1.7%) 0.63
8 Is capable of enjoying things in daily lifeb25 (7.3%) 81 (23.5%) 134 (39.0%) 100 (29.1%) 4 (1.2%) 0.64
10 Is in a good moodb39 (11.3%) 84 (24.4%) 124 (36.0%) 94 (27.3%) 3 (0.9%) 0.60
21 Has a smile around the mouthb38 (11.0%) 85 (24.7%) 109 (31.7%) 98 (28.5%) 14 (4.1%) 0.60
40 Mood can be influenced in positive senseb30 (8.7%) 97 (28.2%) 105 (30.5%) 109 (31.7%) 3 (0.9%) 0.62
C Negative aect
6 Makes an anxious impressiona16 (4.7%) 16 (4.7%) 40 (11.6%) 255 (74.1%) 17 (4.9%) 0.88
11 Is sada8 (2.3%) 18 (5.2%) 50 (14.5%) 248 (72.1%) 20 (5.8%) 0.89
23 Criesa82 (23.8%) 69 (20.1%) 67 (19.5%) 123 (35.8%) 3 (0.9%) 0.56
D Restless tense behavior
2 Makes restless movementsa23 (6.7%) 50 (14.5%) 69 (20.1%) 196 (57.0%) 6 (1.7%) 0.77
19 Is restlessa13 (3.8%) 20 (5.8%) 51 (14.8%) 258 (75.0%) 2 (0.6%) 0.87
22 Has tense body languagea27 (7.8%) 44 (12.8%) 76 (22.1%) 182 (52.9%) 15 (4.4%) 0.75
E Positive self‑image
27 Indicates he or she would like more helpa7 (2.0%) 21 (6.1%) 55 (16.0%) 243 (70.6%) 18 (5.2%) 0.88
35 Indicates not being able to do anythinga13 (3.8%) 50 (14.5%) 90 (26.2%) 173 (50.3%) 18 (5.2%) 0.77
37 Indicates feeling worthlessa19 (5.5%) 23 (6.7%) 27 (7.8%) 251 (73.0%) 24 (7.0%) 0.86
F Social relations
3 Has contact with other patientsb68 (19.8%) 95 (27.6%) 91 (26.5%) 68 (19.8%) 22 (6.4%) 0.50
12 Responds positively when approachedb6 (1.7%) 39 (11.3%) 110 (32.0%) 185 (53.8%) 4 (1.2%) 0.80
18 Takes care of other patientsb233 (67.7%) 34 (9.9%) 13 (3.8%) 16 (4.7%) 48 (14.0%) 0.12
25 Cuts himself/herself off from environmenta30 (8.7%) 59 (17.2%) 60 (17.4%) 179 (52.0%) 16 (4.7%) 0.73
29 Is on friendly terms with one or more patientsb135 (39.2%) 60 (17.4%) 65 (18.9%) 56 (16.3%) 28 (8.1%) 0.38
34 Feels at ease in the company of othersa37 (10.8%) 45 (13.1%) 32 (9.3%) 228 (66.3%) 2 (0.6%) 0.77
G Social Isolation
16 Is rejected by other patientsa81 (23.5%) 53 (15.4%) 76 (22.1%) 130 (37.8%) 4 (1.2%) 0.58
20 Openly rejects contact with othersa17 (4.9%) 23 (6.7%) 48 (14.0%) 241 (70.1%) 15 (4.4%) 0.85
32 Calls outa39 (11.3%) 66 (19.2%) 64 (18.6%) 173 (50.3%) 2 (0.6%) 0.69
H Feeling at home
13 Indicates that he or she is boreda19 (5.5%) 26 (7.6%) 45 (13.1%) 235 (68.3%) 19 (5.5%) 0.84
28 Indicates feeling locked upa2 (0.6%) 20 (5.8%) 55 (16.0%) 237 (68.9%) 30 (8.7%) 0.89
36 Feels at home on the wardb222 (64.5%) 36 (10.5%) 41 (11.9%) 20 (5.8%) 25 (7.3%) 0.19
39 Wants to get off the warda75 (21.8%) 78 (22.7%) 51 (14.8%) 120 (34.9%) 20 (5.8%) 0.59
I Having something to do
26 Finds things to do without help from othersb87 (25.3%) 83 (24.1%) 93 (27.0%) 65 (18.9%) 16 (4.7%) 0.47
38 Enjoys helping with chores on the wardb145 (42.2%) 31 (9.0%) 28 (8.1%) 16 (4.7%) 124 (36.0%) 0.20
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
a ceiling effect. e proportion of missing values var-
ies from 0.6 to 36.0% and is not always in an accept-
able range (< 10%); this particularly holds true for the
items in the “social relations” dimension. Here the pro-
portion of missing values was high due to the frequent
use of the failure rating category “not applicable”. One
reason for these results might be a missing cross-cul-
tural adaption of the QUALIDEM measurement for the
German context and in particular for German hospital
settings.
Table 4 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 Item diculty
A Care relationship
7Is angrya26 (14.3%) 29 (15.9%) 41 (22.5%) 80 (44.0%) 6 (3.3%) 0.66
14 Has conflicts with nursing assistantsa30 (16.5%) 42 (23.1%) 33 (18.1%) 71 (39.0%) 6 (3.3%) 0.61
31 Accepts helpb63 (34.6%) 43 (23.6%) 37 (20.3%) 32 (17.6%) 7 (3.8%) 0.41
B Positive aect
5Radiates satisfactionb39 (21.4%) 57 (31.3%) 50 (27.5%) 30 (16.5%) 6 (3.3%) 0.47
8 Is capable of enjoying things in daily lifeb48 (26.4%) 49 (26.9%) 61 (33.5%) 18 (9.9%) 6 (3.3%) 0.43
21 Has a smile around the mouthb53 (29.1%) 46 (25.3%) 48 (26.4%) 29 (15.9%) 6 (3.3%) 0.43
40 Mood can be influenced in positive senseb50 (27.5%) 49 (26.9%) 51 (28.0%) 25 (13.7%) 7 (3.8%) 0.43
C Negative aect
6 Makes an anxious impressiona4 (2.2%) 4 (2.2%) 10 (5.5%) 101 (55.5%) 63 (34.6%) 0.92
23 Criesa55 (30.2%) 30 (16.5%) 17 (9.3%) 72 (39.6%) 8 (4.4%) 0.54
D Restless tense behavior
2 Makes restless movementsa26 (14.3%) 38 (20.9%) 33 (18.1%) 79 (43.4%) 6 (3.3%) 0.65
19 Is restlessa18 (9.9%) 16 (8.8%) 21 (11.5%) 123 (67.6%) 4 (2.2%) 0.80
22 Has tense body languagea11 (6.0%) 26 (14.3%) 21 (11.5%) 62 (34.1%) 62 (34.1%) 0.71
F Social relations
3 Has contact with other patientsb98 (53.8%) 36 (19.8%) 22 (12.1%) 6 (3.3%) 20 (11.0%) 0.20
12 Responds positively when approachedb23 (12.6%) 38 (20.9%) 67 (36.8%) 50 (27.5%) 4 (2.2%) 0.60
25 Cuts himself/herself off from environmenta22 (12.1%) 29 (15.9%) 15 (8.2%) 55 (30.2%) 61 (33.5%) 0.62
G Social Isolation
16 Is rejected by other patientsa57 (31.3%) 22 (12.1%) 23 (12.6%) 73 (40.1%) 7 (3.8%) 0.55
20 Openly rejects contact with othersa9 (4.9%) 7 (3.8%) 13 (7.1%) 90 (49.5%) 63 (34.6%) 0.85
32 Calls outa49 (26.9%) 36 (19.8%) 17 (9.3%) 72 (39.6%) 8 (4.4%) 0.55
Table 5 Floor and ceiling effects for QUALIDEM subscales and total score, for patients with mild to severe dementia (n = 344) and
patients with very severe dementia (n = 182)
* Eects were considered signicant if the proportion of oor or ceiling eects exceeded 15%
Item Nr Subscale (Item) Mild to severe dementia Very severe dementia
Flooring (%) Ceiling (%) Flooring (%) Ceiling (%)
A Care relationship 0.6 34.9* 6.6 9.9
B Positive affect 4.4 20.9* 19.8* 8.2
C Negative affect 0.0 27.0* 1.1 26.9*
D Restless tense behavior 0.9 39.8* 2.7 24.2*
E Positive self-image 0.0 36.3* – –
F Social relations 0.6 3.8 2.7 1.1
G Social isolation 0.9 21.8* 0.5 17.0*
H Feeling at home 0.3 5.8 – –
I Having something to do 20.9* 2.9 – –
Total QUALIDEM-score 0.0 5.5 0.0 4.4
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
ese descriptive findings are widely in line with previ-
ous results. Yet, Arons etal. [46], for example, reported
that with one exception (item “feels at home on the
ward”) all other items had less than 1% missing values.
A recent study by Dichter etal. [47] showed fewer ceil-
ing effects, however, the German-language QUALIDEM
version 2.0 was used here, which offers a total of seven
assessment options to choose from (“never”, “very rarely”,
“rarely”, “sometimes”, “often”, “frequently” and “very fre-
quently”). 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 ceil-
ing 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. e
most obvious right-skewness in one dimension appears
in item 18 (“takes care of other patients”). Here, unlike
in other items, negative assessments by study nurses are
dominant. Researchers must consider the challenges
inherent in rating before determining the QoL outcome
and adapt their methodological approaches accordingly.
Floor andceiling eects forQUALIDEM subscales andtotal
score
Regarding the QUALIDEM subscales, we found floor or
ceiling effects for six (out of nine) subscales for patients
with mild to severe dementia, and three (out of six) sub-
scales for patients with very severe dementia. No ceil-
ing or floor effects were found for the QUALIDEM total
scores in both groups. Although ceiling and floor effects
can be a critical issue for outcomes such as QoL, we con-
sider them being less of a concern for the QUALIDEM.
To a certain extent, the small number of items per sub-
scale, which affects a scale’s discrimination, can explain
the rather high proportions of floor or ceiling effects.
However, it remains unclear whether the effects we found
were only statistically or also clinically significant. is
suggests using the QUALIDEM total score or getting a
differentiated picture by looking at all subscales and not
at isolated subscales only.
Known‑group validity
e known-group validity is a construct validity that
can be used to test whether a scale is able differentiate
between distinct groups where differences were to be
expected a priori. We derived five hypotheses based on
former research about predictors of QoL for PwD [25,
26]. For patients with mild to severe dementia, we found
evidence for all hypotheses we put forward. Only one
hypothesis was rejected for the group of patients with
very severe dementia. Where we expected no differences
between distinct groups, effect sizes were also very small.
We found medium to large effect sizes for those dis-
tinct groups where differences in the QUALIDEM score
were expected. Only the distinction between PwD with
lower versus higher number of comorbidities showed
small effect sizes. is suggests that the QUALIDEM
instrument was able to detect valid differences between
patients with different characteristics.
Scalability
e subscales “care relationship” and “social relations”
have moderate scalability, but still scoring good or
slightly better than the same subscales in the previous
studies [45, 46]. e 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
Table 6 Known-group validity for the QUALIDEM score for five distinct groups, by patients with mild to severe dementia (n = 344) and
patients with very severe dementia (n = 182)
* p values for t-test, indicating statistically signicant dierences of QUALIDEM scores between distinct groups
a TWO-sided t-test
b ONE-sided t-test
Hypothesis Mild to severe dementia
Cohen’s d p* Decision Cohen’s d p* Decision
No significant difference in QoL between younger and older elderly patients 0.11 0.319aAccept 0.15 0.346aAccept
No significant difference in QoL between female and male patients 0.10 0.403aaccept 0.14 0.388aAccept
QoL is significantly lower for patients with higher functional limitations 0.51 < 0.001bAccept 0.90 < 0.001bAccept
QoL is significantly lower for patients with higher agitation and challenging behav-
ior 1.17 < 0.001bAccept 1.35 < 0.001bAccept
QoL is significantly lower for patients with a higher number of comorbidities 0.21 0.029bAccept 0.22 0.072bReject
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
Table 7 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)
Item Nr Subscale (Item) Qualidem David Dichter etal. [30] (Total) Arons etal. [31]
Scale‑H
(Item Hi)ρ Cronbach’s α Scale‑H
(Item Hi)ρ Cronbach’s α Scale‑H
(Item Hi)ρ
A Care relationship 0.43 0.82 0.82 0.42 0.81 0.81 0.45 0.80
4 Rejects help from nursing assistants 0.24 0.48 0.47
7 Is angry 0.51 0.49 0.51
14 Has conflicts with nursing assistants 0.51 0.52 0.56
17 Accuses others 0.33 0.32 0.41
24 Appreciates help he or she receives 0.47 0.39 0.30
31 Accepts help 0.42 0.43 0.36
33 Criticizes the daily routine 0.51 0.31 0.44
B Positive aect 0.77 0.95 0.94 0.65 0.91 0.90 0.65 0.90
1 Is cheerful 0.80 0.67 0.66
5 Radiates satisfaction 0.78 0.69 0.67
8 Is capable of enjoying things in daily life 0.73 0.62 0.64
10 Is in a good mood 0.81 0.71 0.72
21 Has a smile around the mouth 0.78 0.66 0.66
40 Mood can be influenced in positive sense 0.70 0.52 0.54
C Negative aect 0.31 0.48 0.45 0.53 0.73 0.72 0.62 0.80
6 Makes an anxious impression 0.33 0.49 0.55
11 Is sad 0.26 0.59 0.65
23 Cries 0.33 0.52 0.65
D Restless tense behavior 0.55 0.76 0.74 0.45 0.69 0.68 0.36 0.61
2 Makes restless movements 0.53 0.51 0.41
19 Is restless 0.53 0.51 0.35
22 Has tense body language 0.58 0.32 0.32
E Positive self‑image 0.17 0.35 0.34 0.42 0.67 0.67 0.64 0.83
27 Indicates he or she would like more help 0.12 0.36 0.64
35 Indicates not being able to do anything 0.17 0.50 0.62
37 Indicates feeling worthless 0.22 0.41 0.66
F Social relations 0.47 0.79 0.76 0.43 0.77 0.73 0.30 0.65
3 Has contact with other patients 0.47 0.47 0.40
12 Responds positively when approached 0.46 0.44 0.34
18 Takes care of other patients 0.67 0.42 0.24
25 Cuts himself/herself off from environment 0.45 0.33 0.15
29 Is on friendly terms with one or more patients 0.55 0.45 0.37
34 Feels at ease in the company of others 0.28 0.48 0.38
G Social Isolation 0.32 0.52 0.52 0.28 0.53 0.52 0.44 0.69
16 Is rejected by other patients 0.28 0.35 0.46
20 Openly rejects contact with others 0.36 0.29 0.45
32 Calls out 0.32 0.21 0.39
H Feeling at home 0.16 0.36 0.29 0.31 0.62 0.61 0.51 0.77
13 Indicates that he or she is bored 0.09 0.26 0.52
28 Indicates feeling locked up 0.11 0.34 0.62
36 Feels at home on the ward 0.12 0.30 0.20
39 Wants to get off the ward 0.28 0.34 0.58
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Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
by Dichter etal. [45] and Arons etal. [46]. is indicates
that a specific adaptation of the QUALIDEM for hospital
settings seems reasonable.
“Negative affect” and “social isolation” show weak scal-
ability. While the result for “social isolation” is at least
comparable to Dichter etal. [45], “negative affect” has
a remarkably lower scalability compared to the other
study. ese results are less surprising, given that limi-
tations according to either weak or inconsistent scal-
ability of these two subscales have also been recognized
by the authors of the QUALIDEM instrument [11]. One
explanation might be difficulties according to the inter-
rater reliability. Personal interviews with people using
the QUALIDEM revealed that items like “cries” or “is
Table 8 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 3276 data points from items are missing)
Bold values refer to the subscale
Item Nr. Subscale (Item) Qualidem David Dichter etal. [30] (Total) Arons etal. [31]
(2017)
Scale‑H
(Item Hi)ρ Cronbach’s α Scale‑H
(Item Hi)ρ Cronbach’s α Scale‑H
(Item Hi)ρ
A Care relationship 0.50 0.74 0.70 0.47 0.73 0.67 0.43 0.79
7 Is angry 0.55 0.54 0.53
14 Has conflicts with nursing assistants 0.58 0.54 0.56
31 Accepts help 0.36 0.35 0.41
B Positive aect 0.71 0.91 0.90 0.65 0.86 0.85 0.65 0.90
5 Radiates satisfaction 0.72 0.70 0.66
8 Is capable of enjoying things in daily life 0.71 0.64 0.64
21 Has a smile around the mouth 0.75 0.65 0.68
40 Mood can be influenced in positive sense 0.67 0.59 0.61
C Negative aect 0.65 0.69 0.62 0.36 0.50 0.47 0.61 0.77
6 Makes an anxious impression 0.64 0.36 0.51
23 Cries 0.64 0.36 0.65
D Restless tense behavior 0.65 0.83 0.80 0.37 0.59 0.62 0.38 0.63
2 Makes restless movements 0.60 0.47 0.48
19 Is restless 0.61 0.45 0.43
22 Has tense body language 0.72 0.18 0.24
F Social relations 0.34 0.55 0.53 0.33 0.53 0.52 0.34 0.60
3 Has contact with other patients 0.27 0.36 0.38
12 Responds positively when approached 0.42 0.34 0.43
25 Cuts himself/herself off from environment 0.32 0.30 0.21
G Social isolation 0.45 0.65 0.66 0.20 0.42 0.41 0.41 0.66
16 Is rejected by other patients 0.39 0.25 0.46
20 Openly rejects contact with others 0.56 0.21 0.39
32 Calls out 0.42 0.13 0.37
Table 7 (continued)
Item numbers in tables correspond to those in Dichter etal. and Arons etal. to make comparison easier
Bold values refer to the subscale
Item Nr Subscale (Item) Qualidem David Dichter etal. [30] (Total) Arons etal. [31]
Scale‑H
(Item Hi)ρ Cronbach’s α Scale‑H
(Item Hi)ρ Cronbach’s α Scale‑H
(Item Hi)ρ
I Having something to do 0.56 0.69 0.64 0.18 0.23 0.24 0.39 0.53
26 Finds things to do without help from others 0.56 0.18 0.39
38 Enjoys helping with chores on the ward 0.56 0.18 0.39
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Page 13 of 15
Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
sad” are interpreted in very different ways, which seems
to make those items prone to subjectively biased percep-
tions of patients’ moods.
e subscales “positive self-image” and “feeling at
home” were not scalable. We assume that both the hos-
pital setting as well as the shorter observation period—as
compared to nursing homes—might explain these results
for the items of these two subscales. 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. e distributions of responses to this
item has a rather uniform shape. is implies that there is
a notable number 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 demen-
tia, we found strong scalability for “care relationship”,
“positive affect”, “negative affect” and “restless tense
behavior”. e differences in scalability between the
group of mild to severe dementia and very severe demen-
tia can partly be explained by the reduced number 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 removed from the sub-
scale “care relationship” in the reduced QUALIDEM ver-
sion 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
e internal consistency results only partially corre-
spond with results of the reference studies by Dichter
etal. [45] and Arons etal. [46]. For patients with mild to
severe dementia, the subscales "care relationship", "posi-
tive affect", “restless, tense behavior”, “social relations”
and “having something to do” showed similar acceptable
to excellent internal consistencies. Comparatively, there
was significantly less homogeneity for the subscale “nega-
tive affect”, "positive self-image" and "feeling at home".
In accordance with both studies, an insufficient level of
internal consistency was determined for the subscale
“social isolation”, while better characteristics (rho, alpha)
were only found for “having something to do”.
e QUALIDEM subscales for people with a very
severe dementia showed similar results as in the previ-
ous studies [45, 46]. For the subscales “care relationship”,
“positive affect”, “negative affect”, “restless, tense behav-
ior” and “social isolation” a good homogeneity could be
determined—even better values in three subscales. Com-
parably, the subscale “social relations” showed a similarly
poor internal consistency. One reason for lower Cron-
bach’s alpha values could be rather small number of items
in the subscales. is is typical for Cronbach’s alpha val-
ues. ey increase as the number of items increases [48].
Our main finding suggests that for most of the sub-
scales, especially for the group of people with very severe
dementia, the results of the internal consistency analysis
as well as the MSA were at least as good as in the two ref-
erence 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.
is result raises the question of QUALIDEM’s sensitiv-
ity 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 QUALI-
DEM’s sensitivity for change is required.
Strength andlimitations
e article is based on the first study using data from
inpatient care to analyze psychometrics of the dementia-
specific QUALIDEM instrument in Germany. ere are,
however, a number of limitations. Compared to other
studies using the QUALIDEM, we had a slightly higher
proportion of missing values in some items, but tackling
this issue with imputation techniques is feasible. Missing
values in psychometric testing are not a problem per se,
but may result in biased reliability scores [49]. erefore,
we have compared results using two different imputa-
tions techniques and the per-protocol data (i.e., no impu-
tation of missing values, see Additional file 1), which
suggests that the impact of missing values in our study is
negligible. Individual results relating item difficulty 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, relia-
bility scores (ρ, Cronbach’s α) were problematic for scales
with less than 10 items. is problem was already iden-
tified by the authors of the QUALIDEM [11], which led
to the development of the revised second version of this
assessment instrument. Unfortunately, it was not pos-
sible to measure the interrater reliability in the DAVID
project. us, we could not clearly identify the causes
for the low scalability scores of some subscales. Another
limitation of the study relates to the hypothesizing. Dur-
ing preparatory work for the study, it was only possible to
fall back on preliminary empirical findings in the context
of formation of hypotheses, which were difficult to inter-
pret due to the use of different assessment instruments.
Despite these limitations, one of the first applications in
hospital context is arguably a strength of this study, pro-
viding evidence that the QUALIDEM is a useful tool to
measure QoL of PwD in hospitals.
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Page 14 of 15
Lüdeckeetal. Health and Quality of Life Outcomes (2023) 21:12
Conclusions
Despite the limitations mentioned above (most are
general difficulties in measuring QoL) the instrument’s
psychometric properties justify its use in the context of
hospital research. In comparison with a previous evalu-
ation 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 peo-
ple with mild to severe dementia. For people with very
severe dementia, our results suggest that the QUALI-
DEM instrument seems to fit even better in a hospital
context as compared to long-term care settings. How-
ever, this result should be taken with a grain of salt,
because the lower sample size and higher proportion
of missing values only allow for limited evidence of this
conclusion. Results suggest either a revision of unsat-
isfactory items or a general reduction to six or seven
subscales for all PwD. In addition, an investigation of
the inter-rater reliability of the QUALIDEM is recom-
mended because the qualification of the nurses and the
length of stay of the patients in the hospital differ from
the previous investigations of the inter-rater reliability
of QUALIDEM in the nursing home.
Supplementary Information
The online version contains supplementary material available at https:// doi.
org/ 10. 1186/ s12955- 023- 02094-1.
Additional le1: TableA1. Scalability and internal consistency from nine
QUALIDEM subscales for people with mild to severe dementia for two
different imputation methods and per-protocol data.
Acknowledgements
Not applicable.
Author contributions
DL, MND, SN and CK OK developed the research question. DL prepared,
analyzed and interpreted the data, and drafted and finalized the manuscript.
MND, SN and CK substantially contributed to interpreting the data, drafting
the manuscript, and critically revised and approved the final manuscript. All
authors contributed to the article and approved the submitted version.
Funding
Open Access funding enabled and organized by Projekt DEAL. We acknowl-
edge financial support from the Open Access Publication Fund of UKE
- Universitätsklinikum Hamburg-Eppendorf- and DFG – German Research
Foundation. This study received no external funding.
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 [50] at
https:// osf. io/ vunmf/.
Declarations
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Competing interests
The authors declare that the research was conducted in the absence of any
commercial or financial relationships that could be construed as a potential
conflict of interest.
Author details
1 Institute of Medical Sociology, University Medical Center Hamburg-Eppen-
dorf, Martinistraße 52, 20246 Hamburg, Germany. 2 Institute of Nursing Sci-
ence, University of Cologne Medical Faculty and University Hospital Cologne,
University of Cologne, Cologne, Germany.
Received: 30 March 2022 Accepted: 17 January 2023
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