THE ASSESSMENT OF MEDICAL
COMORBIDITY IN THE ELDERLY
PATIENTS WITH DEMENTIA
Letiţia Dobranici*, Cătălina Tudose**
Abstract:
Medical comorbidity is common in elderly patients with dementia and may be associated with
substantial impairment, worse health decline and mortality. Medical comorbidity has also
measurable effects on the functional outcomes of dementia patients. Treatment selection bias
occurs when a patient’s treatment is determined or influenced by factors other than the
disease itself. This is why psychiatrists should increase their efforts to detect and treat this
comorbidity. In this article we aim to clarify several aspects regarding the meaning of the
term comorbidity by reviewing its definitions and its effects, and also by presenting several
comorbidity instruments. We focus on the role of Cumulative Illness Rating Scale For
Geriatrics in the assessment of comorbidity in elderly people with dementia. We conclude that
more knowledge about comorbidity and adequate instruments to measure it would lead to
improved research of dementia in clinical care.
Key words: CIRS-G , cognitive impairment, old patient
Rezumat:
Comorbiditatea medicală este frecvent întâlnită la vârstnicii cu demenţă şi se poate asocia cu
o deteriorare semnificativă, un declin mai sever al stării de sănătate şi mortalitate. De
asemenea, comorbiditatea medicală are efecte măsurabile asupra funcţionalităţii pacienţilor
cu demenţă. Erorile de alegere a tratamentului apar frecvent atunci când acesta este
determinat sau influenţat şi de alţi factori decât de boala în sine. De aceea, psihiatrii ar
trebui să-şi sporească eforturile de a depista şi trata aceste comorbidităţi. În acest articol am
dorit să clarificăm câteva aspecte legate de semnificaţia termenului de comorbiditate
revizuindu-i definiţiile şi efectele şi, de asemenea, să prezentăm câteva instrumente de
evaluare a comorbidităţii. Ne-am concentrat asupra rolului scalei Cumulative Illness Rating
Scale For Geriatrics în evaluarea comorbidităţii vârstnicilor cu demenţă. Concluzionăm că o
mai bună cunoaştere a conceptului de comorbiditate şi a unor instrumente adecvate de
măsurare a acesteia pot conduce la îmbunătăţirea cercetării demenţei în practica clinică.
Cuvinte cheie: CIRS-G, declin cognitiv, pacient vârstnic
*MD, Senior Psychiatrist at Hospital “CFR No.2”, Bucharest; Vicepresident of Romanian Alzheimer
Association; email: [email protected]
**MD, Senior Psychiatrist at Clinical Hospital of Psychiatry “Prof. Dr. Al. Obregia”, Bucharest;
President of Romanian Alzheimer Association.
DIFFICULTIES IN DEFINING AND THE CONCEPTUALIZATION OF
COMORBIDITY
Apparently easy to define if we were to consider the etymology of the word
(prefix "co" = added, with "Morbus" = disease), comorbidity generates controversy
both in meaning of the term, the effects it has over the patient and by the difficulty to
measure it. Feinstein described the term comorbidity as “any distinct additional entity
that has existed or may occur during the clinical course of a patient who has the index
disease under study.” (1) Currently, the term comorbidity has two definitions. The
first one indicates a medical condition existing simultaneously but independently with
another condition in a patient (this is the older and more "correct" definition). A
second definition indicates a medical condition in a patient that causes, is caused by,
or is otherwise related to another condition in the same patient (this is a newer,
nonstandard definition and less well-accepted) (2) In psychiatry, comorbidity refers to
the presence of more than one mental disorder occurring in an individual at the same
time.
Therefore, some authors differentiate between comorbidity and multimorbidity
(coexistence of two or more diseases in a patient without designating a primary
disease - disease index). (3)
A particular example of multimorbidity is the dual diagnosis in psychiatry,
where two distinct disorders coexist without any implicit ordering (eg, schizophrenia
or any severe mental illness and substance abuse). Supporters of the concept of
multimorbidity tend to focus on primary care, a setting where the identification of an
index disease is quite often neither obvious nor useful. (4.5)
The difficulty to define comorbidity emerges from several reasons. One of
them is the very nature of health problems involved. Differentiating the nature of
conditions is critical to the conceptualization of comorbidity, because simultaneous
occurrence of loosely defined medical entities may signal a problem with the
classification system itself. (6, 7) For example, many professionals do not consider
depression and anxiety as two separate diagnostic entities but regard them as part of
the same spectrum, meaning that if one patients has depression and anxiety, those
should not considered comorbid disorders.
Another reason for the problems emerged in the conceptualization of
comorbidity is difficulty to determine the index disease (primary disease) (9)
considering the definition of Felstein. Depending on the research, different diseases
can be considered a disease index. The conceptualization of comorbidity becomes
more problematic when considering diseases that might be viewed just as possible
complications of other diseases. (4) This is why, it is often preferred the term
multimorbidity which implies the presence of several chronic or acute diseases in the
same person without reference to a disease index. (10) The question is who
determines the comorbid disease of a patient vs. its disease index? For example, in the
case of a patient with hypertension, cancer and depression, his general practitioner
will consider all three diseases being interested in the patient’s multimorbidity, while
the psychiatrist will consider cancer and hypertension as comorbidity and the
cardiologist will look at depression and cancer as comorbities of the patient.
The complexity of defining comorbidity derives also from the different span
of time across which the co-occurrence of two or more medical conditions is assessed.
(11) What period of time should we consider when we follow a patient’s
comorbidity? Moreover, the onset of diseases is rarely synchronous and the
establishment of the correct sequence in which comorbidities appear may be
important for the prognosis and treatment. For example, patients with diabetes who
are recently diagnosed with major depression may have a different clinical
presentation than those with an old diagnosis of major depression who are
subsequently diagnosed with diabetes, yet all can be considered as patients with
diabetes and depression.
Despite all these problems, for simplicity, we will consider comorbidity as a
list of diseases/disorders relevant to the patient, which may influence his prognosis,
excluding the disease of primary interest (the index disease). (12) For example, for a
patient recently diagnosed with dementia, comorbidity includes diabetes, hypertension
and prostate adenoma that he might have associated.
COMORBIDITY INDEX AND SEVERITY INDEX
A comorbidity index reduces all the coexistent illnesses and the severity of
those illnesses to a single numeric score, allowing comparison with scores from other
patients. The score indicates the overall severity of a patient’s medical problems, and
the score may vary within a single patient, depending on the disease of interest.
Comorbidity index should not be confused with an assessment of the impact of all
illnesses on the overall health of a patient. These are performance scales or functional
assessment scales (such as the Activities of Daily Living [ADL]). (12)
A comorbidity index is a research tool usually used in retrospective or
prospective observational studies that need to stratify patients into groups with similar
risk. In clinical trials, performance indices have been traditionally used. Comorbidity
indices by design are too coarse to replace clinical judgment in the clinical decision
making for a specific patient. (12).
Another index of interest for the clinician is the severity index representing the
total score divided by the total number of categories/diseases present in the instrument
of comorbidity we use; Severity Index = (total score/total number of categories
endorsed) (13).
WHY ARE WE INTERESTED IN COMORBIDITY?
Choice of medical treatment errors may occur more frequently when it is
conditioned by other factors than the disease itself. Typical examples in this regard
are age, personal preferences, institutionalization and, not least, somatic
comorbidities. (14) Kaplan and Feinstein stated that the influence of comorbidities
and age is carefully considered in clinical practice but is generally ignored in research
studies. (15, 2)
Medical comorbidity is common for older people with or without dementia in
the primary care system. (16) Concomitant somatic diseases significantly reduce the
independence of people with dementia and complicate the outcome and treatment of
the disease. Moreover, despite their cholinergic deficit, a significant proportion of
patients with dementia are exposed to the effects of anticholinergic medications they
receive for related diseases. (16, 17) In these conditions, a correct and complete
diagnosis is important to prevent both complications, and an inadequate or incorrect
treatment. Nevertheless, we are interested in reducing the costs, increase quality of
life of patients and decrease the burden of the carer.
Multimorbidity may affect the correct diagnosis including here the time spent
in order to make a diagnosis. (18) Thus, multimorbidity affects the duration of
hospitalization and the hospital costs. It becomes difficult to find a specific treatment
that takes account of contraindications, side effects, and of drug interactions between
different substances. Multimorbidity affects not only the evolution of disease but also
the patient's functional status and his survival. (19) We summarized these issues in
Figure 1.
Figure 1. Multiple effects of multimorbidity
HOW DO WE MEASURE COMORBIDITY?
Comorbidity indices are multi-item predictive indices with three components: a
number of items, a severity scale (including criteria) and a scoring system. The
differences between various indices of comorbidity are striking. For example, the
CIRS (20) and the CCI (21) are summative indices; the KFC (22) and the ICED (23)
are ordinal, using the greatest single scores. The score ranges are very different, as are
the type of variable and typical distribution of scores. All of these are important
factors in choosing an index. To illustrate a number of differences that can guide the
clinician to choose a scale, we illustrated in the table 1. below features some of the
most important comorbidity index known. (24)
Table 1. Differences
Index
Content
validity
CIRS-G
+++
Face
validity
++++
Reliability
Feasibility
Generalizability
+++
++++
++++
KFC
++
+++
++
++
++
CCI
++++
++
++++
+++
+
ICED
+
+
+
+
+++
Abbreviations: CCI = Charlson Comorbidity Index, CIRS-G = Cumulative Illness
Rating Scale for Geriatrics, ICED = Index of Co-Existent Disease, KFC = KaplanFeinstein Classification
++++ = excellent, +++ = good, ++ = fair, + = acceptable
Adapted after Stephen F. Hall, 2006
For a more complex understanding of the comorbidity assessment we listed in
table 2 a series of comorbidity scales. Paradoxically, given the importance of the
phenomenon of comorbidity on prognosis and evolution of a disease, the number of
comorbidity instruments is not very high, and the studies of comorbidity and the
number of studies on comorbidity is relatively small. Short descriptions were added
where information could be found.
Table 2. Comorbidity Scales
Scale
Author
M. E. Charlson (25)
Charlson Comorbidity
Index (CCI)
Comorbid Conditions
Measure
Comorbidity Conditions
Checklist
Comorbidity
Questionnaire
Comorbidity Symptom
Scale (CmSS)
C. N. Klabunde, A. L
Potosky, J. M.
Legler, J. L. Warren
(26)
C. Melfi, D.
Holleman, D. Arthur,
B. Katz (27)
A. Jablonsky, D.
Lawrence (28)
Kaplan–Feinstein
Classification, KFC
H. L. Crabtree, C. S.
Gray, A. J. Hildreth,
J. E. O'Connell, J
Brown (29)
Kaplan MH,
Feinstein AR (15, 30)
Cumulative Illness Rating
Scale
M. W. Linn, B. S.
Linn
(31)
Duke University Severity
of Illness Scale (DUSOI)
G. R. Parkerson, Jr.,
W. E. Broadhead,, C.
J. Tse (32)
Functional Comorbidity
Index (FCI)
D. L. Groll (33)
Index of Co-existent
Short description
Developed in 1987. Considers 17
diagnoses with importance in the
evolution of the index disease and assess
the mortality risk in patients with cancer.
Modified after CCI, the questionnaire
has 32 items. It assesses the comorbidity
of adult patients with chronic disease,
cancer.
Scale with 23 items which measures the
symptoms and their severity in comorbid
disorders of old people
Developed in 1974 especially for
measuring the comorbidity of patients
with diabetes.
A scale with 13 items scored from 0 to 4
severity points, developed in 1968. It is a
friendly but comprehensive review of
medical problems by organ system
The scale is used to assess the severity of
the problem under management. It is
comprised of four components:
symptoms, complications, (in the past
week) prognosis (next 6 months) and
treatability. It is scored from 0 to 4
severity points.
Developed in 2005, the scale has 18
items. It is designed to predict the
physical functionality of patients who
suffered amputations or vascular surgery
It has a bidimensional structure
Disease (ICED)
Modified Charlson
Comorbidity Index
S. Greenfield, G.
Apolone, et al. (34)
B. C. Reid, A. J.
Alberg, A. C.
Klassen, R. G.
Rozier, I. Garcia, D.
M. Winn, & J. M.
Samet (35)
measuring both the severity of the
disease and the disability. It has 27 items
THE ASSESSMENT OF COMORBIDITY IN ELDERLY PATIENTS WITH
DEMENTIA
Patients with cognitive impairment, especially dementia, commonly suffer
from a range of medical comorbidities that contribute to the progression of their
cognitive and functional decline. (36) It was noticed an acceleration of cognitive or
functional decline after acute episodes of illness (e.g. respiratory or urinary infection)
or after surgery. (37) In addition, medical conditions requiring hospitalization can be a
significant factor in the progression of a preclinical Alzheimer's dementia into a frank
dementia. (38). The mechanisms involved in this process have not yet been
elucidated. At the same time the medical comorbidity can be underdiagnosed in the
patients with cognitive impairment (39). The duration of hospitalization of patients
with significant medical comorbidity is longer, regardless their admission diagnosis.
(40) This can affect the patient's cognition and influence the rate of the decline in his
health status. Finally, medical costs will be higher. Yet despite its importance, little is
known about the comorbidity in dementia; there are very few studies on the
prevalence of medical comorbidities in dementia or about its effects on cognition and
daily functionality. Furthermore, results of existing studies determined sometimes
different conclusions (e.g. Cache County Study, 2004 (41) shows that patients with
severe dementia have a greater medical comorbidity while in his study, Sibel Tekin et
al. in 2001 (42, 43) found only a minor association between functional impairment in
patients with dementia and their associated medical conditions).
This is why, it is extremely important for those involved in the study of these
issues to use an appropriate tool for the assessment of medical comorbidities for
elderly patients with dementia. The recommended tool for this purpose remains in the
opinion of the authors Cumulative Illness Rating Scale For Geriatrics: CIRS-G. In
1992, Miller and collaborators (44) modified the CIRS scale - Cumulative Illness
Rating Scale in CIRS-G to adjust the assessment of medical comorbidities in older
people. CIRS was initially developed in 1964 to estimate the disease and the survival
rate of elderly in a hospital for war veterans. It was subsequently converted into an
index for the assessment of comorbidity removing the disease of interest.
As CIRS, CIRS-G scores according to the gravity a number of diseases, organized in
14 categories of systems:
1.HEART,
2.VASCULAR,
3.HEMATOPOIETIC (blood, blood vessels and cells, marrow, spleen, lymphatics),
4.RESPIRATORY (lungs, bronchi, trachea below the larynx),
5.EYES, EARS, NOSE AND THROAT AND LARYNX,
6.UPPER GI (esophagus, stomach, duodenum),
7. LOWER GI (intestines, hernias),
8. LIVER (including biliary and pancreatic trees),
9.RENAL (kidneys only),
10.GENITOURINARY (ureters, bladder, urethra, prostate, genitals, uterus, ovaries),
11.MUSCULOSKELETAL/INTEGUMENT (muscles, bone and skin),
12.NEUROLOGICAL (brain, spinal cord and nerves)
13.ENDOCRINE/METABOLIC AND BREAST (includes diffuse infections and
poisonings),
14.PSYCHIATRIC ILLNESS
Although dementia can be considered a neurological as well as a psychiatric
condition, for simplicity it was grouped under "psychiatric conditions" as it's effect on
functioning is primarily in this domain. If the dementia stems from multi-infarct
dementia or other neurological condition with concomitant neurological signs or
symptoms, both "neurologic" and "psychiatric" categories should be endorsed at the
appropriate level for severity.
Evaluation of each item of the 14 is granted a severity score from 0 to 4 as
follows:
0 - No Problem,
1 - Current mild problem or past significant problem
2 - Moderate disability or morbidity/ requires "first line" therapy
3 - Severe/constant significant disability/ "uncontrollable" chronic problems
4 - Extremely Severe/immediate treatment required/end organ failure/severe
impairment in function
Some "arbitrary" decisions were made for categorizing certain conditions that
could overlap more than one category and thus be counted twice, e.g., dementia is
categorized in psychiatry although it overlaps with neurology, vertigo in the Ear, Nose
and Throat category although it could also be in neurology, and CNS vascular lesions
are confined to neurology although they technically overlap with "vascular." (13)
The assessment chart of patient will have a total of five main information:
1.total number of disease/diagnostic categories recorded, 2. CIRS-G total score, 3.
Severity index (total score/total number of registered diseases), 4. The number of
categories with severity level 3, 5. the number of categories with severity level 4 (13)
Summarized, the advantages of CIRS-G scale given by the fact that data can
be gathered also from the retrospective analysis of the patient’s medical records. In
addition, it required a minimum database, familiarity with MMSE, diagnoses
according to DSM III R. The scale shows the levels of severity of each diagnostic
category, thus providing a complex picture of the overall health of the patient having
an evaluation strategy that allows the reader of the result to notice at first glance if a
patient's total score reflects some serious problems or multiple problems of mild to
moderate severity, and assesses potential severe problems with 3 and 4 severity
scores. Finally, CIRS-G has a manual of guidelines explaining how to make the
classification in levels of severity and clear indications of rating for each category
(out of 14) in part.
CONCLUSIONS
Medical comorbidity remains a major subject but relatively little studied.
There are many difficulties in the conceptualization of comorbidity. Dementia is
primarily a disease of older adults and is characterized by progressive decline in
memory and other cognitive abilities. (45) Neuropsychiatric disturbances are common
(46) and most patients with dementia due to their advanced age suffer from various
concurrent somatic comorbid diseases. (47) Thus, dementia may have a substantial
impact on the quality of life and morbidity. (48) Although physical and psychiatric
comorbidities are common in younger patients, the combination of these two variables
in the elderly and especially in patients with dementia is least documented and poorly
understood. Therefore, it becomes imperative to have and apply adequate instruments
to assess comorbidity in these patients. Cumulative Illness Rating Scale-CIRS-G can
be successfully included among these instruments. It is desirable for the clinical
research groups in Romania to use this index in order to get more valuable data in the
field of dementia research.
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