In medicine, comorbidity—from Latin morbus ("sickness"), co ("together"), -ity (as if - several sicknesses together)—is the presence of one or more additional conditions often co-occurring (that is, concomitant or concurrent)
with a primary condition. Comorbidity describes the effect of all other
conditions an individual patient might have other than the primary
condition of interest, and can be physiological or psychological. In the
context of mental health, comorbidity often refers to disorders that are often coexistent with each other, such as depression and anxiety disorders. The concept of multimorbidity is related to comorbidity but presents a different meaning and approach.
Definition
The term "comorbid" has three definitions:
- to indicate a medical condition existing simultaneously but independently with another condition in a patient.
- to indicate a medical condition in a patient that causes, is caused
by, or is otherwise related to another condition in the same patient.
- to indicate two or more medical conditions existing simultaneously regardless of their causal relationship.
Comorbidity can indicate either a condition existing simultaneously,
but independently with another condition or a related derivative medical
condition. The latter sense of the term causes some overlap with the concept of complications. For example, in longstanding diabetes mellitus, the extent to which coronary artery disease is an independent comorbidity versus a diabetic complication
is not easy to measure, because both diseases are quite multivariate
and there are likely aspects of both simultaneity and consequence. The
same is true of intercurrent diseases in pregnancy. In other examples, the true independence or relation is not ascertainable because syndromes and associations are often identified long before pathogenetic commonalities are confirmed (and, in some examples, before they are even hypothesized).
In psychiatric diagnoses it has been argued in part that this "'use of
imprecise language may lead to correspondingly imprecise thinking',
[and] this usage of the term 'comorbidity' should probably be avoided."
However, in many medical examples, such as comorbid diabetes mellitus
and coronary artery disease, it makes little difference which word is
used, as long as the medical complexity is duly recognized and
addressed.
Difference from multimorbidity
Comorbidity is often referred to as multimorbidity even though the two are considered distinct clinical scenarios.
Comorbidity means that one 'index' condition is the focus of
attention, and others are viewed in relation to this. In contrast,
multimorbidity describes someone having two or more long-term (chronic)
conditions without any of them holding priority over the others. This
distinction is important in how the healthcare system treats people and
helps making clear the specific settings in which the use of one or the
other term can be preferred. Multimorbidity offers a more general and person-centered concept
that allows focusing on all of the patient's symptoms and providing a
more holistic care. In other settings, for example in pharmaceutical
research, comorbidity might often be the more useful term to use.
Mental health
In psychiatry,
psychology, and mental health counseling, comorbidity refers to the
presence of more than one diagnosis occurring in an individual at the
same time. However, in psychiatric classification, comorbidity does not
necessarily imply the presence of multiple diseases, but instead can
reflect current inability to supply a single diagnosis accounting for
all symptoms. On the DSM Axis I, major depressive disorder is a very common comorbid disorder. The Axis II personality disorders are often criticized because their comorbidity rates are excessively high, approaching 60% in some cases. Critics[who?]
assert this indicates these categories of mental illness are too
imprecisely distinguished to be usefully valid for diagnostic purposes,
impacting treatment and resource allocation. Symptom overlap is a key component against DSM classification and
serves as a note towards redefining criteria in disorders that the root
cause may not be understood thoroughly. Regardless of criticisms, it
stands that, annually, up to 45% of mental health patients fit the criteria for a comorbid diagnosis. A comorbid diagnosis is associated with more severe symptomatic expression and greater chance of dismal prognosis. Certain diagnoses such as ADHD, autism, OCD, and mood disorders
have higher rates of co-occurring or being prevalent in separate
diagnoses. "Comorbidity in OCD is the rule rather than the exception"
with OCD diagnoses facing a lifetime rate of 90%. With overlapping symptoms comes overlap in treatment as well, CBT for example is common for both ADHD and OCD with pediatric onset and can be effective for both in a comorbid diagnosis.
OCD and eating disorders have a high rate of occurrence, it is
estimated that 20-60% of patients with an eating disorder have OCD. More often, comorbidity complicates and can prevent treatment efficacy on a varying scale depending on the circumstances.
The term 'comorbidity' was introduced in medicine by Feinstein
(1970) to describe cases in which a 'distinct additional clinical
entity' occurred before or during treatment for the 'index disease', the
original or primary diagnosis. Since the terms were coined, meta
studies have shown that criteria used to determine the index disease
were flawed and subjective, and moreover, trying to identify an index
disease as the cause of the others can be counterproductive to
understanding and treating interdependent conditions. In response,
'multimorbidity' was introduced to describe concurrent conditions
without relativity to or implied dependency on another disease, so that
the complex interactions to emerge naturally under analysis of the
system as a whole.
Although the term 'comorbidity' has recently become very
fashionable in psychiatry, its use to indicate the concomitance of two
or more psychiatric diagnoses is said to be incorrect because in most
cases it is unclear whether the concomitant diagnoses actually reflect
the presence of distinct clinical entities or refer to multiple
manifestations of a single clinical entity. It has been argued that
because "'the use of imprecise language may lead to correspondingly
imprecise thinking', this usage of the term 'comorbidity' should
probably be avoided".
Due to its artifactual nature, psychiatric comorbidity has been
considered as a Kuhnian anomaly leading the DSM to a scientific crisis and a comprehensive review on the matter considers comorbidity as an epistemological challenge to modern psychiatry. The Hierarchical Taxonomy of Psychopathology is a leading alternative classification system that addresses these concerns about comorbidity.
History
Widespread study of physical and mental pathology found its place in psychiatry. I. Jensen (1975), J.H. Boyd (1984), W.C. Sanderson (1990), Yuri Nuller (1993), D.L. Robins (1994), A. B. Smulevich (1997), C.R. Cloninger (2002) and other psychiatrists discovered a number of comorbid conditions in those with psychiatric disorders.
The influence of comorbidity on the clinical progression of the
primary (basic) physical disorder, effectiveness of the medicinal
therapy and immediate and long-term prognosis of the patients was
researched by physicians and scientists of various medical fields in
many countries across the globe. These scientists and physicians
included: M. H. Kaplan (1974), T. Pincus (1986), M. E. Charlson (1987), F. G. Schellevis (1993), H. C. Kraemer (1995), M. van den Akker (1996), A. Grimby (1997), S. Greenfield (1999), M. Fortin (2004) & A. Vanasse (2004), C. Hudon (2005), L. B. Lazebnik (2005), A. L. Vertkin (2008), G. E. Caughey (2008), F. I. Belyalov (2009), L. A. Luchikhin (2010) and many others.
Inception of the term
Many
centuries ago the doctors propagated the viability of a complex
approach in the diagnosis of disease and the treatment of the patient,
however, modern medicine, which boasts a wide range of diagnostic
methods and a variety of therapeutic procedures, stresses specification.
This brought up a question: How to wholly evaluate the state of a
patient who has a number of diseases simultaneously, where to start from
and which disease(s) require(s) primary and subsequent treatment? For
many years this question stood out unanswered, until 1970, when a
renowned American doctor epidemiologist and researcher, A.R. Feinstein,
who had greatly influenced the methods of clinical diagnosis and
particularly methods used in the field of clinical epidemiology, came
out with the term of "comorbidity". The appearance of comorbidity was
demonstrated by Feinstein using the example of patients physically
affected by rheumatic fever, discovering the worst state of the
patients, who simultaneously had multiple diseases. In due course of
time after its discovery, comorbidity was distinguished as a separate
scientific-research discipline in many branches of medicine.
Evolution of the term
Presently
there is no agreed-upon terminology of comorbidity. Some authors bring
forward different meanings of comorbidity and multi-morbidity, defining
the former, as the presence of a number of diseases in a patient,
connected to each other through proven pathogenetic mechanisms and the
latter, as the presence of a number of diseases in a patient, not having
any connection to each other through any of the proven to date
pathogenetic mechanisms.
Others affirm that multi-morbidity is the combination of a number of
chronic or acute diseases and clinical symptoms in a person and do not
stress the similarities or differences in their pathogenesis.
However the principle clarification of the term was given by H. C.
Kraemer and M. van den Akker, determining comorbidity as the combination
in a patient of 2 or more chronic diseases (disorders),
pathogenetically related to each other or coexisting in a single patient
independent of each disease's activity in the patient.
Synonyms
- Polymorbidity
- Multifactorial diseases
- Polypathy
- Dual diagnosis, used for mental health issues
- Pluralpathology
Epidemiology
Comorbidity
is widespread among the patients admitted at multidiscipline hospitals.
During the phase of initial medical help, the patients having multiple
diseases simultaneously are a norm rather than an exception. Prevention
and treatment of chronic diseases declared by the World Health Organization, as a priority project for the second decade of the 20th century, are meant to better the quality of the global population.
This is the reason for an overall tendency of large-scale
epidemiological researches in different medical fields, carried-out
using serious statistical data. In most of the carried-out, randomized,
clinical researches the authors study patients with single refined
pathology, making comorbidity an exclusive criterion. This is why it is
hard to relate researches, directed towards the evaluation of the
combination of ones or the other separate disorders, to works regarding
the sole research of comorbidity. The absence of a single scientific
approach to the evaluation of comorbidity leads to omissions in clinical
practice. It is hard not to notice the absence of comorbidity in the
taxonomy (systematics) of disease, presented in ICD-10.
Clinico-pathological comparisons
All
the fundamental researches of medical documentation, directed towards
the study of the spread of comorbidity and influence of its structure,
were conducted until the 1990s. The sources of information, used by the
researchers and scientists, working on the matter of comorbidity, were
case histories, hospital records of patients and other medical documentation, kept by family doctors, insurance companies and even in the archives of patients in old houses.
The listed methods of obtaining medical information are mainly
based on clinical experience and qualification of the physicians,
carrying out clinically, instrumentally and laboratorially confirmed
diagnosis. This is why despite their competence, they are highly
subjective. No analysis of the results of postmortem of deceased
patients was carried out for any of the comorbidity researches.
"It is the duty of the doctor to carry out autopsy of the patients they treat", said once professor M. Y. Mudrov.
Autopsy allows you to exactly determine the structure of comorbidity
and the direct cause of death of each patient independent of his/her
age, gender and gender specific characteristics. Statistical data of
comorbid pathology, based on these sections, are mainly devoid of
subjectivism.
Research
The
analysis of a decade long Australian research based on the study of
patients having 6 widespread chronic diseases demonstrated that nearly
half of the elderly patients with arthritis also had hypertension, 20%
had cardiac disorders and 14% had type 2 diabetes. More than 60% of
asthmatic patients complained of concurrent arthritis, 20% complained of
cardiac problems and 16% had type 2 diabetes.
In patients with chronic kidney disease (renal insufficiency) the
frequency of coronary heart disease is 22% higher and new coronary
events 3.4 times higher compared to patients without kidney function
disorders. Progression of CKD towards end stage renal disease requiring
renal replacement therapy is accompanied by increasing prevalence of
Coronary Heart Disease and sudden death from cardiac arrest.
A Canadian research conducted upon 483 obesity patients, it was
determined that spread of obesity related accompanying diseases was
higher among females than males. The researchers discovered that nearly
75% of obesity patients had accompanying diseases, which mostly included
dyslipidemia, hypertension and type 2 diabetes. Among the young obesity
patients (from 18 to 29) more than two chronic diseases were found in
22% males and 43% females.
Fibromyalgia is a condition which is comorbid with several
others, including but not limited to; depression, anxiety, headache,
irritable bowel syndrome, chronic fatigue syndrome, systemic lupus
erythematosus, rheumatoid arthritis, migraine, and panic disorder.
The number of comorbid diseases increases with age. Comorbidity
increases by 10% in ages up to 19 years, up to 80% in people of ages 80
and older.
According to data by M. Fortin, based on the analysis of 980 case
histories, taken from daily practice of a family doctor, the spread of
comorbidity is from 69% in young patients, up to 93% among middle aged
people and up to 98% patients of older age groups. At the same time the
number of chronic diseases varies from 2.8 in young patients and 6.4
among older patients.
According to Russian data, based on the study of more than three
thousand postmortem reports (n=3239) of patients of physical
pathologies, admitted at multidisciplinary hospitals for the treatment
of chronic disorders (average age 67.8 ± 11.6 years), the frequency of
comorbidity is 94.2%. Doctors mostly come across a combination of two to
three disorders, but in rare cases (up to 2.7%) a single patient
carried a combination of 6–8 diseases simultaneously.
The fourteen-year research conducted on 883 patients of
idiopathic thrombocytopenic purpura (Werlhof disease), conducted in
Great Britain, shows that the given disease is related to a wide range
of physical pathologies. In the comorbid structure of these patients,
most frequently present are malignant neoplasms, locomotorium disorders,
skin and genitourinary system disorders, as well as haemorrhagic
complications and other autoimmune diseases, the risk of whose
progression during the first five years of the primary disease exceeds
the limit of 5%.
In a research conducted on 196 larynx cancer patients, it was
determined that the survival rate of patients at various stages of
cancer differs depending upon the presence or absence of comorbidity. At
the first stage of cancer the survival rate in the presence of
comorbidity is 17% and in its absence it is 83%, in the second stage of
cancer the rate of survivability is 14% and 76%, in the third stage it
is 28% and 66% and in the fourth stage of cancer it is 0% and 50%
respectively. Overall the survivability rate of comorbid larynx cancer
patients is 59% lower than the survivability rate of patients without
comorbidity.
Except for therapists and general physicians, the problem of
comorbidity is also often faced by specialists. Regretfully they seldom
pay attention to the coexistence of a whole range of disorders in a
single patient and mostly conduct the treatment of specific to their
specialization diseases. In current practice urologists, gynecologists,
ENT specialists, eye specialists, surgeons and other specialists all too
often mention only the diseases related to "own" field of
specialization, passing on the discovery of other accompanying
pathologies "under the control" of other specialists. It has become an
unspoken rule for any specialized department to carry out consultations
of the therapist, who feels obliged to carry out symptomatic analysis of
the patient, as well as to the form the diagnostic and therapeutic
concept, taking in view the potential risks for the patient and his
long-term prognosis.
Based on the available clinical and scientific data it is
possible to conclude that comorbidity has a range of undoubted
properties, which characterize it as a heterogeneous and often
encountered event, which enhances the seriousness of the condition and
worsens the patient's prospects. The heterogeneous character of
comorbidity is due to the wide range of reasons causing it.
Causes
- Anatomic proximity of diseased organs
- Singular pathogenetic mechanism of a number of diseases
- Terminable cause-effect relation between the diseases
- One disease resulting from complications of another
- Pleiotropy
The factors responsible for the development of comorbidity can be
chronic infections, inflammations, involutional and systematic metabolic
changes, iatrogenesis, social status, ecology and genetic
susceptibility.
Types
- Trans-syndromal comorbidity: coexistence, in a single patient, of two and/or more syndromes, pathogenetically related to each other.
- Trans-nosological comorbidity: coexistence, in a single patient, of two and/or more syndromes, pathogenetically not related to each other.
The division of comorbidity as per syndromal and nosological
principles is mainly preliminary and inaccurate, however it allows us to
understand that comorbidity can be connected to a singular cause or
common mechanisms of pathogenesis of the conditions, which sometimes
explains the similarity in their clinical aspects, which makes it
difficult to differentiate between nosologies.
- Etiological comorbidity:
It is caused by concurrent damage to different organs and systems,
which is caused by a singular pathological agent (for example due to
alcoholism in patients with chronic alcohol intoxication; pathologies
associated with smoking; systematic damage due to collagenoses).
- Complicated comorbidity: It is the result of the primary disease and
often subsequent after sometime after its destabilization appears in
the shape of target lesions (for example chronic nephratony resulting from diabetic nephropathy (Kimmelstiel-Wilson disease) in patients with type 2 diabetes; development of brain infarction resulting from complications due to hypertensive crisis in patients with hypertension).
- Iatrogenic comorbidity: It appears as a result of necessitated
negative effect of the doctor on the patient, under the conditions of
pre determine danger of one or the other medical procedure (for example,
glucocorticosteroid osteoporosis in patients treated for a long time using systematic hormonal agents (preparations); drug-induced hepatitis resulting from chemotherapy against TB, prescribed due to the conversion of tubercular tests).
- Unspecified (NOS) comorbidity: This type assumes the presence of
singular pathogenetic mechanisms of development of diseases, comprising
this combination, but require a number of tests, proving the hypothesis
of the researcher or physician (for example, erectile dysfunction as an
early sign of general atherosclerosis (ASVD); occurrence of
erosive-ulcerative lesions in the mucous membrane of the upper
gastrointestinal tract in "vascular" patients).
- "Arbitrary" comorbidity: initial alogism of the combination of
diseases is not proven, but soon can be explained with clinical and
scientific point of view (for example, combination of coronary heart
disease (CHD) and choledocholithiasis; combination of acquired heart
valvular disease and psoriasis).
Structure
There
are a number of rules for the formulation of clinical diagnosis for
comorbid patients, which must be followed by a practitioner. The main
principle is to distinguish in diagnosis the primary and background
diseases, as well as their complications and accompanying pathologies.
- Primary disease: This is the nosological form, which itself or
as a result of complications calls for the foremost necessity for
treatment at the time due to threat to the patient's life and danger of
disability. Primary is the disease, which becomes the cause of seeking
medical help or the reason for the patient's death. If the patient has
several primary diseases it is important to first of all understand the
combined primary diseases (rival or concomitant).
- Rival diseases: These are the concurrent nosological forms in a
patient, interdependent in etiologies and pathogenesis, but equally
sharing the criterion of a primary disease (for example, transmural
myocardial infarction and massive thromboembolism of pulmonary artery,
caused by phlebemphraxis of lower limbs). For practicing pathologist
rival are two or more diseases, exhibited in a single patient, each of
which by itself or through its complications could cause the patient's
death.
- Polypathia: Diseases with different etiologies and pathogenesis,
each of which separately could not cause death, but, concurring during
development and reciprocally exacerbating each other, they cause the
patient's death (for example, osteoporotic fracture of the surgical neck
of the femur and hypostatic pneumonia).
- Background disease: This helps in the occurrence of or adverse
development of the primary disease increases its dangers and helps in
the development of complications. This disease as well as the primary
one requires immediate treatment (for example, type 2 diabetes).
- Complications: Nosologies having pathogenetic relation to the
primary disease, supporting the adverse progression of the disorder,
causing acute worsening of the patient's conditions (are a part of the
complicated comorbidity). In a number of cases the complications of the
primary disease and related to it etiological and pathogenetic factors,
are indicated as conjugated disease. In this case they must be
identified as the cause of comorbidity. Complications are listed in a
descending order of prognostic or disabling significance.
- Associating diseases: Nosological units not connected etiologically
and pathogenetically with the primary disease (Listed in the order of
significance).
Diagnosis
Many
tests attempt to standardize the "weight" or value of comorbid
conditions, whether they are secondary or tertiary illnesses. Each test
attempts to consolidate each individual comorbid condition into a
single, predictive variable that measures mortality or other outcomes.
Researchers have validated such tests because of their predictive value,
but no one test is as yet recognized as a standard.
Charlson Comorbidity Index (CCI)
The Charlson Comorbidity Index predicts the mortality for a patient who may have a range of comorbid conditions, such as heart disease, AIDS, or cancer
(a total of 17 conditions). Each condition is assigned a score of 1, 2,
3, or 6, depending on the risk of dying associated with each one.
Scores are summed to provide a total score to predict mortality. Many
variations of the Charlson comorbidity index have been presented,
including the Charlson/Deyo, Charlson/Romano, Charlson/Manitoba, and
Charlson/D'Hoores comorbidity indices.
For a physician, this score is helpful in deciding how
aggressively to treat a condition. For example, a patient may have
cancer with comorbid heart disease and diabetes. These comorbidities may
be so severe that the costs and risks of cancer treatment would
outweigh its short-term benefit.
Since patients often do not know how severe their conditions are,
nurses were originally supposed to review a patient's chart and
determine whether a particular condition was present in order to
calculate the index. Subsequent studies have adapted the comorbidity
index into a questionnaire for patients.
The Charlson index, especially the Charlson/Deyo, followed by the
Elixhauser have been most commonly referred by the comparative studies
of comorbidity and multimorbidity measures.
Comorbidity–Polypharmacy Score (CPS)
The comorbidity–polypharmacy score (CPS) is a simple measure that
consists of the sum of all known comorbid conditions and all associated
medications. There is no specific matching between comorbid conditions
and corresponding medications. Instead, the number of medications is
assumed to be a reflection of the "intensity" of the associated comorbid
conditions. This score has been tested and validated extensively in the
trauma population, demonstrating good correlation with mortality,
morbidity, triage, and hospital readmissions.
Of interest, increasing levels of CPS were associated with
significantly lower 90-day survival in the original study of the score
in trauma population.
Elixhauser Comorbidity Index
The Elixhauser comorbidity measure was developed using administrative
data from a statewide California inpatient database from all
non-federal inpatient community hospital stays in California (n = 1,779,167).
The Elixhauser comorbidity measure developed a list of 30 comorbidities
relying on the ICD-9-CM coding manual. The comorbidities were not
simplified as an index because each comorbidity affected outcomes
(length of hospital stay, hospital changes, and mortality) differently
among different patients groups. The comorbidities identified by the
Elixhauser comorbidity measure are significantly associated with
in-hospital mortality and include both acute and chronic conditions. van
Walraven et al. have derived and validated an Elixhauser comorbidity
index that summarizes disease burden and can discriminate for
in-hospital mortality.
In addition, a systematic review and comparative analysis shows that
among various comorbidities indices, Elixhauser index is a better
predictor of the risk especially beyond 30 days of hospitalization.
Diagnosis-related group
Patients
who are more seriously ill tend to require more hospital resources than
patients who are less seriously ill, even though they are admitted to
the hospital for the same reason. Recognizing this, the diagnosis-related group
(DRG) manually splits certain DRGs based on the presence of secondary
diagnoses for specific complications or comorbidities (CC). The same
applies to Healthcare Resource Groups (HRGs) in the UK.
Clinical example of evaluation
Patient
S., 73 years, called an ambulance because of a sudden pressing pain in
the chest. It was known from the case history that the patient had CHD
for many years. Such chest pains were experienced by her earlier as
well, but they always disappeared after a few minutes of sublingual
administration of organic nitrates. This time taking three tablets of
nitroglycerine did not kill the pain. It was also known from the case
history that the patient had twice had myocardial infarctions during the
last ten years, as well as had an Acute Cerebrovascular Event with
sinistral hemiplegia more than 15 years ago. Apart from that the patient
had hypertension, type 2 diabetes with diabetic nephropathy,
hysteromyoma, cholelithiasis, osteoporosis and varicose pedi-vein
disease. It was also learned that the patient regularly takes a number
of antihypertensive drugs, urinatives and oral antihyperglycemic
remedies, as well as statins, antiplatelet and nootropics. In the past
the patient had undergone cholecystectomy due to cholelithiasis more
than 20 years ago, as well as the extraction of a cataract of the right
eye 4 years ago. The patient was admitted to cardiac intensive care unit
at a general hospital diagnosed for acute transmural myocardial
infarction. During the check-up moderate azotemia, mild
erythronormoblastic anemia, proteinuria and lowering of left vascular
ejection fraction were also identified.
Methods of evaluation
There are currently several generally accepted methods of evaluating (measuring) comorbidity:
- Cumulative Illness Rating Scale (CIRS): Developed in 1968 by B.
S. Linn, it became a revolutionary discovery, because it gave the
practicing doctors a chance to calculate the number and severity of
chronic illnesses in the structure of the comorbid state of their
patients. The proper use of CIRS means separate cumulative evaluation of
each of the biological systems: "0" The selected system corresponds to
the absence of disorders, "1": Slight (mild) abnormalities or previously
had disorders, "2": Illness requiring the prescription of medicinal
therapy, "3": Disease, which caused disability and "4": Acute organ
insufficiency requiring emergency therapy. The CIRS system evaluates
comorbidity in cumulative score, which can be from 0 to 56. As per its
developers, the maximum score is not compatible with the patient's life.
- Cumulative Illness Rating Scale for Geriatrics (CIRS-G): This system
is similar to CIRS, but for aged patients, offered by M. D. Miller in
1991. This system takes into account the age of the patient and the
peculiarities of the old age disorders.
- The Kaplan–Feinstein Index: This index was created in 1973 based on
the study of the effect of the associated diseases on patients with type
2 diabetes during a period of 5 years. In this system of comorbidity
evaluation all the present (in a patient) diseases and their
complications, depending on the level of their damaging effect on body
organs, are classified as mild, moderate and severe. In this case the
conclusion about cumulative comorbidity is drawn on the basis of the
most decompensated biological system. This index gives cumulative, but
less detailed as compared to CIRS, assessment of the condition of each
of the biological systems: "0": Absence of disease, "1": Mild course of
the disease, "2": Moderate disease, "3": Severe disease. The
Kaplan–Feinstein Index evaluates comorbidity by cumulative score, which
can vary from 0 to 36. Apart from that the notable deficiency of this
method of evaluating comorbidity is the excessive generalization of
diseases (nosologies) and the absence of a large number of illnesses in
the scale, which, probably, should be noted in the "miscellaneous"
column, which undermines (decreases) this method's objectivity and
productivity of this method. However the indisputable advantage of the
Kaplan–Feinstein Index as compared to CIRS is in the capability of
independent analysis of malignant neoplasms and their severities. Using
this method patient S's, age 73, comorbidity can be evaluated as of
moderate severity (16 out of 36 points), however its prognostic value is
unclear, because of the absence of the interpretation of the overall
score, resulting from the accumulation of the patient's diseases.
- Charlson Index: This index is meant for the long-term prognosis of
comorbid patients and was developed by M. E. Charlson in 1987. This
index is based on a point scoring system (from 0 to 40) for the presence
of specific associated diseases and is used for prognosis of lethality.
For its calculation the points are accumulated, according to associated
diseases, as well as the addition of a single point for each 10 years
of age for patients of ages above forty years (in 50 years 1 point, 60
years 2 points etc.). The distinguishing feature and undisputed
advantage of the Charlson Index is the capability of evaluating the
patient's age and determination of the patient's mortality rate, which
in the absence of comorbidity is 12%, at 1–2 points it is 26%; at 3–4
points it is 52% and with the accumulation of more than 5 points it is
85%. Regretfully this method has some deficiencies: Evaluating
comorbidity severity of many diseases is not considered, as well as the
absence of many important for prognosis disorders. Apart from that it is
doubtful that possible prognosis for a patient with bronchial asthma
and chronic leukemia is comparable to the prognosis for the patient
ailing from myocardial infarction and cerebral infarction. In
this case comorbidity of patient S, 73 years of age according to this
method, is equivalent to mild state (9 out of 40 points).
- Modified Charlson Index: R. A. Deyo, D. C. Cherkin, and Marcia Ciol added chronic forms of ischemic cardiac disorder and the stages of chronic cardiac insufficiency to this index in 1992.
- Elixhauser Index: The Elixhauser comorbidity measure include 30
comorbidities, which are not simplified as an index. Elixhauser shows a
better predictive performance for mortality risk especially beyond 30
days of hospitalization.
- Index of Co-Existent Disease (ICED): This Index was first developed
in 1993 by S. Greenfield to evaluate comorbidity in patients with
malignant neoplasms, later it also became useful for other categories of
patients. This method helps in calculating the duration of a patient's
stay at a hospital and the risks of repeated admittance of the same at a
hospital after going through surgical procedures. For the evaluation of
comorbidity the ICED index suggests to evaluate the patient's condition
separately as per two different components: Physiological functional
characteristics. The first component comprises 19 associated disorders,
each of which is assessed on a 4-point scale, where "0" indicates the
absence of disease and "3" indicates the disease's severe form. The
second component evaluates the effect of associated diseases on the
physical condition of the patient. It assesses 11 physical functions
using a 3-point scale, where "0" means normal functionality and "2"
means the impossibility of functionality.
- Geriatric Index of Comorbidity (GIC): Developed in 2002
- Functional Comorbidity Index (FCI): Developed in 2005.
- Total Illness Burden Index (TIBI): Developed in 2007.
Analyzing the comorbid state of patient S, 73 years of age, using the
most used international comorbidity assessment scales, a doctor would
come across totally different evaluation. The uncertainty of these
results would somewhat complicate the doctors judgment about the factual
level of severity of the patient's condition and would complicate the
process of prescribing rational medicinal therapy for the identified
disorders. Such problems are faced by doctors on everyday basis, despite
all their knowledge about medical science. The main hurdle in the way
of inducting comorbidity evaluation systems in broad based
diagnostic-therapeutic process is their inconsistency and narrow focus.
Despite the variety of methods of evaluation of comorbidity, the absence
of a singular generally accepted method, devoid of the deficiencies of
the available methods of its evaluation, causes disturbance. The absence
of a unified instrument, developed on the basis of colossal
international experience, as well as the methodology of its use does not
allow comorbidity to become doctor "friendly". At the same time due to
the inconsistency in approach to the analysis of comorbid state and
absence of components of comorbidity in medical university courses, the
practitioner is unclear about its prognostic effect, which makes the
generally available systems of associated pathology evaluation
unreasoned and therefore un-needed as well.
Treatment of comorbid patient
The
effect of comorbid pathologies on clinical implications, diagnosis,
prognosis and therapy of many diseases is polyhedral and
patient-specific. The interrelation of the disease, age and drug
pathomorphism greatly affect the clinical presentation and progress of
the primary nosology, character and severity of the complications,
worsens the patient's life quality and limit or make difficult the
remedial-diagnostic process. Comorbidity affects life prognosis and
increases the chances of fatality. The presence of comorbid disorders
increases bed days, disability, hinders rehabilitation, increases the
number of complications after surgical procedures, and increases the
chances of decline in aged people.
The presence of comorbidity must be taken into account when
selecting the algorithm of diagnosis and treatment plans for any given
disease. It is important to enquire comorbid patients about the level of
functional disorders and anatomic status of all the identified
nosological forms (diseases). Whenever a new, as well as mildly notable
symptom appears, it is necessary to conduct a deep examination to
uncover its causes. It is also necessary to be remembered that
comorbidity leads to polypragmasy (polypharmacy), i.e. simultaneous
prescription of a large number of medicines, which renders impossible
the control over the effectiveness of the therapy, increases monetary
expenses and therefore reduces compliance. At the same time,
polypragmasy, especially in aged patients, renders possible the sudden
development of local and systematic, unwanted medicinal side-effects.
These side-effects are not always considered by the doctors, because
they are considered as the appearance of comorbidity and as a result
become the reason for the prescription of even more drugs, sealing-in
the vicious circle. Simultaneous treatment of multiple disorders
requires strict consideration of compatibility of drugs and detailed
adherence of rules of rational drug therapy, based on E. M. Tareev's
principles, which state: "Each non-indicated drug is contraindicated" and B. E. Votchal said: "If the drug does not have any side-effects, one must think if there is any effect at all".
A study of inpatient hospital data in the United States in 2011
showed that the presence of a major complication or comorbidity was
associated with a great risk of intensive-care unit utilization, ranging
from a negligible change for acute myocardial infarction with major
complication or comorbidity to nearly nine times more likely for a major
joint replacement with major complication or comorbidity.
_white_bg.jpg)
