Editing Comorbidity (section)

== 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.<ref>{{cite journal |doi=10.1370/afm.1 |title=Comorbidity: Implications for the Importance of Primary Care in 'Case' Management |year=2003 |last1=Starfield |first1=B. |journal=Annals of Family Medicine |volume=1 |pages=8–14 |pmid=15043174 |last2=Lemke |first2=KW |last3=Bernhardt |first3=T |last4=Foldes |first4=SS |last5=Forrest |first5=CB |last6=Weiner |first6=JP |issue=1 |pmc=1466556}}</ref><ref>{{cite journal |doi=10.1016/S0140-6736(06)68198-1 |title=Comorbidity and guidelines: Conflicting interests |year=2006 |last1=Van Weel |first1=Chris |last2=Schellevis |first2=François G |journal=The Lancet |volume=367 |issue=9510 |pages=550–51 |pmid=16488782|s2cid=10491258 |url=https://www.nivel.nl/nl/publicaties/2318 }}</ref><ref>{{cite journal |doi=10.1001/jama.1994.03520080061045 |title=A Critical Appraisal of the Quality of Quality-of-Life Measurements |year=1994 |last1=Gill |first1=Thomas M. |journal=JAMA |volume=272 |issue=8 |pages=619–26 |pmid=7726894 |last2=Feinstein |first2=AR}}</ref><ref>{{cite journal |doi=10.2337/diacare.11.9.725 |title=Reliability and validity of a diabetes quality-of-life measure for the diabetes control and complications trial (DCCT). The DCCT Research Group |year=1988 |journal=Diabetes Care |volume=11 |issue=9 |pages=725–32 |pmid=3066604|s2cid=219229163 }}</ref><ref>{{cite journal |doi=10.1023/A:1016654621784 |year=2000 |last1=Michelson |first1=Helena |last2=Bolund |first2=Christina |last3=Brandberg |first3=Yvonne |journal=Quality of Life Research |volume=9 |issue=10 |pages=1093–104 |pmid=11401042 |title=Multiple chronic health problems are negatively associated with health related quality of life (HRQoL) irrespective of age|s2cid=23029997 }}</ref> 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]].{{citation needed|date=February 2013}}

=== 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,<ref>{{cite journal |doi=10.1001/jama.1996.03540180029029 |title=Persons with Chronic Conditions: Their Prevalence and Costs |year=1996 |last1=Hoffman |first1=Catherine |journal=JAMA |volume=276 |issue=18 |pages=1473–79 |pmid=8903258 |last2=Rice |first2=D |last3=Sung |first3=HY}}</ref><ref>{{cite journal |doi=10.1093/gerona/53A.6.M447 |title=Morbidity, Comorbidity, and Their Association with Disability Among Community-Dwelling Oldest-Old in Israel |year=1998 |last1=Fuchs |first1=Z. |last2=Blumstein |first2=T. |last3=Novikov |first3=I. |last4=Walter-Ginzburg |first4=A. |last5=Lyanders |first5=M. |last6=Gindin |first6=J. |last7=Habot |first7=B. |last8=Modan |first8=B. |journal=The Journals of Gerontology Series A: Biological Sciences and Medical Sciences |volume=53A |issue=6 |pages=M447–55 |pmid=9823749|doi-access=free }}</ref> hospital records of patients<ref>{{cite book |last1=Daveluy |first1=C. |last2=Pica |first2=L. |last3=Audet |first3=N. |title=Enquête Sociale et de Santé 1998 |edition=2nd |location=Québec |publisher=Institut de la statistique du Québec |year=2001 |url=http://www.stat.gouv.qc.ca/publications/sante/e_soc-sante98.htm |access-date=2013-02-12 |archive-url=https://web.archive.org/web/20130126023327/http://www.stat.gouv.qc.ca//publications/sante/e_soc-sante98.htm |archive-date=2013-01-26 |url-status=dead }}{{page needed|date=February 2013}}</ref> and other medical documentation, kept by family doctors, insurance companies<ref>{{cite journal |doi=10.1001/archinte.162.20.2269 |title=Prevalence, Expenditures, and Complications of Multiple Chronic Conditions in the Elderly |year=2002 |last1=Wolff |first1=J. L. |journal=Archives of Internal Medicine |volume=162 |issue=20 |pages=2269–76 |pmid=12418941 |last2=Starfield |first2=B |last3=Anderson |first3=G|doi-access=free }}</ref> and even in the archives of patients in old houses.<ref>{{cite journal |doi=10.1017/S1041610299006067 |title=Relation Between Quality of Life and Chronic Illnesses in Elderly Living in Residential Homes: A Prospective Study |year=1999 |last1=Cuijpers |first1=Pim |last2=Van Lammeren |first2=Paula |last3=Duzijn |first3=Bernadette |journal=International Psychogeriatrics |volume=11 |issue=4 |pages=445–54 |pmid=10631590|s2cid=28550953 |doi-access=free }}</ref>

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.{{citation needed|date=April 2023}}

"It is the duty of the doctor to carry out autopsy of the patients they treat", said once professor [[:ru:Мудров, Матвей Яковлевич|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.<ref>{{cite journal |doi=10.1136/jech.2009.088260 |title=Comorbid chronic diseases, discordant impact on mortality in older people: A 14-year longitudinal population study |year=2009 |last1=Caughey |first1=G. E. |last2=Ramsay |first2=E. N. |last3=Vitry |first3=A. I. |last4=Gilbert |first4=A. L. |last5=Luszcz |first5=M. A. |last6=Ryan |first6=P. |last7=Roughead |first7=E. E. |journal=Journal of Epidemiology & Community Health |volume=64 |issue=12 |pages=1036–42 |pmid=19854745 |hdl=2440/62696 |s2cid=206990104 |url=https://digital.library.adelaide.edu.au/dspace/bitstream/2440/62696/1/hdl_62696.pdf |hdl-access=free }}</ref>

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.<ref>{{cite journal |doi=10.1016/S0002-9149(00)01176-0 |title=Prevalence of coronary artery disease, complex ventricular arrhythmias, and silent myocardial ischemia and incidence of new coronary events in older persons with chronic renal insufficiency and with normal renal function |year=2000 |last1=Aronow |first1=Wilbert S |last2=Ahn |first2=Chul |last3=Mercando |first3=Anthony D |last4=Epstein |first4=Stanley |journal=The American Journal of Cardiology |volume=86 |issue=10 |pages=1142–43, A9 |pmid=11074216}}</ref>

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.<ref>{{cite journal |last1=Bruce |first1=Sharon G. |last2=Riediger |first2=Natalie D. |last3=Zacharias |first3=James M. |last4=Young |first4=T. Kue |title=Obesity and Obesity-Related Comorbidities in a Canadian First Nation Population |journal=Preventing Chronic Disease |pmid=21213616 |url=https://www.cdc.gov/pcd/issues/2011/jan/09_0212.htm |year=2010 |volume=31 |issue=1 |pages=27–32}}</ref>

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,<ref>{{cite journal |doi=10.1097/01.rhu.0000221817.46231.18 |pmid=16755239 |title=The Incidence of Fibromyalgia and Its Associated Comorbidities |year=2006 |last1=Weir |first1=Peter T. |last2=Harlan |first2=Gregory A. |last3=Nkoy |first3=Flo L. |last4=Jones |first4=Spencer S. |last5=Hegmann |first5=Kurt T. |last6=Gren |first6=Lisa H. |last7=Lyon |first7=Joseph L. |journal=Journal of Clinical Rheumatology |volume=12 |issue=3 |pages=124–28|s2cid=24272513 }}</ref> migraine, and panic disorder.<ref>{{cite journal |doi=10.1016/0002-9343(92)90265-D |title=Comorbidity of fibromyalgia with medical and psychiatric disorders |year=1992 |last1=Hudson |first1=James I. |last2=Goldenberg |first2=Don L. |last3=Pope |first3=Harrison G. |last4=Keck |first4=Paul E. |last5=Schlesinger |first5=Lynn |journal=The American Journal of Medicine |volume=92 |issue=4 |pages=363–67 |pmid=1558082}}</ref>

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.<ref>{{cite journal |doi=10.1016/S0895-4356(97)00306-5 |title=Multimorbidity in General Practice: Prevalence, Incidence, and Determinants of Co-Occurring Chronic and Recurrent Diseases |year=1998 |last1=Van Den Akker |first1=Marjan |last2=Buntinx |first2=Frank |last3=Metsemakers |first3=Job F.M. |last4=Roos |first4=Sjef |last5=Knottnerus |first5=J. André |journal=Journal of Clinical Epidemiology |volume=51 |issue=5 |pages=367–75 |pmid=9619963}}</ref> 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.<ref>{{cite journal |last1=Fortin |first1=Martin |last2=Bravo |first2=Gina |last3=Hudon |first3=Catherine |last4=Vanasse |first4=Alain |last5=Lapointe |first5=Lise |title=Prevalence of Multimorbidity Among Adults Seen in Family Practice |journal=Annals of Family Medicine |pmid=15928225 |doi=10.1370/afm.272 |year=2005 |volume=3 |issue=3 |pages=223–8 |pmc=1466875}}</ref>

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.<ref>{{cite journal|last1=Вёрткин|first1=А. Л.|last2=Скотников|first2=А. С.|script-title=ru:Роль хронического аллергического воспаления в патогенезе бронхиальной астмы и его рациональная фармакотерапия у пациентов с полипатией|trans-title=Role of chronic allergic inflammation in bronchial asthma pathogenesis and its rational pharmacological therapy for patients with polypathia|language=ru|journal=Врач скорой помощи|issue=4|pages=6–14|url=http://medizdat-press.ru/upload/iblock/fab/4-1.pdf}}{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

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%.<ref>{{cite journal |doi=10.1155/2009/963506 |title=Comorbidities of Idiopathic Thrombocytopenic Purpura: A Population-Based Study |year=2009 |last1=Feudjo-Tepie |first1=M. A. |last2=Le Roux |first2=G. |last3=Beach |first3=K. J. |last4=Bennett |first4=D. |last5=Robinson |first5=N. J. |journal=Advances in Hematology |volume=2009 |pmid=19960044 |pages=1–12 |pmc=2778146|doi-access=free }}</ref>

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.<ref>{{cite journal |pmid=9776943 |year=1998 |last1=Taylor |first1=VM |last2=Anderson |first2=GM |last3=McNeney |first3=B |last4=Diehr |first4=P|author4-link=Paula Diehr |last5=Lavis |first5=JN |last6=Deyo |first6=RA |last7=Bombardier |first7=C |last8=Malter |first8=A |last9=Axcell |first9=T |title=Hospitalizations for back and neck problems: A comparison between the Province of Ontario and Washington State |volume=33 |issue=4 Pt 1 |pages=929–45 |pmc=1070294 |journal=Health Services Research}}</ref>

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.{{citation needed|date=February 2013}}

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.<ref>{{cite journal |doi=10.1136/bmj.a2752 |title=Comorbidity and repeat admission to hospital for adverse drug reactions in older adults: Retrospective cohort study |year=2009 |last1=Zhang |first1=M. |last2=Holman |first2=C D. J |last3=Price |first3=S. D |last4=Sanfilippo |first4=F. M |last5=Preen |first5=D. B |last6=Bulsara |first6=M. K |journal=BMJ |volume=338 |pages=a2752 |pmid=19129307 |pmc=2615549}}</ref><ref>{{cite journal |doi=10.1161/01.HYP.0000172753.96583.e1 |title=Effects of Noncardiovascular Comorbidities on Antihypertensive Use in Elderly Hypertensives |year=2005 |last1=Wang |first1=P. S. |journal=Hypertension |volume=46 |issue=2 |pages=273–79 |pmid=15983239 |last2=Avorn |first2=J |last3=Brookhart |first3=MA |last4=Mogun |first4=H |last5=Schneeweiss |first5=S |last6=Fischer |first6=MA |last7=Glynn |first7=RJ|citeseerx=10.1.1.580.8951 |s2cid=13218664 }}</ref>