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