From the WONCA Classification Committee and other sources.

CLASSIFICATION: an arrangement of all elements of a domain into groups according to established criteria. A classification is characterized by:

1. Naturalness - the classes correspond to the nature of the things being classified,

2. Exhaustiveness - every relevant problem will fit into one and only one class in the system,

3. Constructability - the set of classes is constructed by a demonstrably systematic procedure.

CLASSIFICATION OF DISEASES: arrangement of diseases which have common characteristics into groups. The usefulness depends on the user. Examples are: International Classification of Primary Care (ICPC) and International Classification of Diseases, Injuries and Causes of Death (ICD).

CODING SYSTEM: is a system for classifying objects and entities (such as health problems, procedures or symptoms) using a finite set of numeric or alphanumeric identifiers (codes).

COMPUTER-BASED PATIENT RECORD: (Syn. computer-based medical record) an electronic patient record that is specifically designed to support users by providing accessibility to complete and accurate data alerts, reminders, and other aids.

COOP/WONCA CHARTS: functional health assessment charts developed for use in primary care patients. The charts are designed to measure physical fitness, feelings, daily activities, social activities, change in health and overall health.

DIAGNOSTIC CATEGORIES: in general practice three diagnostic categories are used:

1. Pathological/pathophysiological diagnoses having a proven pathological/pathophysiological substrate and/or proven etiology.

2. Symptom diagnoses using a symptom or complaint as the best medical label for the episode.

3. Nosological diagnoses (syn. syndrome) using a symptom complex based on consensus among physicians, but which lacks a proven pathological or pathophysiological basis or etiology.


  1. A physiological or psychological dysfunction. Should be distinguished from illness, which is the subjective state of a person who is aware of not being well, and from sickness which is a state of social dysfunction, i.e. a role that a person assumes when ill.
  2. Can also be construed as a more narrow concept discernable from syndrome and complaint: a biological dysfunction on basis of well-known pathological or pathophysiological processes or with a well-known etiology.

Disease can be discerned from:

a. Syndrome which is a presumed biological dysfunction of which the knowledge of causative pathological or pathophysiological processes is not accepted as conclusive for seeing it as a DISEASE, according to the literature. A dysfunction or health problem is considered a DISEASE by professional consensus. If this does not exist it is a syndrome.

                    b. Complaint is not part of a DISEASE or syndrome.

DISEASE is a concept of reality and can therefore exist without a physician's judgment. DISEASE, syndrome and complaint are congruent with diagnostic categories.

DISORDER: disturbance of the normal health status. It is used in an attempt to generalize rather than use the more specific term disease.

DSM-IV: (abbrev. Diagnostic and Statistical Manual of Mental Disorders IV): a coding system for accurate classification of psychiatric disorders for both inpatient and outpatient populations. Is developed from DSM-I (1952).

ENCOUNTER: any professional interchange between a patient and one or more members of a health care team. One or more problems or diagnoses may be identified at each encounter. Analyses of encounter data should distinguish encounters from problems.

1. Direct encounter: An encounter in which there is face to face meeting of patient and professional. This can be further divided into:

1.1. Office encounter: (surgery encounter, consultation) A direct encounter in the health care provider's office or surgery.

1.2. Home encounter: (house call, home visit) A direct encounter occurring at the patient's residence (this includes home or a friend's home where a patient is visiting, hotel, room, etc.)

1.3. Hospital encounter: a direct encounter in the hospital setting. One encounter is counted for each patient visit. Hospital encounters are further subdivided:

1.4. In-patient encounter - a direct encounter with a patient admitted to the hospital.

1.5. Out-patient encounter - a direct encounter with a patient not admitted to the hospital, either in the emergency room or in the outpatient clinic.

2. Indirect encounter: an encounter in which there is no physical or face to face meeting between the patient and the health care professional. These encounters may be subdivided by the mode of communication, e.g. telephone, letter or through a third party.

EPISODE: 'an episode of care', as used in ICPC, is the period from the first presentation of a health problem or illness to a health care provider until the completion of the last encounter for that same health problem or illness. A new episode begins with the first encounter for the initial occurrence of an illness or recurrence of an illness following a disease-free interval. From the patient's point of view an episode extends from the onset of symptoms to their complete resolution.

It can be subdivided according to its course over time:

1. Acute: (short-term) an episode of care with a duration of four weeks or less.

2. Subacute: an episode of care with a duration of between four weeks and six months.

3. Chronic: (long-term) an episode lasting six months or more.

EPISODIC CARE: health care confined to the management of presenting problems.

EPISODE OF CARE: includes all encounters for the management of a specific health problem.

EVIDENCE: proof, affirmation, documentation. In the term evidence based medicine meaning documentation based on valid clinical results.

EVIDENCE BASED MEDICINE: the process of finding relevant information in the best available medical studies to address a specific clinical problem observing the rules of science and consensual knowledge.

FALSE NEGATIVE: a negative test result in a person who has a condition which the test is designed to detect. The person is thus mistakenly labeled as unaffected, when in fact he/she is affected. See also SCREENING, SENSITIVITY, SPECIFICITY.

FALSE POSITIVE: a positive test result in a person who does not have a condition which the test is designed to detect. Thus the person is mistakenly labeled as having the condition when he/she is actually unaffected. See also SCREENING, SENSITIVITY, SPECIFICITY.

HIERARCHICAL: the characteristic of entities being arranged in a graded series. The ICPC is organized on the basis of three digits, alpha numerical rubrics which are defined by chapter and components. More precisely defined elements from five digit categories can be lumped together to the three digit level, and elements from a three digit level can be split into a four or five digit level.



INFORMATICS: (See INFORMATION TECHNOLOGY) the study of information and the ways to handle it, especially by means of information technology (e.g. computers and other electronic devices).

INTERNATIONAL CLASSIFICATION OF DISEASE (ICD): an international one-axis classification designed for encoding of mortality and morbidity purposes. It was developed under the auspices of WHO and published periodically as a complete book on diagnostic entities. It is organized in 17 chapters containing more than 12,000 different categories. Each entry is given a numerical code of up to four digits. This publication is called: "Manual of the International Statistical Classification of Diseases, Injuries and Causes of Death". The Tenth Revision (ICD-10) was introduced on January 1, 1993, but is so far implemented in very few countries. It replaces ICD-9 published in 1976.

INTERNATIONAL CLASSIFICATION OF HEALTH PROBLEMS IN PRIMARY CARE (Syn. ICHPPC): the classification of diseases and conditions in primary care. First produced by the WONCA CLASSIFICATION COMMITTEE it has been revised once under the name ICHPPC-2. Is now replaced by the much more practice orientated ICPC. ICHPPC is structured in the same way as the ICD-9 classification. HANDICAPS (Syn. ICIHD) published by WHO in 1980 as a taxonomy of the consequences of injury and disease. It uses the following definitions:

1. Impairment: "Any loss or abnormality of psychological, physiological or anatomical structure or function". Impairments represent disturbances at the organ level.

2. Disability: "Any restriction or lack (resulting from an impairment) of ability to perform an activity in a manner or within the range considered normal for a human being". Disability represents disturbances at the level of the person.

3. Handicap: "A disadvantage for a given individual, resulting from an impairment or a disability, that limits or prevents the fulfillment of a role that is normal (depending on age, sex, and social and cultural factors) for that individual". It reflects the adaptation of the individual to his/her surroundings.

INTERNATIONAL CLASSIFICATION OF PRIMARY CARE (Syn. ICPC): the classification which takes best into account the way the GP/FP works. In this classification the reason for the encounter (REF) can be classified as well as the diagnostic processes, interventions, preventions, administrative procedures and the diagnosis. It has a biaxial structure and is built up in 17 chapters, each divided in 7 components. It has been extensively tested and found to be very practicable and reliable for use in general practice with less than 3% recording error. It was published by the WONCA Classification Committee in 1980 and a new version with definitions and corrections is planned.

NATURAL HISTORY OF DISEASE: the course of a disease from onset to resolution. Many diseases have well defined stages:

1. Stage of pathological onset.

2. Presymptomatic stage: from onset to the first appearance of symptoms and/or signs. SCREENING may detect the disease at this stage.

3. Clinically manifest disease, which may regress spontaneously leading to recovery, or may be subject to remissions and relapses or progress to a fatal termination.

Detection and intervention has the aim of altering the natural history of the health problem so that it has the least impact on the person's health.

NOMENCLATURE: (Syn. terminology)  classified system of technical or scientific names. Also a list of approved terms for describing and recording observations.

PROBABILITY: the probability that a test would statistically be as extreme as or more extreme than observed if the null hypothesis were true. The letter P, followed by the abbreviation n.s.(not significant) or by the symbol < (less than) and a decimal number such as 0.05, is a statement of the probability that the difference observed could have occurred by chance, if the groups are really the same.

POSITIVE PREDICTIVE VALUE: the proportion of all people who were identified by a measurement or screening test as apparently having the disease who actually have it.

PREDICTIVE VALIDITY: the accuracy with which a measurement predicts some future event such as mortality.

PREDICTIVE VALUE: in screening and diagnostic tests the probability that a person with a positive test is a true positive (i.e. has the disease) is referred to as the "predictive value of a positive test". The predictive value of a negative test is the probability that a person with a negative test does not have the disease. The predictive value of a screening test is determined by the sensitivity and specificity of the test, and by the prevalence of the condition for which the test is used. This explains why the predictive value of the same test is very different in general practice and in hospital.

PREVALENCE: the number of all events (e.g. patients with a specific health problem) in a defined population at one point in time (POINT PREVALENCE) or during a defined period of time (PERIOD PREVALENCE). Usually expressed per 1,000 or 10,000 persons. The period may be 1 year, 4 years or a lifetime.

PREVENTION: action to prevent occurrence or development of a health problem and/or its complications. Can be divided into three categories:

1. Primary prevention: Action taken to avoid or remove the cause of a health problem in an individual or a population before it arises (i.e. immunization).

2. Secondary prevention: Action taken to prevent development of a health problem from an early stage in an individual or a population, by shortening its course and duration (i.e. screening for hypertension).

3. Tertiary prevention: Action taken to reduce the effect and prevalence of a chronic health problem in an individual or a population by minimizing the functional impairment consequent to the acute or chronic health problem (i.e. prevent complications of diabetes).

4. Quaternary Prevention: Actions taken to prevent the consequences of over medicalisation in people who have symptoms without disease (Marc Jamoulle, Free University of Brussels).

PROBABILITY: the extent to which an event is likely to occur, measured by the ratio of the favourable cases to the total number of cases possible. Expressed as a measure ranging from 0 to 1.

PROBLEM ORIENTED MEDICAL RECORD; POMR: a medical record in which the patient's history, physical findings, laboratory results, etc. are organized to give a cumulative record of problems. This distinguishes it from the chronological record where encounters are organized in a time sequence. The record includes information which is subjective (S), objective (O) including significant negative information and an assessment (A) which includes a discussion and conclusion. This is followed by diagnostic and treatment plans (P). This format (SOAP) is applied to each problem the patient presents.

READ CLINICAL CLASSIFICATION; READ CODES: the nomenclature of different classifications used by the NHS in the UK for the whole health care service. OR is a structured hierarchy of medical terms (a nomenclature) designed by a clinician (Read). Used for coding medical records and storing them in a computer system. Has become a national standard in the UK.

REASON FOR ENCOUNTER: the agreed statement of the reason(s) why a person enters the health care system, representing the demand for care by that person. The terms written down and later classified by the provider, clarify the reason for encounter and consequently the patient's demand for care, without interpreting it in the form of a diagnosis. The reason for encounter should be recognized by the patient as an acceptable description of that person's demand for care.

SCREENING; SCREENING TEST: the attempt to identify an unrecognized health problem in an individual or population by means of tests and/or other methods which discriminate between those who probably have or are at risk for a given health problem and those who are not so affected. This can be split up into:

1. Mass screening: Large scale screening of whole population groups.

2. Selective screening: Screening of selected high risk groups in the population.

SCREENING LEVEL: the normal limit or cut-off point at which a screening test is regarded as positive, i.e. uncovering an unrecognized health problem.

SENSITIVITY: the extent to which a measure detects the true differences or changes in a construct being measured. The sensitivity of a diagnostic or screening test is the proportion of people who truly have a designated disorder and are so identified by the test. The test may consist of or include clinical observations. A test with high sensitivity detects a high proportion of true cases.

SNOMED: (Systematized Nomenclature Of MEDicine) is a coded medical nomenclature that allows the recording of all disease entities and all observations related to a particular disease. The coding is multi-axial (11 axes).

SOAP: acronym for Subjective, Objective, Assessment and Plan; the basis of problem-oriented medical record.

SPECIFICITY: the specificity of a diagnostic or screening test is the proportion of people who are truly free of a designated disorder and are so identified by the test. The test may consist of or include clinical observations. A test with high specificity has few false positives.

SYMPTOM: any subjective evidence of a health problem, i.e. such evidence as perceived by the patient. Cough, pain, and tiredness are symptoms. Primary symptoms are intrinsically associated with the disease or problem. Secondary symptoms usually occur as a result of the disease process.

SYNDROME; SYNDROME DIAGNOSIS, NOSOLOGICAL DIAGNOSIS: a symptom complex in which a combination of symptoms and signs occurs more frequently than would be expected on the basis of chance alone. The term is used in three different ways:

1. The symptomatic presentation of a health problem or group of health problems. For instance the hyperthyroid syndrome. This use of the term is prevalent in general practice as many health problems are met in an early phase, or cannot or need not be diagnosed by additional diagnostic procedures. See DIAGNOSIS.

2. As synonymous jargon on basis of a historical vocabulary. Example: Down's syndrome; this is in fact a well-known disease: trisomy-21.

3. As synonym for the concept behind the term nosological diagnosis. A prerequisite for considering a set of symptoms and signs as a SYNDROME is its clinical utility for understanding, diagnosis, prognosis or treatment.

TAXONOMY OF DISEASES: a systematic classification of health problems into related diagnostic groups.

TERM(S): a word or group of words which labels concepts in a defined way. The word for the concept and the TERM are often the same. TERMS are narrower than the concept behind, because of the prerequisite 'definition'. TERMS can be defined differently in different professional domains, disciplines or specialties if they serve different clinical utilities. In primary care TERMS are concerned with broader concepts, than in more specialized disciplines, because of the clinical utility. Not defined words or labels of concepts belong to jargon.

TERMINOLOGY: all terms of a professional domain are called the TERMINOLOGY of that domain.

THESAURUS: a systematical set of professionally used words, including terms and jargon, in which each word is represented with possible synonyms, and related words designate broader or narrower concepts. The aim of a THESAURUS can be twofold: It serves as a dictionary and as translation from jargon to terminology.

UMLS (Unified Medical Language System): is a long term project to enhance MeSH to translate among existing vocabularies such as MeSH, SNOMED, ICD etc. Aims at providing a uniform interface to current and future biomedical information resources. The Metathaurus, a kind of browser, contains information about biomedical concepts and terms. In addition UMLS comprises an Information Sources Map and a Semantic Network.

VOCABULARY; GLOSSARY: a set of defined terms from a discipline.

WHO: World Health Organization.

WONCA: World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians now shortened to World Organizations of General/Family Practitioners.