Organic or Functional Impairment

The term impairment, used to indicate a deficit of function, may be perceived by the subject as shortness of breath, at first on exertion and eventually at rest. The clinical assessment of this complaint involves (1) establishing in detail the circumstances under which it develops; (2) gathering all relevant explanatory information (this includes determining whether dysfunction, abnormality, or disease is present and, if so, its nature and extent and, where possible, its cause); and (3) determining whether the symptom can be attributed to the dysfunction, abnormality, or disease present (usually a clinical judgment). If this is so, the symptom is considered to be organic; if not, functional. When impairment of resting function tests is severe, it is reasonable to infer that disability for work will be present as a consequence. For less severe degrees of impairment, exercise testing usually, although not always, clarifies the reserve capacity and permits an assessment of whether the symptom is on an organic or functional basis. At each stage of the clinical assessment, reference values are used. The availability of better reference values can only improve the quality of the assessment.