Diagnostic methods for evaluation of activity in inflammatory rheumatic disease

Inflammation is one of the cardinal clinical signs of rheumatic disease, although the pathogenesis of inflammation may differ from one such disease to another. The role played by inflammation in the diverse irreversible changes in the structure of the musculoskeletal system is probably also quite different. Despite this proviso, one of the prime tasks of clinical rheumatology is precise measurement of inflammation, because the information so acquired makes it possible to draw conclusions about the activity of the disease and assess the effect of therapeutic measures. Measurement of inflammation consists, fundamentally, of quantifying the classic symptoms of pain, swelling, heat, redness and limitation of movement. All attempts to measure inflammation by means of a single parameter, for instance of a humoral type (acute phase proteins), or by a single method (scintiscanning with radionuclides or thermography) have failed sooner or later. The only practical approach is to measure a number of subjective and objective parameters. With all these methods, sensitivity and reproducibility are crucial to success. In rheumatoid arthritis, the major rheumatic disease, various authors have compiled indices on the basis of individual parameters: number of painful joints, number of swollen joints, grip strength, duration of morning stiffness, a number of function tests, erythrocyte sedimentation rate (or other humoral inflammation parameters), a special pain measurement (pain scale) and subjective evaluation of the rheumatic condition by the physician and the patient.