Modern medical care has been advanced, in large part, by quantitative measures that provide single, easily-assessed end points for clinical trials, clinical research, or clinical care (eg, blood pressure, serum cholesterol). In rheumatoid arthritis, several types of quantitative measures are used to assess patient status, including formal joint counts; radiographic scores; laboratory tests; patient self-report questionnaire measures of physical function, pain, global status, morning stiffness, and fatigue; as well as physical measures of functional status. Each of these measures is effective to document changes of status with treatment in groups of patients; however, no single measure can serve as a "gold standard" to document changes in each individual patient. Therefore, the measures have been combined into pooled indices that can be applied to individual patients in clinical research and clinical care.