Classifications created by the American Rheumatism Association (now the American College of Rheumatology) that define the capacity level at which a patient with rheumatic disease is capable of functioning. Class I is complete functional capacity with ability to carry on all usual duties without handicaps; class II is functional capacity adequate to conduct normal activities despite handicap or discomfort or limited mobility of one or more joints; class III is functional capacity adequate to perform only a few or none of the duties of usual occupations or of self-care; and class IV indicates a patient who is largely or wholly incapacitated and is bedridden or confined to a wheelchair, permitting little or no self-care.