Arthritis and other rheumatic conditions (AORC) comprise more than 100 diseases. What many of them have in common is that they cause pain and aching, and stiffness or swelling in or around a joint.  

Defining AORC to assess their burden in the population requires considering both what is important to measure and what data sources are available, such as population surveys and administrative data. Complicating any definition is the 100+ conditions that comprise what is generally thought of as arthritis. Furthermore, population measures need to be relatively simple and perhaps different from definitions used in clinical practice, where there is the luxury of having a medical history, physical examination, and laboratory and radiographic data. The Centers for Diseases Control and Prevention (CDC) Arthritis Program has worked with other organizations to develop case definitions, based on the best available expertise, that allow many measures of population burden to be addressed in a consistent way.1

For self-reported population surveys, doctor-diagnosed arthritis is defined as a “yes” answer to the question: “Have you EVER been told by a doctor or other health professional that you have some form of arthritis, rheumatoid arthritis, gout, lupus, or fibromyalgia?” This measure aims to capture most of the major categories of arthritis and is considered valid for surveillance purposes of estimating population prevalence.2 For data sources using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, arthritis and other rheumatic conditions (AORC) has been defined by the National Arthritis Data Workgroup using those codes, and further divided into 10 more specific subcategories defined in Arthritis and Joint Pain Codes. Both measures were designed to exclude or minimize other major categories of musculoskeletal disease such as osteoporosis and generic chronic back pain although some adults with arthritis do have chronic back pain. Doctor-diagnosed arthritis likely is better for estimating what is happening in the general population, while AORC is likely better for estimating what is happening in the health care system.

• 1. Centers for Disease Control and Prevention. Case Definition. Available at: http://www.cdc.gov/arthritis/data_statistics/case_definition.htm. Accessed December 1, 2014.
• 2. Sacks JJ, Harrold LR, Helmick CG, Gurwitz JH, Emani S, Yood RA: Validation of a surveillance case definition for arthritis. J Rheumatol 2005:32(2):340-347.