1st International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV 26–28 June 1999 - San Diego, CA, USA

DEVELOPMENT OF CASE DEFINITIONS AND CRITERION FOR RHEUMATIC DISEASES: LESSONS FOR STUDYING THE EPIDEMIOLOGY OF LIPODYSTROPHY, IN HIV

Antiviral Therapy 1999; 4(Suppl. 2):34 (abstract no. 13)

Matthew H. Liang, MD, MPH
Department of Medicine, Division of Rheumatology Immunology and Allergy, Harvard Medical School, Robert B. Brigham Multipurpose Arthritis Center and Musculoskeletal Diseases Center Brigham and Women's Hospital Boston, MA 02115

Over 100 arthritis and musculoskeletal conditions have been described including such rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus, polymyositis/dermatomyositis, scleroderma, Reiter's disease, and the spondyloarthropathies. A characteristic of many of these conditions is: the lack of definitive diagnostic tests or histopathology. For more than 2 decades, the American Rheumatism Association now the American College of Rheumatology has systematically develop classification criteria. Typically, an ad hoc committee has been convened to develop a exhaustive list of signs and symptoms and laboratory tests seen in specific syndromes such as systemic lupus erythematosus. Then these signs and symptoms are collected in a group of patients that experts believe to have the condition and in appropriate comparison groups which have included patients that might be mistaken for the primary syndrome of interest or convenience samples of other rheumatic syndromes. The sensitive and specificity of signs, symptom, and laboratory test is then estimated. The best combination to ensure sensitivity and specificity are selected for formal diagnostic criteria.

These case definitions are not meant for making diagnoses, but for making reporting of patients more standardized and explicit to subserve clinical research. Whatever their intent, criteria are often used uncritically to establish a diagnosis in practice. Also, since many cases used in the development of criteria are from referral hospitals, the resultant criteria may be bias towards more severe or classic cases thus preventing the study of early and atypical phenotypes. Case definitions for some major syndromes such as SLE and rheumatoid arthritis have been refined over the years as testing becomes more standardized and as new subsets of disease are discovered. Despite advantages and disadvantages, case definitions are a necessary tool to begin study of any clinical syndrome. They allow standardization and the assembly of patients which can then be further studied for more specific hypothesis testing. In the rheumatic diseases they have served the field and the discovery process well.

For large-scale epidemiologic studies, the requirement for expensive imaging, laboratory tests or expert physical examination can be unpractical and prohibitively expensive.

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