Evaluation of an Epidemiological Method: Rheumatoid Arthritis in Liberia.

All current studies of rheumatoid arthritis are hindered by the lack of a precise definition of the disease. Patients in an arthritis clinic are selected, so that those with mild or short-lived forms of the disease are probably rarely seen. Because of this, better definition of rheumatoid arthritis is being sought through epidemiological studies. Four approaches are available, either separately or in combination with one another. These include finding the prevalence rates of various factors in various populations: (1) History of arthritis, morning stiffness, or joint swelling (Kellgren, Lawrence, and Aitken-Swan, 1953; Rubin, Rosenbaum, and Cobb, 1956); I, (2) Polyarthritis demonstrated by physical examination; (3) Radiological evidence for rheumatoid arthritis; (4) High agglutination titres, as, for instance, with the latex-fixation test (Singer and Plotz, 1956), indicating the presence in the sera of so-called "rheumatoid factor".