People often ask how to distinguish rheumatoid arthritis (which occurs in less than 1% of the population) from the more common osteoarthritis. Rheumatoid arthritis is more inflammatory, and it is a systemic disease. If arthritis is accompanied by low-grade fever, weight loss or fatigue, that points to a possible diagnosis of RA, since osteoarthritis is a localized process affecting individual joints rather than a systemic disease.