Rheumatoid cachexia (RC) is common, probably underappreciated, and incompletely understood. It is important to recognize this, because these patients can often be helped.
Rheumatoid arthritis (RA) is a chronic inflammatory joint disease affecting more women than men, with a prevalence of 0.5%–1% in the United States1,2. Nearly two-thirds of patients with RA have a metabolic abnormality accompanied by wasting of muscle mass, with the presence of stable or even increased fat mass3. This is referred to as RC. This condition is seen without any evidence of malabsorption or impaired renal or liver function.
RC was first described by Sir James Paget over 100 years ago. It is derived from the Greek word meaning “bad condition”4. It is a major cause of weight loss and increased mortality and morbidity in patients with RA.
While cachexia generally reflects advanced malnutrition and wasting, we now know that this term more specifically refers to a loss of body cell mass (BCM). BCM is clinically relevant as loss of more than 40% of baseline BCM is associated with death5. With even as little as 5% loss of BCM, there are demonstrable changes in morbidity, including reduced muscle strength, altered energy metabolism, and increased susceptibility to infections6. The average loss of BCM among patients with RA is 13%–15%, about one-third of the maximum survivable loss of BCM3.
Patients with RA have a 2-fold to 5-fold higher mortality rate than the general population because of increased risk of infections2. Thus, RC should be viewed as an important contributor to increased morbidity and …
Address correspondence to Dr. R. Panush, Keck School of Medicine, University of Southern California, HMR 711, 2011 Zonal Avenue, Los Angeles, CA 90032, USA. E-mail: panush{at}usc.edu